CN118207957A - Steel mesh frame installation construction method - Google Patents

Abstract

A steel mesh frame installation construction method comprises the following steps of: assembling on site; step 1.1: assembling a steel net frame; step 1.2, field assembly assurance measures; 1.3, controlling and eliminating assembly errors of the net rack; step 2: the construction method comprises the following steps; 2.1, welding construction of a steel structure; 2.2, lifting construction of the steel structure; step 2.4, lifting the steel structure of the roof; step 2.5, lifting and installing the steel structure; step 2.7, the steel structure is lifted to meet the installation and construction requirements; step 2.7.1, lifting the lifting point setting; step 2.8, preparing and checking before lifting; step 2.9, grading loading test lifting; step 2.10, formally lifting; step 2.11, welding the net rack; step 2.11.1 in-situ welding profile; step 3, analyzing a calculation book and a hydraulic lifting working condition; step 3.1, analyzing a calculation model; and 3.2, combining the load and the load. The invention can reduce the high-altitude hoisting workload, improve the construction efficiency and reduce the construction cost.

Description

Steel mesh frame installation construction method

Technical Field

The invention relates to the technical field of building construction, in particular to a steel mesh frame installation construction method.

Background

The grid structure is a space bar system structure, and the stressed bars are connected by the nodes according to a certain rule. The nodes are generally designed to be hinged, the rod is mainly subjected to axial force, and the cross section of the rod is relatively small. The bars which meet in space are mutually supported, and the stressed bars are organically combined with a supporting system, so that the materials are economical. Because the structural combination is regular, a large number of rods and nodes have the same shape and size, thereby being convenient for industrialized production and convenient for construction site installation.

The grid structure is generally a high-order hyperstatic structure, can well bear concentrated load, dynamic load and asymmetric load, and has good shock resistance. The grid structure can adapt to the requirements of public buildings and factory buildings with different spans and different supporting conditions, and also can adapt to different building planes and combinations thereof. China issued "grid structure design and construction regulations" (JGJ 7-80) in 5th 1981, 9 th 1991 revised and issued "grid structure design and construction regulations" (JGJ 7-91), and 7 th 2010 combined and issued "space grid structure technical regulations" (JGJ 7-2010) on related regulations such as grid structure, reticulated shell structure and three-dimensional pipe truss structure. In addition, aiming at the grid structure bolt ball node and accessories thereof, china specially promulgates a steel grid frame bolt ball node (JG/T10-2009) and a high-strength bolt for the steel grid frame bolt ball node (GB/T16939-2016), and aiming at the grid structure welding ball node and accessories thereof, promulgates a steel grid frame welding hollow ball node (JG/T11-2009), some provinces even go out of local standards for node production and manufacturing, for example, a local standard of Jiangsu province (DB 32/952-2006) of a conical head technical specification of the steel grid frame (shell) bolt ball node. The related standards are summaries of the current grid structure engineering and scientific research achievements in China, and the development of the grid structure in China is forcefully promoted.

The prior steel mesh frame installation construction method mainly has the following difficulties: assembling and positioning the welded ball net frame: the control points are required to be placed by professional measuring staff when the ground is assembled, the positions of net rack balls are marked on the existing road surface, deformation and accumulated errors are caused by construction, and the positions are required to be adjusted in time. Welding the welding seam of the net frame: the ball arm welding seam quality requirement is high, primary welding seams are most, and the welding difficulty is high due to the fact that flat welding, vertical welding and overhead welding coexist. And (5) lifting the steel mesh frame: the steel mesh frame is lifted and is required to be carried out after all the constructions such as the assembly welding, flaw detection, temporary lifting points, reinforcement bars, paint and the like of the mesh frame are completed, inspection and acceptance projects are more, and multi-point control is required to be coordinated and consistent during lifting.

Therefore, the installation and construction method of the steel net frame is simplified, the high-altitude hoisting workload is reduced, the construction efficiency is improved, and the construction cost is reduced.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a steel mesh frame installation construction method.

The technical scheme adopted for solving the technical problems is as follows:

The steel mesh frame installation construction method comprises the following steps: step 1: assembling on site; step 1.1: assembling a steel net frame; step 1.2, field assembly assurance measures; 1.3, controlling and eliminating assembly errors of the net rack; step 2: the construction method comprises the following steps; 2.1, welding construction of a steel structure; 2.2, lifting construction of the steel structure; step 2.4, lifting the steel structure of the roof; step 2.5, lifting and installing the steel structure; step 2.7, the steel structure is lifted to meet the installation and construction requirements; step 2.7.1, lifting the lifting point setting; step 2.8, preparing and checking before lifting; step 2.9, grading loading test lifting; step 2.10, formally lifting; step 2.11, welding the net rack; step 2.11.1 in-situ welding profile; step 3, analyzing a calculation book and a hydraulic lifting working condition; step 3.1, analyzing a calculation model; and 3.2, combining the load and the load.

The invention also has the following additional technical characteristics:

the technical scheme of the invention is further specifically optimized:

step4 stress analysis

(1) From the analysis, the maximum span of the steel structure is 110000mm, the deflection of the steel structure of the engineering is controlled within 275mm, the maximum vertical deformation of the steel structure is 110mm, the maximum stress ratio of the structure is 0.9, the stress values all meet the standard requirements, and the deformation value meets the standard requirements; according to the steel structure design standard, the maximum design stress ratio under the load effect combination of the bearing capacity limit state is 1.0; (2) checking temporary measures: maximum stress ratio is 0.6, vertical deformation is 11mm maximum, horizontal deformation is 33mm maximum, and the requirement of lifting working conditions is met; in conclusion, the deformation and stress of the structure in the whole lifting process meet the standard requirements;

(2) Hoisting and sling selection

(21) A steel wire rope: the maximum weight of the hoisting member is about 0.41t, and 2 points are selected for hoisting; and checking sling: the maximum lifting weight is about 0.41t, and when the included angle of the sling is considered according to 60 degrees, the stress of the steel wire rope is 2.4 KN: [ Fg ] -allowable tension of the steel wire rope Fg-sum of steel wire breaking force of the steel wire rope; the alpha-conversion coefficient is 0.82K-the safety coefficient of the steel wire rope, and 8 is taken when the hoisting ring and the clamping ring are used for hoisting; fg=2.4×8/0.82=23.4 kN; solving to obtain Fg=23.4kN; in order to consider the field hoisting safety, according to general technical condition of steel wire rope (GB/T20118-2017), the steel wire rope with the diameter of 8mm and a fiber core is checked; 6 x 19 nominal tensile value is 1770Mpa steel wire rope; the hoisting requirement can be met; according to the data 34.8kN > 23.4kN, the hoisting requirement is met;

(22) Shackle: according to the weight of the maximum steel structural member, the bearing of the single shackle is 0.2t, and the single shackle is selected according to the safety coefficient of 2 times of bearing capacity.

Compared with the prior art, the steel mesh frame installation construction method has the advantages that:

Advantage 1: the steel structure mainly works such as assembly, welding, painting and the like on floors to hoist and assemble parts, so that the construction efficiency is high, and the construction quality is easy to ensure;

advantage 2: the construction operation of the steel structure is concentrated on the ground and the floor, so that the influence on other professional construction is small, and the parallel construction of multiple working surfaces is facilitated, so that the total project period is controlled;

Advantage 3: the auxiliary secondary structural members of the steel structure and the like can be installed or taken when the lifting unit is assembled, so that the overhead hoisting workload can be reduced to the greatest extent, and the installation and construction period can be shortened;

Advantage 4: the air steel structure is hoisted by adopting the ultra-large component hydraulic synchronous hoisting construction technology, the technology is mature, a great amount of experience similar to engineering success can be used as a reference, and the safety of the hoisting process is ensured;

Advantage 5: the overall lifting of the steel structure unit reduces the overhead working capacity to the minimum, and the absolute time of hydraulic lifting operation is short, so that the overall construction period of the overhead steel structure installation can be effectively ensured;

Advantage 6: the hydraulic lifting equipment has small facility volume and weight, strong maneuverability and convenient transportation and installation, and is suitable for the use of the engineering;

Advantage 7: the main temporary structures such as the lifting upper and lower lifting points are arranged by utilizing the structure, and the advantages of extremely small hydraulic synchronous lifting dynamic load are utilized, so that the use amount of temporary lifting facilities can be reduced to the minimum, and the construction cost control is facilitated;

advantage 8: the lifting weight, the span and the area are not limited by the expansion combination of lifting equipment;

Advantage 9: the flexible rigging is adopted for bearing, so long as reasonable bearing hanging points exist, the lifting height and the lifting amplitude are not limited;

The advantages are 10: the hydraulic lifter anchor has reverse motion self-locking property, so that the lifting process is quite safe, and the component can be reliably locked at any position in the lifting process for a long time;

Advantage 11: the hydraulic lifting system has a millimeter-level fine adjustment function, and can realize vertical and accurate positioning in the air;

advantage 12: the device has small volume, light dead weight and large bearing capacity, and is especially suitable for lifting large-tonnage components in narrow spaces or rooms.

Drawings

FIG. 1 is a schematic view of the lifting range and the partition of a roof steel structure according to the present invention;

FIG. 2 is a schematic view of the partitioning of the working surface of the rack of the present invention;

FIG. 3 is a schematic diagram of a steel structure lifting construction flow of the invention;

FIG. 4 is a schematic view of the lifting range and the partition of the steel structure of the roof according to the present invention;

FIG. 5 is a schematic diagram of an installation hydraulic lift system of the present invention;

FIG. 6 is a schematic view of a post-load post according to the present invention;

FIG. 7 is a schematic view of the completion of the lifting operation according to the present invention;

FIG. 8 is a schematic view of a lifting elevation of a roof steel structure of the present invention;

FIG. 9 is a schematic plan layout view of lifting points of a steel structure of a roof according to the present invention;

FIG. 10 is a schematic view of a roof steel structure lifting platform arrangement of the present invention;

FIG. 11 is a schematic view of a lift platform design according to the present invention;

FIG. 12 is a schematic view of the position of a temporary reinforcing rod of the present invention, taken along line 1 and line 8;

FIG. 13 is a schematic view of the position of the A-axis and N-axis temporary reinforcing rods of the present invention;

FIG. 14 is a schematic view of a temporary spreader arrangement of the present invention;

FIG. 15 is a schematic elevation view of the guide frame and guide frame in relation to the elevator of the present invention;

FIG. 16 is a schematic view of a riser mount of the present invention;

FIG. 17 is a schematic plan view of a rear patch member of the present invention;

FIG. 18 is a schematic view of an installation elevation of the rear patch member of the present invention;

FIG. 19 is a schematic view showing the connection of the steel pipe and the hollow sphere according to the present invention

FIG. 20 is a schematic view of an un-ribbed welded hollow sphere in accordance with the present invention;

FIG. 21 is a schematic view of a ribbed welded hollow sphere in accordance with the present invention.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings.

Example 1

The steel mesh frame installation construction method comprises the following steps:

Step 1: on-site assembly

The engineering roof net frame adopts a welded ball node net frame. The net rack is assembled in situ on the ground, and is installed by adopting a scheme of integral lifting after the assembling is completed. The majority of net frame assembly adopts manual assembly, and the assembly height is 0.5m to 4.5m above the ground. The method comprises the steps of firstly, setting down a string ball node and a lower chord member, then setting up the string ball node, and finally setting up the upper chord member and a web member; the large direction of net frame assembly is from middle to periphery. Part of the welding balls are provided with lower hanging points, are welded before being lifted, and then are lifted in place along with the integral net rack.

Step 1.1: steel net frame assembly

The steel net frame is assembled in different areas and sequences as shown in figure 1. The assembly flow of the steel net rack is shown in figure 2.

Step 1.1.1, setting temporary support assembly at the bottom, and fixing a lower chord ball of the net rack in a region;

Step 1.1.2, splicing the lower chords of the net rack in one area;

Step 1.1.3, fixing a chord ball on a net rack in a region;

Step 1.1.4, splicing web members of the net rack in one area;

Step 1.1.5, splicing upper chords of the net rack in one area;

Step 1.1.6, installing a lower chord member, a web member and an upper chord member of the second area net rack in sequence;

step 1.1.7, splicing upper chords between two unit net racks;

step 1.1.8, installing a third area net rack sequentially in the same way;

Step 1.1.9, assembling a fourth, fifth and sixth area net frame;

step 1.1.10, lifting the roof truss and splicing the segmented truss on site;

step 1.2 on-site assembling measures for net frame

Step 1.2.1, setting and mechanical configuration of site assembly sites

If the arrangement of the assembly sites is reasonable, the speed of the construction progress and the level of the safe civilized construction management are directly related, and in order to ensure the smooth on-site construction, the on-site assembly sites are set as follows:

A. under the condition of meeting normal construction, the construction land is saved.

B. on the premise of meeting the civilized construction requirement, the construction of temporary facilities is reduced.

C. On the premise of ensuring smooth traffic in the field and meeting the construction requirement on materials, the transportation in the field of materials is reduced to the minimum, and particularly, the secondary transportation of the materials in the field is reduced.

D. Meets the requirements of sanitation and safety technology on construction sites and fire protection standards.

E. The construction sites are arranged nearby, so that secondary transportation in the sites is reduced.

F. the construction site is required to strengthen the field capacity management, thereby achieving the purposes of neatness, cleanness, saving and safety and seeking for balanced production.

G. The field arrangement follows three-proofing, the unstable factors are eliminated, and the fireproof, waterproof and antitheft facilities are complete and reasonable in arrangement.

H. And (5) according to the existing construction total plan of the civil engineering.

I. and according to the ground assembly quantity of the steel structure and the construction period progress condition.

In order to ensure that the roof net rack is successfully installed, a plurality of working surfaces are arranged on site to carry out net rack assembly, and 2 25t automobile cranes are arranged on each working surface to carry out net rack assembly operation.

Step 1.2.2 on-site Assembly assurance measures

(1) Assembly tire design and positioning

The split bed-jig design must meet two basic requirements:

Requirement 1) the strength requirement must be met.

Requirement 2) stability requirements must be met.

As described above, the present engineering requires a large amount of ground assembly, and the overall assembly accuracy is required to be high.

(2) Assembling technical measures

1) Main measures for guaranteeing assembly quality

The method comprises the steps of 1 adopting necessary assembling moulds, checking the positions, radians, angles and the like of the moulds according to a construction drawing after the assembling moulds are arranged, and assembling components after retesting.

And 2, performing a welding process test, measuring an actual welding shrinkage coefficient, and guiding an actual welding process.

And 3, adopting advanced processing equipment to ensure the blanking precision.

And 4, accurately positioning coordinates of all nodes of the net rack by adopting a total station in group pair positioning.

And 5, measuring the maximum calculated deflection of the engineering net rack to 299mm, and calculating the deflection of the net rack under constant load to 237mm. The arch raising height of the net frame is 180mm, the arch raising height of the net frame is reflected on each supporting point, and the arch raising requirement of the net frame is finished by supporting steel pipes with different heights.

After the assembly spot welding positioning, the geometric dimension of the net rack is checked firstly, and welding can be started after the geometric dimension is checked, and the welding is strictly performed according to the welding process requirement. And after the assembly and welding are finished, checking is performed, various correction measures are adopted, and the use precision of the product is ensured.

And 7, after the net rack is assembled on the jig frame, all constraints on the net rack are released, so that the net rack is in a free state, all dimensions of the net rack are measured in the free state, and the net rack is submitted to supervision for segmented acceptance.

2) Assembly detection measure

Measure a. Establish measurement control point

Before the mould is manufactured, the level of the reference surface of the platform is measured comprehensively by using a level meter, records are made, the position of the measured reference surface is determined according to data and actual conditions, and marks are made. The measured value of the stent point is considered when determining the height of the stent point, wherein the elevation error is less than or equal to + -3.0 mm. And measuring the verticality of the mould by using a total station, wherein the verticality is less than or equal to h/1000 and not more than 5mm, and the main control point is the elevation of the positioning point.

The actual recheck is carried out on the items by using a level gauge, a total station, a level bar and a steel rule.

Measure b, correction and adjustment card, appliance

The correction mainly adopts a puller and a jack.

Measure c. Detection method

(A) Span length

Measuring tool: steel ruler

(B) Center line and displacement

Measuring tool: theodolite, level gauge, total station, and steel ruler

(C) Elevation of the object

Measuring tool: theodolite, level gauge, total station, and steel ruler

(D) Camber of arch

Measuring tool: theodolite, level gauge, total station, and steel ruler

In order to ensure that the net rack can be deflected due to the weight of the net rack after the net rack is lifted, the arch lifting value is measured and controlled according to the arch lifting height during on-site assembly, and the arch lifting value is carried out according to a deepened design drawing.

1.3 Grid Assembly error control and cancellation

1.3.1 Design calculation for controlling and eliminating the assembling errors of the net frame

(1) According to years of construction experience, a method of analyzing error samples by adopting a computer is adopted, and errors caused by the method are considered in the deepening design.

(2) And calculating the numerical value of thermal expansion and contraction according to the temperature change, and considering in the deepening design and construction process.

(3) And positioning the nodes by using a laser total station, measuring after positioning one truss, measuring after assembling one truss, measuring after installing one section, and finally measuring after the whole section is completed.

1.3.2 On-site installation control measures for controlling and eliminating assembly errors of net rack

(1) In order to reduce the accumulated error of the welded net frame in the assembling process, the lower chord of the integral net frame is assembled from the center, the vertical and horizontal shafts are assembled firstly, the size is corrected at any time, the net frame can be unfolded from the center to the periphery when no error exists, the allowable error of a diagonal (small unit) is required to be +/-3 mm, the offset of a lower chord node is 2mm, and the offset value of the vertical and horizontal directions of the integral net frame is not more than +/-2 mm.

(2) And after the whole lower chord is assembled, checking the geometric dimension, correcting by using a total station when necessary, adjusting the height difference of each point, and recording.

(3) In order to facilitate construction and improve engineering progress, the web members and the upper chords of the lower chord assembly can be placed in a corresponding mode according to the drawing, and the lower chord assembly is carried in place.

(4) After the lower chord is assembled completely, the web members and the upper chord are assembled on the basis of no out-of-tolerance measurement, the method starts to assemble from the center, the geometric dimension of the longitudinal axis and the transverse axis is checked at any time, and the longitudinal axis and the transverse axis are corrected and assembled around.

(5) The spot welding is suitable for three points and the pipe diameter is large for four points when the net rack is assembled, and the arc striking is not required to be performed at any place except the joint of the rod piece and the node during the spot welding.

(6) Before each lower chord node and upper chord node are welded, a level gauge and a steel tape are used for measuring height, levelness, geometric dimension and deflection, so that each lower chord node and upper chord node are qualified, and the whole is qualified.

(7) And carrying out full-scale repeated inspection again for every three to five grids of assembly so as to facilitate the timely treatment of the found problems.

(8) After the whole assembly, the whole assembly is fully checked and measured once, so that no problem is left.

In the whole net rack assembling process, special attention is paid to the pad compaction of the lower chord ball, the accuracy of the axis, the quality of the welding line, the deflection and the control of the geometric dimension. The installation and positioning of the support are one of net rack control points, and the total station must be used for accurate positioning. During the installation process, inspectors check rod numbers, damages, geometric dimensions, deflection and the like of the rod at any time.

After the net rack is installed, the net rack is inspected to be qualified, and then paint and fireproof paint can be brushed at one time, so that overhead operation is avoided.

(9) The engineering net frame is a welded net frame, and the lower part of the net frame welded ball adopts temporary measure materials to control the height of the welded ball.

For positioning of the grid ball node, because of space three-dimensional coordinate positioning, a temporary supporting circular tube (specification P300X 10) is arranged below the ball node, and temporary supporting measures are positioned and fixed at the bottom by positioning and paying-off in advance, so that the grid ball node is firmly welded and used for supporting the ball node. In the assembling process, the net frame is fixed by electric welding, and is welded after accurate measurement and alignment.

Step 2: construction method

Step 2.1 Steel Structure welding construction

In view of analysis of site construction conditions and structural arrangement, the construction technology of 'integral lifting' is adopted by the construction roof steel structure installation to utilize 'ultra-large component hydraulic synchronous lifting technology' from the aspects of safety, assembly efficiency and consumption of assembly temporary measures of structure assembly, and the like, so that the safety and assembly efficiency of structure assembly can be effectively improved.

Firstly, building an assembly jig frame on the ground with the elevation of-0.500 m below the orthographic projection of a roof steel structure (lifting points are at least 0.7m higher than a lower chord plane); 12 groups of lifting platforms (upper lifting points) are arranged on the double-limb steel lattice column top with the elevation of +17.550m, and each group of lifting platforms is provided with 1 XY-TS-75 hydraulic lifter, and the total number of the lifting platforms is 12; temporary lifting appliances, temporary rods and the like are arranged at positions of the lower chord of the roof net rack corresponding to the upper lifting points, and the upper lifting points and the lower lifting points are connected through special steel strands; and lifting the whole lifting unit to the designed elevation by utilizing the hydraulic synchronous lifting system, installing the rear rod piece and the like, and dismantling the lifting platform, the reinforcing rod and the hydraulic synchronous lifting system. The position of the rear repair rod piece is occupied because the temporary lifting rod piece is welded with the welding ball, the connecting node is reserved in advance, and when the temporary rod piece is removed, a section of the temporary rod piece is left after sealing treatment, so that the base material of the welding ball is prevented from being cut. And finishing the installation operation of the roof steel structure.

Step 2.2, lifting construction of the steel structure, as shown in fig. 3.

Step 2.3 Steel construction promotes construction advantage

The steel structure in this engineering adopts whole hydraulic pressure synchronous lifting technique to hoist and mount, has following advantage:

The advantage 1 the steel structure mainly assembles, welds and paints work and carries on the hoisting assembly of the spare part in the floor, the construction efficiency is high, the construction quality is easy to guarantee;

The advantage 2 the construction operation of the steel structure is concentrated on the ground and the floor, has little influence on other professional construction, can construct in parallel on multiple working surfaces, and is beneficial to controlling the total project period;

the advantage 3 the subsidiary secondary structural member of the steel structure, etc. can be installed or taken when the lifting unit is assembled, can reduce the overhead hoisting workload to the maximum extent, shorten the installation construction cycle;

The advantage 4 adopts the construction technology of hydraulic synchronous lifting of the ultra-large component to hoist the steel structure in the air, the technology is mature, a great amount of experience similar to the success of engineering can be used as a reference, and the safety of the hoisting process is ensured;

The advantage 5 reduces the overhead working capacity to the minimum through the integral lifting of the steel structure units, and the absolute time of hydraulic lifting operation is shorter, so that the total construction period of the installation of the overhead steel structure can be effectively ensured;

The hydraulic lifting equipment has the advantages of small facility volume, small weight, strong maneuverability, convenient transportation and installation and suitability for the engineering;

the advantage 7 is that main temporary structures such as the lifting points and the like are lifted by utilizing the structure arrangement of the main temporary structures, and the advantage that the hydraulic synchronous lifting dynamic load is extremely small can reduce the use amount of temporary lifting facilities to the minimum, thereby being beneficial to the control of construction cost;

the lifting weight, the span and the area are not limited by expanding the combination through lifting equipment;

the advantage 9 adopts the flexible rigging to bear weight, as long as there are reasonable bearing hanging points, promote the height and promote the range unrestricted;

The hydraulic lifter anchor has reverse motion self-locking property, so that the lifting process is quite safe, and components can be reliably locked at any position in the lifting process for a long time;

the advantage 11 hydraulic lifting system has a millimeter-level fine adjustment function, and can realize vertical and accurate positioning in the air;

the advantage 12 is small, the dead weight is light, the bearing capacity is big, is particularly suitable for carrying out the large-tonnage component to promote in narrow space or indoor.

Step 2.4 lifting of roof steel structure

The concrete flow of lifting the steel structure of the roof is explained as follows; as shown in fig. 4

1) Firstly, building an assembly jig frame on a ground layer with the elevation of-0.500 m below the orthographic projection of a roof steel structure;

2) And assembling the lifting part of the roof structure on the assembling jig frame to form an integral lifting unit.

3) 12 Groups of lifting platforms are arranged on the double-limb steel lattice column top with the elevation of +17.550m, and each group of lifting platforms is provided with 1 XY-TS-75 hydraulic lifter, and the total number of the lifting platforms is 12;

4) Installing hydraulic synchronous lifting system equipment on a lifting platform, wherein the hydraulic synchronous lifting system equipment comprises a hydraulic pump source system, a lifter, a sensor and the like;

5) Temporary measures such as a temporary lifting appliance for lifting a lower lifting point and a temporary rod piece are installed at the position, corresponding to the upper lifting point, of the lower chord of the lifting unit;

6) Installing a special bottom anchor and a special steel strand between the lifting upper and lower lifting points;

7) Debugging a hydraulic synchronous lifting system;

8) Checking whether all temporary measures of the steel structure lifting unit and the hydraulic synchronous lifting meet design requirements;

9) After confirming that the error is not found, starting to try to lift;

10 Step-by-step loading according to the sequence of 20%, 40%, 60%, 70%, 80%, 90%, 95% and 100% of the designed load until the lifting unit is separated from the assembly jig frame;

11 After the integral lifting unit lifts about 100mm, the lifting is suspended;

12 Fine-tuning elevation of each lifting point of the lifting unit to enable the lifting unit to be in a designed posture, and standing for 2-24 hours;

13 Checking whether the steel structure lifting unit and the hydraulic synchronous lifting temporary measure are abnormal or not again before formal lifting;

14 After confirming no abnormal condition, starting formal lifting;

15 When the whole body is lifted to about 500mm away from the designed elevation, the lifting is suspended;

16 Measuring the actual elevation of each lifting point, comparing the actual elevation with the designed elevation, and making a record as a basis for continuously lifting the elevation;

17 The lifting speed is reduced, and the fine adjustment and inching functions of a hydraulic synchronous lifting computer control system are utilized to enable all lifting hanging points to reach the design position, so that the installation requirement is met;

18 Installing a net rack edge sealing rod piece to form a complete stress system;

19 95%, 90%, 80%, 70%, 60%, 50%, 40%, and the like of the hydraulic synchronous lifting system according to the designed load,

Sequentially and gradually unloading 20% of the steel strands until the steel strands are loosened, and completely transferring the roof steel structure load to the column top support;

20 Removing the hydraulic lifting system, temporary measures and the like to finish the lifting operation of the steel structure of the roof;

step 2.5 Steel Structure lifting installation

The steel structure lifting and installing process is as follows:

step 1: assembling a grid lifting unit on the ground of-0.5 m, arranging a lifting platform by utilizing a lattice column and a frame structure, installing a temporary pipe for lifting a lower lifting point at a position corresponding to an upper lifting point of the lifting unit, and installing a hydraulic lifting system; as shown in fig. 5.

Step 2: debugging a hydraulic lifting system, carrying out test lifting after confirming no abnormal condition, starting formal lifting after test lifting is free of problems, integrally lifting the net rack to a designed installation position, and mounting a rod piece after repairing the top of a column; as shown in fig. 6.

Step 3: after the structure is integrally stressed, the hydraulic lifters are unloaded sequentially, lifting equipment and temporary measures are removed, the residual rod pieces on the tops of the columns are supplemented, and lifting operation is completed. As shown in fig. 7.

Step 2.6 elevation for lifting and installing steel structure

The lifting elevation is shown in fig. 8.

Step 2.7 Steel Structure lifting installation construction requirement

Step 2.7.1 lifting the lifting Point set

And according to the results of roof steel structure arrangement and working condition calculation, the roof steel structure lifting point arrangement is shown in fig. 9.

Roof steel construction lifting device description:

1. the safety coefficients of the steel strands in the table are all larger than 2.0, so that the safety requirements are met;

2. the longest length of the steel strand is 24m, and the maximum weight of a single lifter plus the steel strand is 0.3t;

3. The steel strand is selected to have the specification of The breaking force of the single steel strand is 360kN, and the safety coefficient of the steel strand is=360/N (counter-force standard value/number).

Lifting hanging point space coordinates (with intersection point of 1 axis and A axis as origin of coordinates)

Hanging point number	X-axis coordinate (mm)	Y-axis coordinate (mm)	Z-axis coordinate (mm)	Remarks
					D01	1150.00	16250.00	20516.00
D02	1150.00	39750.00	20516.00
					D03	1150.00	64250.00	20516.00
D04	1150.00	91750.00	20516.00
					D05	22250.00	102850.00	20516.00
D06	51750.00	102850.00	20516.00
					D07	72850.00	91750.00	20516.00
D08	72850.00	64250.00	20516.00
					D09	72850.00	39750.00	20516.00
D10	72850.00	16250.00	20516.00
					D11	22250.00	1150	20516.00
D12	51750.00	1150	20516.00

Step 2.7.2 lifting temporary measures

The hydraulic synchronous lifting equipment is used for lifting the large-span steel structure, and reasonable lifting upper and lower lifting points are required to be arranged. A hydraulic lifter is arranged on the lifting upper lifting point, namely the lifting platform. The hydraulic lifter is connected with a corresponding lower lifting point on the lifting steel structure through a special lifting steel strand.

The temporary lifting measure mainly comprises a lifting platform, a temporary lifting appliance, a guide frame, a lifter fixing plate and the like.

(1) Lifting platform arrangement

The arrangement of the lifting platform in this lifting operation is shown in fig. 10 according to the structural formula of the lifting point and the reaction force of the lifting point.

(2) Platform design

The lifting platform is supported by the lattice columns and the columns, and the temporary lifting measure mainly comprises a platform beam, an upright column, a horizontal structure and the like according to the lifting process requirements and the structural characteristics. The lifting platform is shown in fig. 11.

1) Platform 1 design

Platform 1 has 4 groups. The lifting device is suitable for lifting points D02, D03, D08 and D09, and the platform consists of a platform beam, brackets, upright posts and a horizontal structure. The temporary measure material is Q355B. See the following material cross-sections and material tables. And the welding seams among the main force transmission components adopt penetration welding seams, the welding seam grade is two, the thickness of all stiffening plates is 16mm, the welding seams among the stiffening plates and the platform beams adopt fillet welding, and the welding seam size hf=0.7t.

2) Platform 2 design

The number of platforms 2 is 8. The lifting device is suitable for lifting points D01, D04-D07 and D10-D12, and the platform consists of a platform beam, brackets, upright posts and a horizontal structure. The temporary measure material is Q355B. See the following material cross-sections and material tables. And the welding seams among the main force transmission components adopt penetration welding seams, the welding seam grade is two, the thickness of all stiffening plates is 16mm, the welding seams among the stiffening plates and the platform beams adopt fillet welding, and the welding seam size hf=0.7t.

(3) Temporary measure for lower suspension point

1) Lower suspension point reinforcement

The lower suspension point is connected to the lifting unit by means of temporary reinforcement bars, the temporary reinforcement bars being positioned as shown in fig. 12 and 13.

2) Temporary sling design

The lower suspension point reinforcement design is shown in fig. 14.

Step 2.7.3 guide frame setting

In the lifting or descending process of the hydraulic lifter, the top of the hydraulic lifter is required to be reserved with a long steel strand, and if the reserved steel strand is too many, the hydraulic lifter has great influence on the operation of the steel strand in the lifting or descending process and the locking and opening of the hydraulic lifter anchor and the upper anchor. Therefore, each hydraulic lifter is required to be provided with a guide frame in advance, so that the guide frame is convenient for guiding out excessive reserved steel strands at the top of the hydraulic lifter smoothly. The redundant steel strands can be freely led backwards and downwards along the lifting platform. The guide frame arrangement is shown in fig. 15.

Step 2.7.4 lifter fixation plate

The hydraulic lifter should be fixed by the temporary fixing plate immediately after being installed in place. Each hydraulic lifter requires 4 lifter temporary fixing plates. A. The surface B needs to be flat, so that the surface B can clamp the lifter base; the C surface is welded and fixed with the lifting platform beam at the lower part, double-sided fillet welds are adopted in welding, the C surface cannot contact with the lifter base during welding, and the height of the welds is not less than 10mm. The lifter fixing plate is shown in fig. 16.

Step 2.7.5 temporarily lifting the reinforcing rod and the replacement rod

Specification of specification	Quantity of	Length (mm)	Remarks
				P76×3.75DH89×4	8	30800.74
P76×3.75DH114×4	10	40000.00
				P76×3.75DH140×4	10	40000.00
P76×3.75DH159×6	6	24000.00
				P89×4DHP114×4	8	32800.76
P89×4DHP140×4	14	60000.04
				P89×4DHP159×6	2	8000.00
P114×4DHP140×4	2	10000.00
				P140×4	16	42621.42
P140×4DHP159×6	16	61804.47
				P159×6	6	20158.12
P114×4DHP180×10	2	8000.00
				P159×6DHP180×10	8	27202.96
P180×10	2	8714.33
				P114×4DHP194×12	2	8000.00
P194×12	8	20528.20
				P219×14	4	17428.67

Step 2.8 preparation before lifting and inspection work

Step 2.8.1 temporary Lift means installation

In total, 12 groups of temporary lifting frames are arranged on site, and the specific distribution and model are required to be installed strictly according to the design requirements of the drawing. The lifting frame is machined by a workshop, welded into a whole, integrally hoisted by using an automobile crane on site, matched with a boarding car and used for guaranteeing the safety of aloft work. And the bottom of the lifting frame and the top of the lattice column are subjected to full penetration welding, and lateral supports are arranged to resist lateral stress.

Step 2.8.2 Steel strand installation

In the engineering, the steel strand penetrating method is adopted from bottom to top, namely the steel strand penetrates from the bottom to the top of the hydraulic lifter. The bottom of each bundle of steel stranded wires is leveled, and the upper ends of the penetrated steel stranded wires are fixed through the clamping heads and the anchor sheets.

After the hydraulic lifter steel strand is installed, the lower end of the steel strand bundle is penetrated into a corresponding bottom anchor structure of a lower hanging point right below, and the steel strand bundle is locked after being adjusted. The reserved steel strand at the top of each hydraulic lifter is led along the guide frame towards a preset direction.

Step 2.8.3 Hydraulic Elevator installation

The hydraulic lifter should be fixed by the temporary fixing plate immediately after being installed in place. Each hydraulic lifter requires 4 lifter temporary fixing plates. A. The surface B needs to be flat, so that the surface B can clamp the lifter base; the C surface is welded and fixed with the lifting platform beam at the lower part, double-sided fillet welds are adopted in welding, the C surface cannot contact with the lifter base during welding, and the height of the welds is not less than 10mm.

Step 2.8.4 mounting of special bottom anchor

Each hydraulic lifter corresponds to a set of special bottom anchor structure. The bottom anchor structure is arranged in the temporary lifting appliance for lifting the lower lifting point, and each set of bottom anchor is required to be vertically and concentrically arranged corresponding to the hydraulic lifter and the hole of the lifting point structure above the bottom anchor structure.

Step 2.8.5 connection of hydraulic lines

The hydraulic pump source system is connected with an oil pipe of the hydraulic lifter:

(1) When connecting the oil pipe, the combined washer in the oil pipe joint should be taken out, and the corresponding pipe joint or the butt joint should be provided with an O-shaped ring;

(2) The oil pipe at the low position is connected first to prevent the oil in the oil pipe from flowing back out. The hydraulic pump source system and the oil pipe between the hydraulic lifters are in one-to-one correspondence and are connected one by one;

(3) And connecting the oil pipes in parallel or in series according to the scheme to ensure the correctness, and performing comprehensive review after the connection is finished.

Connection of control and power lines

(1) The connection of various sensors;

(2) The hydraulic pump source system is connected with a control signal line between the hydraulic lifter;

(3) The hydraulic pump source system is connected with the computer synchronous control system;

(4) The hydraulic pump source system is connected with a power line between the distribution box;

(5) The computer controls the connection of the system power line.

Step 2.8.6 inspection and debugging of the device

(1) Inspection work before debugging

(1) Lifting temporary measure structure state inspection;

(2) Checking equipment electricity, oil pipes and nodes;

(3) Whether the temporary fixing measure of the lifting structure is removed;

(4) The lifting process is cleared of obstacles that may have an impact.

(2) System debug

After the hydraulic system is installed, the debugging is carried out according to the following steps:

(1) Checking whether joints of all valves or oil pipes on the hydraulic pump source system are loose or not, and checking whether a pressure regulating spring of an overflow valve is in a completely released state or not.

(2) And checking whether the connection of a power line and a communication cable between the hydraulic pump source system control cabinet and the hydraulic lifter is correct.

(3) Checking whether the oil pipe connection between the hydraulic pump source system and the main oil cylinder of the hydraulic lifter is correct.

(4) The system transmits power and checks whether the rotation direction of the main shaft of the hydraulic pump is correct.

(5) Under the condition that the hydraulic pump source system is not started, corresponding buttons in the control cabinet are manually operated to check whether the actions of the electromagnetic valve and the stop valve are normal or not, and whether the stop valve number and the hydraulic lifter number are corresponding or not.

(6) The travel sensor is checked to signal the corresponding signal light in the local control box.

(7) Checking before operation: starting a hydraulic pump source system, adjusting certain pressure, and expanding a main oil cylinder of a hydraulic lifter: checking whether the oil pipe connection of the cavity A and the cavity B is correct or not; checking whether the corresponding oil cylinder can be cut off by the cut-off valve.

Step 2.9 hierarchical load test lifting

The main purpose of the test lifting is to confirm to accord with the calculation of the simulation working condition and the design condition through the observation and the monitoring of the lifting unit, the lifting temporary measure and the lifting equipment system in the test lifting process, so as to ensure the safety of the lifting process.

And after the hydraulic system equipment is detected to be error-free, starting to try to lift. And determining the cylinder extending pressure (considering pressure loss) and the cylinder contracting pressure required by the hydraulic lifter by taking the counter force value of each lifting point calculated by computer simulation as a basis.

When the test lifting is started, the cylinder extending pressure of the hydraulic lifter is gradually adjusted upwards, the cylinder extending pressure is sequentially 20%,40% and 60% of the required pressure, and under the condition that all conditions are normal, the hydraulic lifter can be continuously loaded to 70%,80%,90%,95% and 100% until all lifting units are separated from the assembly jig frame.

In the process of hierarchical loading, each step of hierarchical loading is completed, and the steps of: deformation conditions before and after loading, and stability of the main body structure, such as an upper hanging point, a lower hanging point structure, a lifting unit and the like. Under all normal conditions, the next step of hierarchical loading is continued.

When the step loading is carried out to the lifting unit and the lifting unit is about to leave the jig frame, various points can be lifted off simultaneously, the lifting speed is reduced, the situation that the points are lifted off is closely observed, single-point movement lifting is carried out when necessary, and the lifting unit is ensured to be lifted off stably.

Step 2.10 formal lifting

In order to ensure the stability and safety of the lifting structure and the lifting process of the main body structure, a synchronous lifting and unloading landing control strategy of lifting point oil pressure balance, structure posture adjustment, displacement synchronous control and staged unloading in place is adopted according to the characteristics of the structure.

Step 2.10.1 synchronous lifting Point set-up

And each hydraulic lifter is provided with a set of travel sensor for measuring the lifting displacement synchronism of each hydraulic lifter in the lifting process. The main control computer forms a closed loop system of a sensor, a computer, a pump source control valve, a lifter control valve, a hydraulic lifter and a lifting unit according to displacement detection signals of all the sensors and difference values of the displacement detection signals, and controls the synchronism of the whole lifting process.

Step 2.10.2 Structure off-ground inspection

After the lifting unit leaves the assembled jig frame by about 100mm, the lifting unit is locked by using hydraulic lifting system equipment, stays in the air for 2-24 hours for comprehensive inspection (comprising a lifting point structure, a bearing system, lifting equipment and the like), and reports the inspection result to a site general command part in a written form. And checking each item normally, and performing formal lifting.

Step 2.10.3 posture check adjustment

And detecting the ground clearance of each lifting point by using a measuring instrument, and calculating the relative height difference of each lifting point. The height of each lifting point is adjusted through hydraulic lifting system equipment, so that the lifting unit reaches the design posture.

Step 2.10.4 integral synchronous lifting

And resetting the displacement sensor by taking the height of each lifting point after adjustment as a new starting position. During the overall lifting process, the attitude is maintained until it is lifted to around the design elevation.

Fine tuning of step 2.10.5 lifting process

In the lifting process, high fine adjustment is required because of air posture adjustment, post-mounting rod member installation and the like. Before the fine tuning begins, the computer synchronization control system is switched from an automatic mode to a manual mode. And synchronously inching (ascending or descending) the hydraulic lifters at each lifting point in the whole hydraulic lifting system or inching adjustment is carried out on a single hydraulic lifter according to the requirement. The inching, namely inching, adjustment precision can reach millimeter level, and the precision requirement of structural installation can be completely met.

Step 2.10.6 lifting into position

When the lifting unit is lifted to 500mm away from the designed elevation, the lifting is suspended; fine tuning of each suspension point enables the structure to be accurately lifted to reach a design position; the hydraulic lifting system equipment pauses to work, the air posture of the lifting unit is kept, and the post-installed rod piece is installed, so that the lifting unit structure forms an integral stable stress system.

Mounting of the repair rod after step 2.10.7

The rear repair rod piece is hoisted by adopting a 25t automobile crane, enough space is reserved in advance, and collision with the installed component is avoided.

And (3) installing the rear compensation rod piece, marking the relative position of the rear compensation rod piece on the welding ball in CAD, making a quadrature bottom, assembling the ground into a triangular cone, and then integrally hoisting. In order to control the overall stress of the net rack to be uniform, the installation sequence of the rear repair rod pieces is east-west symmetrical and north-south symmetrical, and the rod piece installation of the lifting point position is carried out after the rear repair rod pieces are installed.

The rear patch member is shown in fig. 17, and the rear patch member is mounted as shown in fig. 18.

Step 2.10.8 unloading of the lifting device

And (5) finishing the installation of the roof net frame in the corresponding area, and checking and accepting the welding seams and the ball joints of the net frame rod pieces. The hydraulic synchronous lifting system sequentially and synchronously unloads in a grading manner according to the sequence of 95%, 90%, 80%, 70%, 60%, 50%, 40% and 20% of the designed load until the steel strand is loosened, and the steel structure load is completely transferred to the steel structure support; and removing the hydraulic lifting system equipment and related temporary measures to complete the integral lifting installation of the lifting unit.

In the step-by-step unloading construction process, the displacement of each lifting hanging point is monitored and measured by adopting a total station, and after the abnormal analysis reason is found to be adjusted, the next stage of unloading can be performed.

The unloading process follows the following:

(1) In the unloading construction process, the safety and deformation coordination of the structure must be ensured.

(2) During the whole unloading construction process, the safety of the lifting temporary measures must be ensured.

(3) Based on theoretical calculation, deformation control is used as a core, measurement and monitoring are used as means, and safety and stability are used as targets.

Step 2.11 Net frame welding

Step 2.11.1 in-situ welding Profile

The welding work content of the engineering site is mainly welding of the welding net frame, and the welding of the welding net frame is mainly the assembly welding of the hollow balls and the rod pieces.

Welding ball and member connection welding seam: when the wall thickness is less than 4mm, fillet welds are adopted, hf=1.5 tc, the welding strength is ensured to be equal to that of the rod piece, the grade of the welds is two-level, and the welds are made of ultrasonic waves for flaw detection materials and are subjected to specific quality proof and acceptance report; when the wall thickness of the steel pipe is more than or equal to 5mm, a short liner pipe is additionally arranged, the length is 50mm, and the wall thickness is 4mm; when the wall thickness of the steel pipe is more than or equal to 8mm, the steel pipe is reinforced by adopting partial fillet weld besides the butt weld.

Step 2.11.2 welding preparation

1. Welding equipment selection

Aiming at the engineering characteristics, a carbon dioxide welding machine, an alternating current arc welding machine and the like are put into. The main welding equipment and auxiliary equipment are described as follows:

Carbon dioxide welding machine, use: full penetration butt welding of round steel pipes and box steel; spot welding the steel beam and the steel beam Niu Tuijie;

Carbon dioxide welding gun, use: the carbon dioxide welding gun is matched with the carbon dioxide gas shielded welding machine for use, and is detachable and convenient to construct.

Carbon arc gouging gun, use: the carbon arc gouging gun is used for repairing welding seams, and the anode of the carbon rod is reversely connected.

Welding rod oven, use: a temperature-controllable welding rod oven is used for adjusting the baking temperature according to the requirement, so that the baking quality of the welding rod is ensured; the special person is on duty and the electrode lead must be registered.

Infrared thermometer, use: and detecting welding preheating temperature, interlayer temperature, post-heating temperature, heat preservation temperature and the like.

Weld detection complete equipment, use: in the process of testing, the kit is used for detection.

An alternating current arc welding machine, the application: installing and positioning welding the embedded part; temporary measures for component installation and correction are welded; other auxiliary welds.

A carbon dioxide flow meter, use: the carbon dioxide flowmeter reflects the flow of carbon dioxide and is used for controlling the strength of shielding gas at the welding seam and heating the gas at constant temperature.

Air compressor machine, use: the carbon arc planer is used in combination with the air gun to provide high-pressure air for the air gun.

The welding rod heat preservation cylinder is used: the portable welding rod heat preservation cylinder is used for heat preservation of welding rods in field welding, and can keep heat preservation after power-on.

A weld gauge, use: detecting grooves, gaps, welding heights, welding feet, arc pits and the like.

Portable ultrasonic flaw detector, use: a steel internal defect nondestructive inspection professional instrument;

Operated by a professional of the corresponding qualification certificate.

1. Selection of welding materials

The main material of the engineering steel is Q355B, and the welding mode comprises manual arc welding and carbon dioxide gas shielded welding. The welding material adopts the following matched welding materials according to the design requirement:

Q235 steel welding adopts E43XX welding rod, Q355 steel welding adopts E50XX welding rod, and when members with different strength are welded, welding rod or welding wire matched with the members with low strength is adopted.

The welding rod for manual arc welding should meet the specification of the current national standard carbon steel welding rod (GB/T5117) or low alloy steel welding rod (GB/T5118), and the selected welding rod model should be suitable for the mechanical property of main metal.

The welding wire for submerged-arc automatic welding or semi-automatic welding meets the specification of the current national standard steel wire for melt welding (GB/T14957-94), and the selected welding wire and welding flux model are suitable for the mechanical properties of main metal.

The steel wire for gas shielded welding meets the specification of the current national standard steel wire for gas shielded welding (GB/T14958-94), and the model of the selected welding wire is suitable for the mechanical properties of main metal.

Step 2.11.3 welding Process evaluation reference

(1) Parameter reference table for manual arc welding

(2) Carbon dioxide gas shielded welding (flat welding) parameter reference table

(3) Parameter reference table for carbon dioxide gas shielded welding (transverse welding and vertical welding)

Step 2.11.5 in-situ welding procedure

1. Specific requirements for field welding operation

Claim 1: welding: 1. and a welding mode of filling the middle part and covering the surface of the steel plate by manual welding and bottoming at the root part and semi-automatic welding is adopted.

2. The weldment with the lining plate is welded by adopting CO2 gas shielded semiautomatic welding.

Claim 2: the welding section keeps continuous welding, and multiple arc extinction and starting are avoided. When penetrating through the process hole at the installation connecting plate, the joint must be sent through the center of the connecting plate, and the joint parts should be staggered.

Claim 3: when one or more pauses occur in the same layer of welding seam and the welding is required to be continued, the initial welding head needs to be started at the position of at least 15mm after the original arc-extinguishing position, and the direct arc starting at the original arc-extinguishing position is forbidden. When the CO2 gas shielded welding is in arc quenching, the welding gun can be removed after the shielding gas is completely stopped from being supplied and the welding line is completely condensed. The arc is inhibited from stopping burning and the welding gun is removed, so that the red-hot molten pool is exposed to the atmosphere and loses CO2 gas protection.

Claim 4: and (3) priming: and igniting an electric arc on an arc striking plate at the position 50mm in front of the starting point of the welding line, and then carrying out welding construction by carrying out arc transportation. When the arc is extinguished, the arc is not allowed to be extinguished at the joint, but the arc is drawn to an arc extinguishing plate exceeding 50mm at the joint, an arc pit is filled, the arc is transported by adopting a reciprocating arc transporting method, the arc is slightly stopped at two sides, the included angle between welding flesh and a groove is avoided, and the gentle and excessive requirement is met.

Claim 5: and (2) filling layer: the method comprises the steps of removing the protruding part and the redundant part caused by arc striking on a first layer of welding bead before filling welding, removing splashes and dust adhered to a slope wall, and checking whether the edge of a groove is fused or not and the included angle of the recess. When CO2 gas shielded welding is carried out, the gas flow is preferably controlled at 40-55L/min, the welding wire is stretched at 20-25mm, the welding speed is controlled at 5-7mm/s, the molten pool is kept in a level state, the welding operation adopts a diagonal circle method, and when a layer is filled for welding a surface layer, the depth of 1.5-2mm is reserved, so that the bevel edge can be seen clearly when the cover surface is covered.

Claim 6: the surface layer welding directly relates to whether the appearance quality of the welding seam meets the quality inspection standard, and the whole welding seam is repaired before welding, so that the concave-convex part is eliminated, and the continuous and uniform forming of the welding seam is maintained. The surface layer weld joint should be in the last weld joint welding, take care to prevent the limit portion from appearing the undercut defect.

Claim 7: in the welding process: the interlayer temperature of the welding seam should be always controlled between 100-150 ℃, the welding process is required to have maximum continuity, the repair defect occurs in the welding process, the welding is stopped when the welding slag is cleaned, the temperature is reduced, and a heating tool is required to heat the welding seam until the welding seam reaches the specified value, and then the welding can be performed. When the welding seam is cracked, the welder must not be treated with no permission, the welding technology responsible person should be reported to find out the reason, and the welder can treat after the repair measures are determined.

Claim 8: post-weld cleaning and inspection: after welding, the spatter and welding slag should be removed, after the spatter and welding slag are removed, the appearance of the welding seam is checked by a welding seam gauge and a magnifying glass, the defects of sinking, undercut, air holes, unfused, cracks and the like cannot be caused, a post-welding self-checking record is made, the number steel seal of an operating welder is identified after the self-checking is qualified, the steel seal is identified at the position 50mm away from the longitudinal direction of the welding seam in the middle of the joint, the identification at the edge is forbidden, and the occurrence of a cracking source is prevented. The appearance quality inspection standard should conform to the I-level specification of GB-50221 Table 4-7-13.

Claim 9: nondestructive testing of welding seams: the weldment is cooled to normal temperature, and nondestructive inspection is carried out, wherein the inspection standard accords with the specification of GB/T11345 Manual ultrasonic flaw detection method and quality grading method for steel weld joints.

2. Pre-weld preparation

Preparation 1: before assembling, rust and dirt are carefully removed from the 15-20mm inner wall of the groove at the joint by using a file, abrasive cloth and a disc steel wire brush. Because the surface finish of the steel is poor, the concave part must be polished by an angle grinder before assembly, the surface of the groove has the phenomena of uneven and rusted, and the groove cleaning is the key point of the process.

Preparation 2: and (3) jacking up the groove gap at the joint by using a jack or other lifting appliance, and reserving welding shrinkage. And checking whether the splicing gap, the misalignment condition and the groove angle meet the requirements or not by using a steel ruler, a square, a wedge ruler and a welding seam gauge.

Preparation 3: the butt joint is welded by using a small-diameter phi 3.2mm E5515 welding rod, the welding rod is baked according to the specification, the welding length of the butt joint is less than or equal to 50mm every part, and the thickness of welding meat is about 4mm.

Preparation 4: and grinding the initial welding and final welding positions into a gentle slope shape by adopting an angle grinder after the positioning welding.

3. Welding construction process

(1) Welding construction process

The bottom layer process comprises the following steps: when the butt joint is welded at the root, the arc starting is carried out from the 10mm position of the central line of the lowest position of the welding port to the central line of the highest position of the component port, which is about 10mm, the bottom sealing welding of the half welding port is completed, the first half of the initial welding and the final position of the other half of the welding port are polished into a gentle slope shape by an angle grinder before the other half of the welding port is welded, and after no unfused phenomenon is confirmed, the arc starting is carried out on the welding line of the first half of the welding port until the bottom sealing welding of the whole pipe orifice is finished on the welding line of the end position of the first half of the welding port. The root welding requires attention to fusion of the lining plate and the groove part of the square steel pipe, and ensures that the welding flesh is between 3 and 3.5 mm.

And (3) filling layer process: before filling welding, the convex part on the first welding bead and the splash dust adhered on the slope wall should be removed, and the existence of fusion and concave included angle of the edge of the groove should be carefully checked, if the phenomenon is the phenomenon, an angle grinder must be used for removing, and the edge of the groove must not be injured. The interlayer temperature of the welding seam is always controlled between 120 ℃ and 150 ℃, the welding process is required to have stronger continuity, the interlayer temperature is reduced due to the repair defect in the welding process and the stop welding condition required by the cleaning welding bead, and a heating tool is required to be used for heating until the specified value is reached, and then the welding can be performed. When the cover surface is close to the cover surface, the depth of 1.5-2mm is uniformly reserved, so that the fusion condition of the two sides can be clearly observed when the cover surface is convenient.

The surface layer process comprises the following steps: the welding method is characterized in that a current value and a voltage value which are moderate by a small-diameter welding rod are selected, the fusion time at two sides of a groove is slightly long, a horizontal fixing port does not adopt a plurality of surface seams, a vertical fixing port and an inclined fixing port need to adopt multi-layer multi-pass welding, the multi-pass welding is strictly executed, and the surplus height of the welding seam which is strictly forbidden (2-2.5 mm outside the groove is controlled) is kept to be 0.5-3.0mm. The key points are as follows: (1) In the surface layer welding process, in order to prevent the excessive weld bead height from being excessively large due to the too thick weld bead, the welding is performed by adopting a larger welding voltage. (2) In order to control the increase of the carbon content of metal in the welding line, a carbon arc gouging machine is reduced in the process of cleaning the welding line so as to avoid cracking caused by the increase of the carbon content of the welding line due to the fact that high carbon grains attached to the surface of the welding line cannot be removed after the gouging is avoided.

(2) Welding process for steel pipe and hollow ball

The steel tube and the hollow sphere are welded by full penetration welding with a lining tube, as shown in fig. 19, 20 and 21.

1) The butt welding seams of the steel pipes are primary welding seams;

2) The full penetration butt weld and the full penetration split weld used for raw material splicing are primary welds;

3) The butt welding seams of the other components are secondary welding seams;

4) The fillet weld grade is a three-level weld, and the appearance detection quality grade is a two-level weld;

5) All welding seams should be subjected to appearance inspection, and the detection result accords with the specification of the current national standard of welding Specification for Steel structures GB50661, namely, nondestructive inspection is carried out on the first-stage welding seam and the second-stage welding seam, wherein the flaw detection proportion of the first-stage welding seam is 100%, and the flaw detection proportion of the second-stage welding seam is 20%. The flaw detection method and the flaw classification should respectively meet the related requirements of the current industry standard ultrasonic flaw detection and quality classification method of steel structure JG/T203.

Welding process

The welding method comprises the following steps: CO2 semiautomatic welding or manual arc welding;

Welding equipment: semi-automatic CO2 welding machine for loosening YD-500KR

Or a rectenna ZGX-500;

Welding materials: ER50-3 or E50× (Φ3.2, Φ4.0);

Welding parameters

Welding voltage: 28-30V (CO 2 welding) or 21-25V (manual welding);

Welding current: 250-320A (CO 2 welding) or 160-200A (manual welding phi 3.2) 180-220A (manual welding phi 4.0);

4. Post-weld stress relief

The stress reduction process is various, and mainly comprises a mechanical stress reduction method, a flame stress reduction method, an explosion stress reduction method and the like, wherein the conventional stress reduction method is a mechanical stress reduction method and a flame stress reduction method according to the construction characteristics of the steel structure industry.

The engineering adopts a hammering stress relief method to reduce the post-welding stress. The hammering method mainly adopts a small hammer to hammer the welded seam, and the hammering is used for reducing the welding stress.

5. Nondestructive testing of weld joints

After the appearance inspection of the welding seam is qualified, cooling is carried out for 24 hours, after the crystal phase structure of the steel is stabilized, ultrasonic nondestructive inspection is carried out on the welding seam according to the design requirement, a manual ultrasonic flaw detection method and result grading of the GB11345-89 steel welding seam are carried out, and a flaw detection report is provided after a specified inspection grade. In order to ensure the timely discovery of the post-welding tearing phenomenon, representative important bearing nodes are selected for tracking, rechecking and monitoring, the detection is carried out once a day, the detection is continued for 30 days, and the rechecking results are summarized.

6. Welding process control

(1) Inspection of welding process

Before welding: before welding, checking a component mark, confirming the installation precision of the component, checking welding materials, cleaning the site and preheating;

welding: maintaining the interlayer temperature, checking the filling material, bottoming the appearance of the weld, cleaning the weld bead, and welding according to welding parameters of a welding process;

after welding: removing welding slag and splashes, treating weld joint appearance, undercut, weld flash, cracks and arc pits, and cooling;

(2) Positioning welding

1) The welding material and the welding process requirements adopted by the positioning welding seam are the same as those of the formal welding seam.

2) Welding of the positioning welding seam should avoid welding at the beginning, the end and the corners of the welding seam, the arc pit should be filled, and the arc striking and the arc extinguishing on the base metal outside the welding area are forbidden.

3) The tack weld dimensions are required to perform as follows:

4) The fillet size of the tack weld should not be greater than 2/3 of the design size of the weld and not greater than 8mm, but not less than 4mm.

5) When the weld joint of the positioning welding has defects of cracks, air holes, slag inclusion and the like, the weld joint must be removed and then welded again.

7. Ultrasonic flaw detection work flow for seam

Scheme 1: the nondestructive inspection is performed on the basis of the appearance inspection being qualified.

Scheme 2: the personnel performing the nondestructive testing of the weld joint holds a nondestructive testing class II or more qualification certificate.

Scheme 3: and after the welding seam is cooled for 24 hours after welding, 100% detection is carried out on the full penetration primary welding seam according to the design requirement. The ultrasonic flaw detection method and the evaluation standard are carried out according to the manual ultrasonic flaw detection method and flaw detection result analysis of steel welding lines (GB 1231).

Scheme 4: and after the self-checking is qualified, monitoring and detecting or sampling by a third party of a supervision and owner organization.

8. Welding quality assurance measures

(1) Quality assurance measures

Measure 1: and a protective shed is arranged before welding construction.

Measure 2: the flux-cored wire is used for welding, and high-flow CO2 gas is used for welding protection, so that the stiffness of a CO2 protection gas column is increased, the wind resistance is improved, and the slag-gas combined protection of a welding pool is formed.

Measure 3: before welding, cleaning the welded junction, and removing water, oxide skin, rust and greasy dirt on the surface of the welded junction.

Measure 4: welding is performed strictly according to the welding process evaluation of the obtained parameters.

Measure 5: the interlayer temperature is strictly controlled in the welding process.

Measure 6: the slag removal between the weld beads must be thorough.

(2) Welding notice

1) Windproof measure

Welding operation area wind speed: the manual arc welding is not required to exceed 8m/s, the CO ₂ gas shielded welding is not required to exceed 2m/s, and otherwise, wind prevention measures are adopted.

The welding operation platform is utilized to make the platform into a basically closed state, so that the influence of strong wind on welding can be effectively prevented.

The periphery of the operation protective fence is sealed by flame-retardant materials, and the operation protective fence is rainproof and windproof.

2) Rain-proof, moisture-proof measures

The welding needs to be continuously performed, and if the welding meets the winter cold condition, the welding construction is influenced. Therefore, special measures of rain prevention, wind prevention and cold prevention are adopted.

As the operation platform is made to be totally closed, the welding point can avoid direct rain. However, rain water may flow down the pipe into the weld area, causing the weld area to quench.

A rain-proof shed is arranged above the welding area, and the periphery of the uppermost part of the surrounding pipe is blocked by adopting a waterproof material, so that rainwater cannot flow down.

3) Other considerations

And (3) strictly prohibiting arc striking on a base material except a welding line, and adopting measures such as symmetrical welding and the like to strictly control welding deformation during welding.

The tack welding must be performed by a worker who holds the welder's certification, and should be as demanding as the official weld.

And (3) implementing multi-layer multi-pass welding, cleaning welding slag and surface splashing in time after each welding process, and cleaning repair welding in time when defects affecting welding quality are found.

If the arc striking plate and the arc receiving plate are arranged, the arc striking plate and the arc leading-out plate are required to strike and receive the arc. After the welding is finished, the arc striking plate and the leading-out plate are cut off by using gas cutting, the width of the arc striking plate and the leading-out plate is kept to be 2mm, and the arc striking plate and the leading-out plate are polished and flattened by a grinder. Hammer drop is strictly disabled.

After welding, the surface splash and slag of the welding seam should be carefully removed, the defects of undercut, air holes, cracks, weld flash and the like should not be caused, the base metal should not be damaged by cutting the connecting plate and planing the backing plate, and the surface of the connecting plate, the leading-in plate and the leading-out plate after planing should be flat and smooth.

(3) Weld repair measures

Measure 1: before repairing, a repairing scheme is written, and the repairing scheme can be implemented after approval of a report supervision engineer after approval of an engineering technology responsible person.

Measure 2: the process and quality requirements of repairing the welding seam are the same as those of the welding seam, the number of times of repairing the same part of the welding seam is not suitable to exceed twice, if the welding seam is still unqualified after two times of repairing, a repairing scheme is required to be newly prepared, and the welding seam can be implemented after design agreements.

Measure 3: when in repair welding, arc striking should be carried out in the groove, and when arc extinguishing should be carried out, arc pits should be filled; the interlayer joints of the multi-layer welding should be staggered.

Measure 4: the repair part should be welded continuously, for example, when the welding is interrupted, post heat and heat preservation measures should be taken to prevent cracks.

Measure 5: the preheating temperature for welding repair should be higher than that for normal welding under the same conditions.

Measure 6: the repairing weld joint should be filled with repairing construction records and nondestructive testing reports before and after repairing, and used as engineering acceptance and archiving data.

Step 3, analyzing calculation book and hydraulic lifting working condition

Step 3.1 analysis calculation model

The engineering steel structure adopts hydraulic lifting, and specific construction steps of lifting are seen in construction organization design files of installation units. The calculation is carried out only by calculating the stress reaction, deformation condition, structural stability, supporting counterforce and the like of the steel structure and temporary measures in the lifting process. (the existing lifting calculation already considers purlin and support bracket in the lifting structure scope)

The engineering adopts SAP2000 for analysis, SAP2000 is an internationally universal finite element calculation analysis program, has powerful calculation analysis function, and can adopt Chinese specifications for design and checking of structures.

According to the drawing, the components are Q355 and Q235 steel, and the temporary measure is Q355.

Step 3.2 load and load combination

Step 3.2.1 structural load value

According to the building construction load Specification (GB 50009-2012), the construction should mainly take into account the following loads and effects:

(1) Permanent load

The weight of the structure, namely the weight of the steel is 78.5kN/m ³, is automatically calculated by a program.

(2) Variable load

Wind load:

basic wind pressure (ten years met) takes a value of 0.25kN/m ²;

The ground roughness takes the value B class;

the wind vibration coefficient takes a value of 1.3;

the value of the air pressure altitude influence coefficient is 1.3;

the wind load is calculated as follows:

F_k＝β_z×μ_z×μ_s×W₀×A

The calculated total horizontal wind force is F _x＝80kN、F_y =60 kN.

Step 3.2.2 load combination

The load combination is calculated according to the following conditions selected in the unified design standard for building structure reliability (GB 50068-2018):

The vertical load is the steel structure lifting area dead weight 385t, the node coefficient is 1.3, and the horizontal load is the steel structure wind load.

The load subentry coefficient of the vertical load is 1.3, the subentry coefficient of the wind load is 1.5, and the following load combination is considered in the process of stress calculation:

(1)1.3DEAD+1.5LIVE+1.5×0.6WX

(2)1.3DEAD+1.5LIVE+1.5×0.6WY

(3)1.3DEAD+1.5×0.7LIVE+1.5WX

(4)1.3DEAD+1.5×0.7LIVE+1.5WY

When deformation is calculated, the following load combination is considered without considering the polynomial coefficient:

(1)1.0DEAD+1.0LIVE+1.0WX

(2)1.0DEAD+1.0LIVE+1.0WY

Step 3.2.3 support restraint

Lifting the lifting point, fixing in Z direction and forming XY direction spring.

Example 2

Test hall: a single-layer factory building adopts double-limb steel lattice columns and steel net frames. The plane size is 104mX74m, the 1-8/A-N axis is a double-limb lattice column, 38 single-limb sections are HN500 x 200 x 10 x 16 section steel, the column height is-1.75-17.55 m, the column spacing is 8.0m/12.0m, and the gable column spacing is 10.0m/11.0m. The central elevation of the lower chord of the net frame is 18.0m, two inter-column supports are arranged along the longitudinal direction of the factory building, one inter-column support is arranged on the gable surface, and buckling restrained supports are adopted for the inter-column supports.

The plane of the roof of the test workshop is positioned between 1-8 lines XA-N axes, and the plane size is 104m multiplied by 74m. The roof structure is a double-layer welded ball net frame, and the node type is a welded ball. Maximum span 104m. The maximum height of the net rack is 4.480m. The lower chords around the net frame are supported on the top of the steel lattice column through the support, and the elevation of the center of the support is +18.000m. The material type of the roof net rack is steel pipes. The specification range of the steel pipe is P76 multiplied by 3.75 to P245 multiplied by 16mm, the maximum single rod weight of the rod piece is 353.88kg, and the specification range of the welding ball with the maximum length of 5.5 meters is WS3008-WSR8035. The total weight of the grid structure is about 425t.

The total weight 406t of the lifting part (including purlines and support brackets in the lifting range) is lifted to a height of about 18m.

The plane of the roof of the test workshop is positioned between 1-8 lines XA-N axes, and the plane size is 104m multiplied by 74m. The roof structure is a steel net frame, and the node type is a welding ball. Maximum span 104m. The maximum height of the net rack is 4.480m. The lower chords around the net frame are supported on the top of the steel lattice column through the support, and the elevation of the center of the support is +18.000m.

The material type of the roof net rack is steel pipes. The steel pipe specification range is P76X 3.75-P245X 16mm, and the welding ball specification range is WS3008-WSR8035. The total weight of the grid structure is about 425t.

The total weight 406t of the lifting part (including purlines and support brackets in the lifting range) is lifted to a height of about 18m.

Example 3

Based on example 1 and example 2, a step 4 stress analysis was performed

(1) From the analysis, the maximum span of the steel structure is 110000mm, the deflection of the engineering steel structure is controlled within 275mm (the deflection calculation formula is L/400, L is the span of the steel structure), the maximum vertical deformation of the steel structure is 110mm, the maximum stress ratio of the structure is 0.9, the stress values all meet the standard requirements, and the deformation value meets the standard requirements.

According to the steel structure design standard (GB 50017-2017), the maximum design stress ratio under the load effect combination of the bearing capacity limit state is 1.0.

(2) Checking and calculating temporary measures: the maximum stress ratio is 0.6, the maximum vertical deformation is 11mm, the maximum horizontal deformation is 33mm, and the requirement of lifting working conditions is met.

In conclusion, the deformation and stress of the structure in the whole lifting process meet the standard requirements.

9.8 Lifting and sling selection

1. Wire rope

The maximum weight of the hoisting member is about 0.41t, and 2-point hoisting is selected.

And checking sling:

the maximum lifting weight is about 0.41t, and when the included angle of the sling is considered according to 60 degrees, the stress of the steel wire rope is 2.4KN.

The formula:

[ Fg ] -allowable tension of wire rope Fg-sum of wire breaking forces of wire rope

The alpha-conversion coefficient and the safety coefficient of the 0.82K-steel wire rope are 8 when the hanging ring and the clamping ring are used for hanging.

Fg＝2.4*8/0.82＝23.4kN

The solution yields fg=23.4 kN. In order to consider the field hoisting safety, according to general technical condition of steel wire rope (GB/T20118-2017), the diameter of the steel wire rope is 8mm after checking, and the steel wire rope is a fiber core. 6 x 19 nominal tensile value is 1770Mpa steel wire rope. Can meet the hoisting requirement.

According to the data 34.8kN > 23.4kN, the hoisting requirement is met.

(2) Shackle for vehicle

According to the weight (0.41 t) of the maximum steel structural member, the bearing of the single shackle is 0.2t, and the single shackle is selected according to the safety factor of 2 times of bearing capacity.

The above detailed description of embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention.

Claims (2)

1. A steel mesh frame installation construction method is characterized in that: the method comprises the following steps:

Step 1: on-site assembly

Step 1.1: steel net frame assembly

The steel net frame is assembled and partitioned and assembled, and the assembling process comprises the following steps: step 1.1.1, setting temporary support assembly at the bottom, and fixing a lower chord ball of the net rack in a region; step 1.1.2, splicing the lower chords of the net rack in one area; step 1.1.3, fixing a chord ball on a net rack in a region; step 1.1.4, splicing web members of the net rack in one area; step 1.1.5, splicing upper chords of the net rack in one area; step 1.1.6, installing a lower chord member, a web member and an upper chord member of the second area net rack in sequence; step 1.1.7, splicing upper chords between two unit net racks; step 1.1.8, installing a third area net rack sequentially in the same way; step 1.1.9, assembling a fourth, fifth and sixth area net frame; step 1.1.10, lifting the roof truss and splicing the segmented truss on site; step 1.2.2, field assembly assurance measures;

(1) Assembly tire design and positioning

The design of the assembled jig frame needs to meet the strength requirement and the stability requirement;

(2) Assembling technical measures

1) Main measures for guaranteeing assembly quality

The method comprises the steps that 1, necessary assembling jig is adopted, after the assembling jig is arranged, the positions, radians, angles and the like of the jig are checked according to a construction drawing, and component assembling can be performed after retesting; 2, performing a welding process test, measuring an actual welding shrinkage coefficient, and guiding an actual welding process; 3, adopting advanced processing equipment to ensure blanking precision; the method comprises the steps of (4) performing accurate positioning on coordinates of all nodes of the net rack by using a total station in group positioning; measure 5, the maximum calculated deflection of the engineering net rack is 299mm, and the calculated deflection of the net rack under constant load is 237mm; the arch raising height of the net frame is 180mm, the arch raising height of the net frame is reflected on each supporting point, and the arch raising requirement of the net frame is finished by supporting steel pipes with different heights; after the assembly spot welding positioning, firstly checking the geometric dimension of the net rack, confirming that the welding can be started after the geometric dimension is checked, and the welding is strictly performed according to the welding process requirement; checking after assembling and welding are finished, and adopting various correction measures to ensure the use precision of the product; after the net rack is assembled on the jig frame, all constraints on the net rack are released, so that the net rack is in a free state, all dimensions of the net rack are measured in the free state, and the net rack is submitted to supervision for sectional acceptance;

2) Assembly detection measure

A measurement control point is established; before the mould is manufactured, the level of the reference surface of the platform is comprehensively measured by a level meter, records are made, the position of the measurement reference surface is determined according to data and actual conditions, and marks are made; taking the measured value of the bracket point into consideration when determining the height of the point, wherein the elevation error is less than or equal to +/-3.0 mm; measuring the verticality of the mould by using a total station, wherein the verticality is less than or equal to h/1000 and not more than 5mm, and the main control point is the elevation of the positioning point; carrying out actual re-inspection on the items by using a level gauge, a total station, a level bar and a steel rule; measure b, correcting and adjusting the card and the appliance; the correction mainly adopts a puller and a jack; measure c, detecting; (a) span, measurement tool: a steel ruler; (b) centerline and displacement, measuring means: theodolite, level gauge, total station, steel ruler; (c) elevation, measuring means: theodolite, level gauge, total station, steel ruler; (d) camber, measuring means: theodolite, level gauge, total station, steel ruler; when in field assembly, the measurement and control are carried out according to the arch lifting height, and the arch lifting value is carried out according to a deepened design drawing;

1.3 grid Assembly error control and cancellation

1.3.1 Design calculation for controlling and eliminating the assembling errors of the net frame

(1) The error sample is analyzed by adopting a computer, so that the error caused by the error sample is considered in the deepened design; (2) Calculating the values of thermal expansion and cold contraction according to the temperature change, and considering in the deepening design and construction process; (3) Positioning the nodes by using a laser total station, measuring after positioning one truss, measuring after assembling one truss, measuring after installing one section, and finally measuring after the whole section is completed;

1.3.2 on-site installation control measures for controlling and eliminating assembly errors of net rack

(1) The assembly of the lower chord of the integral net rack is started from the center, firstly, the vertical and horizontal shafts are assembled, the dimension is corrected at any time, the square can be unfolded from the center to the periphery when no error exists, the allowable error of the diagonal is required to be +/-3 mm, the offset of the lower chord node is 2mm, and the offset value of the vertical and horizontal of the integral net rack is not more than +/-2 mm; (2) Checking the geometric dimension after the assembly of the integral lower chord is finished, correcting by using a total station when necessary, adjusting the height difference of each point, and recording; (3) In order to facilitate construction and improve engineering progress, the web members and the upper chords of the lower chord assembly can be placed in a corresponding way according to the drawing and carried in place; (4) After the lower chord is assembled completely, the web members and the upper chord are assembled on the basis of no out-of-tolerance measurement, the method starts to assemble from the center, the geometric dimension of the longitudinal axis and the transverse axis is checked at any time, and the geometric dimension is corrected and then assembled around; (5) The spot welding is suitable for three points and the pipe diameter is large for four points when the net rack is assembled, and the arc striking is not required to be performed at any place except the joint of the rod piece and the node during the spot welding; (6) Before each lower chord node and upper chord node are welded, a level gauge and a steel tape are used for measuring height, levelness, geometric dimension and deflection, so that each lower chord node and upper chord node are qualified, and the whole is qualified; (7) Performing full-aspect repeated inspection once again for every three to five grids assembled so as to facilitate the timely treatment of the found problems; (8) After the whole assembly, carrying out one-time comprehensive inspection and measurement to ensure that no problem is left; in the whole net rack assembling process, attention is paid to the pad compaction of the lower chord ball, the accuracy of the axis, the quality of the welding line, the deflection and the control of the geometric dimension; the installation and the positioning of the support are one of grid control points, and the positioning by using a total station is accurate; the inspector checks the rod number, damage, geometric dimension, deflection and the like of the rod at any time in the installation process; after the net rack is installed, the net rack is inspected to be qualified, and then paint and fireproof paint can be brushed at one time, so that overhead operation is avoided; (9) The engineering net rack is a welded net rack, and the lower part of the net rack welded ball adopts temporary measure materials to control the height of the welded ball; for positioning of the grid ball nodes, a temporary supporting circular tube is arranged below the ball nodes due to space three-dimensional coordinate positioning, and temporary supporting measures are positioned and fixed at the bottom in advance for firm welding so as to support the ball nodes; in the assembling process of the net rack, electric welding and fixing are firstly carried out, and welding is carried out after measurement and alignment are accurate;

step 2: construction method

Step 2.1 Steel Structure welding construction

Firstly, building an assembly jig frame on the ground with the elevation of-0.500 m below the orthographic projection of a roof steel structure; 12 groups of lifting platforms are arranged on the double-limb steel lattice column top with the elevation of +17.550m, and each group of lifting platforms is provided with 1 XY-TS-75 hydraulic lifter, and the total number of the lifting platforms is 12; temporary lifting appliances, temporary rods and the like are arranged at positions of the lower chord of the roof net rack corresponding to the upper lifting points, and the upper lifting points and the lower lifting points are connected through special steel strands; lifting the whole lifting unit to a designed elevation by utilizing a hydraulic synchronous lifting system, installing a rear rod piece and the like, and removing the lifting platform, the reinforcing rod and the hydraulic synchronous lifting system; the position of the rear repair rod piece is occupied because the temporary lifting rod piece is welded with the welding ball, a connecting node is reserved in advance, and when the temporary rod piece is removed, a section is left after sealing treatment, so that the base material of the welding ball is prevented from being cut; finishing the installation operation of the roof steel structure;

step 2.2 Steel Structure lifting construction

Step 2.4 lifting of roof steel structure

1) Firstly, building an assembly jig frame on a ground layer with the elevation of-0.500 m below the orthographic projection of a roof steel structure; 2) Assembling the lifting part of the roof structure on the assembling jig frame to form an integral lifting unit; 3) 12 groups of lifting platforms are arranged on the double-limb steel lattice column top with the elevation of +17.550m, and each group of lifting platforms is provided with 1 XY-TS-75 hydraulic lifter, and the total number of the lifting platforms is 12; 4) Installing hydraulic synchronous lifting system equipment on a lifting platform, wherein the hydraulic synchronous lifting system equipment comprises a hydraulic pump source system, a lifter, a sensor and the like; 5) Temporary measures such as a temporary lifting appliance for lifting a lower lifting point and a temporary rod piece are installed at the position, corresponding to the upper lifting point, of the lower chord of the lifting unit; 6) Installing a special bottom anchor and a special steel strand between the lifting upper and lower lifting points; 7) Debugging a hydraulic synchronous lifting system; 8) Checking whether all temporary measures of the steel structure lifting unit and the hydraulic synchronous lifting meet design requirements; 9) After confirming that the error is not found, starting to try to lift; 10 Step-by-step loading according to the sequence of 20%, 40%, 60%, 70%, 80%, 90%, 95% and 100% of the designed load until the lifting unit is separated from the assembly jig frame; 11 After the integral lifting unit lifts about 100mm, the lifting is suspended; 12 Fine-tuning elevation of each lifting point of the lifting unit to enable the lifting unit to be in a designed posture, and standing for 2-24 hours; 13 Checking whether the steel structure lifting unit and the hydraulic synchronous lifting temporary measure are abnormal or not again before formal lifting; 14 After confirming no abnormal condition, starting formal lifting; 15 When the whole body is lifted to about 500mm away from the designed elevation, the lifting is suspended; 16 Measuring the actual elevation of each lifting point, comparing the actual elevation with the designed elevation, and making a record as a basis for continuously lifting the elevation; 17 The lifting speed is reduced, and the fine adjustment and inching functions of a hydraulic synchronous lifting computer control system are utilized to enable all lifting hanging points to reach the design position, so that the installation requirement is met; 18 Installing a net rack edge sealing rod piece to form a complete stress system; 19 The hydraulic synchronous lifting system sequentially and stepwise unloads according to the sequence of 95%, 90%, 80%, 70%, 60%, 50%, 40% and 20% of the design load until the steel strand is loosened, and the roof steel structure load is completely transferred to the column top support; 20 Removing the hydraulic lifting system and temporary measures to finish the lifting operation of the steel structure of the roof;

step 2.5 Steel Structure lifting installation

The steel structure lifting and installing process is as follows: step 1: assembling a grid lifting unit on the ground of-0.5 m, arranging a lifting platform by utilizing a lattice column and a frame structure, installing a temporary pipe for lifting a lower lifting point at a position corresponding to an upper lifting point of the lifting unit, and installing a hydraulic lifting system; step 2: debugging a hydraulic lifting system, performing trial lifting, starting formal lifting, integrally lifting the net rack to a designed installation position, and mounting a rod piece after the top of the column is repaired; step 3: after the structure is integrally stressed, the hydraulic lifter is unloaded in sequence, lifting equipment and temporary measures are removed, the residual rod pieces on the top of the column are supplemented, and the lifting operation is completed;

step 2.7 Steel Structure lifting installation construction requirement

Step 2.7.1 lifting the lifting Point set

According to the results of roof steel structure arrangement and working condition calculation, the roof steel structure lifting equipment is described: 1. the safety coefficients of the steel strands in the table are all larger than 2.0, so that the safety requirements are met; 2. the longest length of the steel strand is 24m, and the maximum weight of a single lifter plus the steel strand is 0.3t; 3. the steel strand is selected to have the specification ofThe breaking force of a single steel strand is 360kN, and the safety coefficient of the steel strand is=360/N (counter-force standard value/number); lifting the space coordinates of the lifting points;

step 2.7.2 lifting temporary measures

Lifting a large-span steel structure by adopting hydraulic synchronous lifting equipment, and setting reasonable lifting upper and lower lifting points; a hydraulic lifter is arranged on a lifting upper lifting point, namely a lifting platform; the hydraulic lifter is connected with a corresponding lower lifting point on the lifting steel structure through a special lifting steel strand; (1) a lifting platform arrangement; according to the structural formula of the position of the lifting point, the reaction force of the lifting point; (2) platform design; the lifting platform is supported by the lattice columns and the columns, and the temporary lifting measure mainly comprises a platform beam, upright columns and a horizontal structure according to the lifting process requirements and the structural characteristics; 1) The platform 1 is designed; 4 groups of platforms 1; the lifting device is suitable for lifting points D02, D03, D08 and D09, and the platform consists of a platform beam, brackets, upright posts and a horizontal structure; the temporary measure material is Q355B; the welding seam between the main force transmission components adopts a penetration welding seam, the welding seam grade is two, the thickness of all stiffening plates is 16mm, the welding seam between the stiffening plates and the platform beam adopts fillet welding, and the welding seam size hf=0.7t; 2) A platform 2 is designed; 8 groups of platforms 2; the lifting device is suitable for lifting hanging points D01, D04-D07 and D10-D12, and the platform consists of a platform beam, brackets, upright posts and a horizontal structure; the temporary measure material is Q355B; the welding seam between the main force transmission components adopts a penetration welding seam, the welding seam grade is two, the thickness of all stiffening plates is 16mm, the welding seam between the stiffening plates and the platform beam adopts fillet welding, and the welding seam size hf=0.7t; (3) temporary measures of the lower hanging point; 1) Reinforcing a lower hanging point; the lower lifting point is connected with the lifting unit through a temporary reinforcing rod; 2) Designing a temporary lifting appliance;

Step 2.7.3 guide frame setting

In the lifting or descending process of the hydraulic lifter, a steel strand growing out is reserved at the top of the hydraulic lifter, the hydraulic lifter is provided with a guide frame in advance, and the redundant steel strand can be freely dredged backwards and downwards along the lifting platform;

step 2.7.4 lifter fixation plate

After the hydraulic lifter is installed in place, the hydraulic lifter is immediately fixed by a temporary fixing plate; 4 temporary lifter fixing plates are needed for each hydraulic lifter; A. the surface B needs to be flat, so that the surface B can clamp the lifter base; the C surface is welded and fixed with the lower lifting platform beam, double-sided fillet welds are adopted in welding, the C surface cannot contact with the lifter base during welding, and the height of the welds is not less than 10mm;

step 2.7.5 temporarily lifting the reinforcement bar and the replacement bar

Step 2.8 preparation before lifting and inspection work

Step 2.8.1 temporary Lift means installation

12 Groups of temporary lifting frames are arranged on site in total, and the specific distribution and model number are required to be installed strictly according to the design requirements of the drawing; the lifting frame is machined by a workshop, welded into a whole, integrally hoisted by using an automobile crane on site, matched with a boarding car and used for ensuring the safety of aloft work; the bottom of the lifting frame and the top of the lattice column are subjected to full-penetration welding, and lateral supports are arranged to resist lateral stress;

Step 2.8.2 Steel strand installation

The steel strand penetrating method is adopted from bottom to top, namely the steel strand penetrates from the bottom to the top of the hydraulic lifter; the bottom of each bundle of steel stranded wires is leveled, and the upper ends of the penetrated steel stranded wires are fixed through the clamping heads and the anchor sheets; after the hydraulic lifter steel strand is installed, penetrating the lower end of the steel strand bundle into a bottom anchor structure of a lower lifting point corresponding to the right lower part, and locking after adjustment; the reserved steel strands at the top of each hydraulic lifter are led along the guide frame towards a preset direction;

Step 2.8.3 Hydraulic Elevator installation

After the hydraulic lifter is installed in place, the hydraulic lifter is immediately fixed by a temporary fixing plate; 4 temporary lifter fixing plates are needed for each hydraulic lifter; A. the surface B needs to be flat, so that the surface B can clamp the lifter base; the C surface is welded and fixed with the lower lifting platform beam, double-sided fillet welds are adopted in welding, the C surface cannot contact with the lifter base during welding, and the height of the welds is not less than 10mm;

step 2.8.4 mounting of special bottom anchor

Each hydraulic lifter corresponds to a set of special bottom anchor structure; the bottom anchor structure is arranged in the temporary lifting appliance for lifting the lower lifting point, and each set of bottom anchor is required to be vertically and correspondingly and concentrically arranged with the hydraulic lifter and the lifting point structure opening above the bottom anchor;

step 2.8.5 connection of hydraulic lines

The hydraulic pump source system is connected with an oil pipe of the hydraulic lifter: when connecting the oil pipe, the combined washer in the oil pipe joint should be taken out, and the corresponding pipe joint or the butt joint should be provided with an O-shaped ring; firstly connecting a low-position oil pipe to prevent oil in the oil pipe from flowing back; the hydraulic pump source system and the oil pipe between the hydraulic lifters are in one-to-one correspondence and are connected one by one; connecting oil pipes in parallel or in series according to a scheme to ensure correctness, and performing comprehensive review after connection; connection of control and power lines: the connection of various sensors; the hydraulic pump source system is connected with a control signal line between the hydraulic lifter; the hydraulic pump source system is connected with the computer synchronous control system; the hydraulic pump source system is connected with a power line between the distribution box; the computer control system is connected with a power line;

step 2.8.6 inspection and debugging of the device

(1) Checking before debugging; lifting temporary measure structure state inspection; checking equipment electricity, oil pipes and nodes; whether the temporary fixing measure of the lifting structure is removed; clearing obstacles influencing the lifting process; (2) system debugging; after the hydraulic system is installed, the debugging is carried out according to the following steps: checking whether joints of all valves or oil pipes on a hydraulic pump source system are loose or not, and checking whether pressure regulating springs of overflow valves are in a completely loosened state or not; checking whether the connection of a power line and a communication cable between the hydraulic pump source system control cabinet and the hydraulic lifter is correct or not; checking whether the oil pipe connection between the hydraulic pump source system and the main oil cylinder of the hydraulic lifter is correct or not; the system transmits power and checks whether the rotation direction of the main shaft of the hydraulic pump is correct; under the condition that the hydraulic pump source system is not started, corresponding buttons in the control cabinet are manually operated to check whether the actions of the electromagnetic valve and the stop valve are normal or not, and whether the stop valve number and the hydraulic lifter number are corresponding or not; checking the travel sensor to enable the corresponding signal lamp in the local control box to send a signal; checking before operation: starting a hydraulic pump source system, adjusting certain pressure, and expanding a main oil cylinder of a hydraulic lifter: checking whether the oil pipe connection of the cavity A and the cavity B is correct or not; checking whether the corresponding oil cylinder can be cut off by the cut-off valve;

step 2.9 hierarchical load test lifting

The main purpose of trial lifting is to confirm to accord with the calculation and design conditions of the simulation working conditions through the observation and monitoring of the lifting unit, the temporary lifting measure and the lifting equipment system in the trial lifting process, so as to ensure the safety of the lifting process; starting to try to lift after the hydraulic system equipment detects no errors; determining the cylinder extending pressure and the cylinder contracting pressure required by the hydraulic lifter according to the counter-force values of the lifting points calculated by computer simulation; when the test lifting is started, the cylinder extending pressure of the hydraulic lifter is gradually adjusted upwards, and is sequentially 20%,40% and 60% of the required pressure, and under the condition that all conditions are normal, the hydraulic lifter can be continuously loaded to 70%,80%,90%,95% and 100% until all lifting units are separated from the assembly jig frame; in the process of hierarchical loading, each step of hierarchical loading is completed, and the steps of: deformation conditions before and after loading of the upper hanging point, the lower hanging point structure, the lifting unit and the like, stability of the main body structure and the like; under all normal conditions, the next step of hierarchical loading is continued; when the step loading is carried out to the lifting unit and the lifting unit is about to leave the jig frame, various points are possibly lifted off simultaneously, the lifting speed is reduced, the situation that the points are lifted off is closely observed, single-point movement lifting is carried out when necessary, and the lifting unit is ensured to be lifted off stably;

step 2.10 formal lifting

In order to ensure the stability and safety of the lifting structure and the lifting process of the main body structure, a synchronous lifting and unloading landing control strategy of lifting point oil pressure balance, structure posture adjustment, displacement synchronous control and staged unloading in place is adopted according to the characteristics of the structure;

Step 2.10.1 synchronous lifting Point set-up

Each hydraulic lifter is provided with a set of travel sensor for measuring the synchronization of lifting displacement of each hydraulic lifter in the lifting process; the main control computer forms a closed loop system of a sensor, a computer, a pump source control valve, a lifter control valve, a hydraulic lifter and a lifting unit according to displacement detection signals of all the sensors and difference values of the displacement detection signals, and controls the synchronism of the whole lifting process;

Step 2.10.2 Structure off-ground inspection

After the lifting unit leaves the spliced jig frame for 100mm, locking by utilizing hydraulic lifting system equipment, staying in the air for 2-24 hours for comprehensive inspection, and reporting the inspection result to a site general command part in a written form; checking each item normally, and performing formal lifting;

step 2.10.3 posture check adjustment

Detecting the ground clearance of each lifting point by using a measuring instrument, and calculating the relative height difference of each lifting point; the height of each lifting point is adjusted through hydraulic lifting system equipment, so that the lifting unit reaches a design posture;

Step 2.10.4 integral synchronous lifting

Resetting the displacement sensor by taking the height of each lifting point after adjustment as a new starting position; in the whole lifting process, maintaining the gesture until the gesture is lifted to the vicinity of the designed elevation;

fine tuning of step 2.10.5 lifting process

In the lifting process, the height fine adjustment is required because of the adjustment of the aerial posture, the installation of the post-installed rod piece and the like; before the fine tuning starts, switching the computer synchronous control system from an automatic mode to a manual mode; according to the requirement, the hydraulic lifters of all lifting points in the whole hydraulic lifting system are subjected to synchronous inching, or the inching adjustment is carried out on a single hydraulic lifter; inching, namely inching adjustment precision reaches millimeter level, and the precision requirement of structure installation is met;

Step 2.10.6 lifting into position

When the lifting unit is lifted to 500mm away from the designed elevation, the lifting is suspended; fine tuning of each suspension point enables the structure to be accurately lifted to reach a design position; the hydraulic lifting system equipment pauses to work, the air posture of the lifting unit is kept, and a post-installed rod piece is installed, so that the lifting unit structure forms an integral stable stress system;

Mounting of the repair rod after step 2.10.7

The rear repair rod piece is hoisted by adopting a 25t automobile crane, enough space is reserved in advance, and collision with the installed component is avoided; the rear compensation rod piece is installed, the relative position of the rear compensation rod piece on the welding ball is marked in CAD, the intersection bottom is made, and the ground is assembled into a triangular cone and then is integrally hoisted; in order to control the overall stress of the net rack to be uniform, the installation sequence of the rear repair rod pieces is east-west symmetrical and north-south symmetrical, and the rod piece installation of lifting points is carried out after the rear repair rod pieces are installed;

Step 2.10.8 unloading of the lifting device

The installation of the roof net rack in the corresponding area is completed, and all welding seams and ball joints of net rack rod pieces are accepted; the hydraulic synchronous lifting system sequentially and synchronously unloads in a grading manner according to the sequence of 95%, 90%, 80%, 70%, 60%, 50%, 40% and 20% of the designed load until the steel strand is loosened, and the steel structure load is completely transferred to the steel structure support; removing hydraulic lifting system equipment and related temporary measures to complete integral lifting installation of the lifting unit; in the step-by-step unloading construction process, monitoring and measuring the displacement of each lifting hanging point by adopting a total station, and unloading the next stage after the abnormal analysis reason is found and adjusted;

Step 2.11 Net frame welding

Step 2.11.1 in-situ welding

Welding ball and member connection welding seam: when the wall thickness is less than 4mm, fillet welds are adopted, hf=1.5 tc, the welding strength is ensured to be equal to that of the rod piece, the grade of the welds is two-level, and the welds are made of ultrasonic waves for flaw detection materials and are subjected to specific quality proof and acceptance report; when the wall thickness of the steel pipe is more than or equal to 5mm, a short liner pipe is additionally arranged, the length is 50mm, and the wall thickness is 4mm; when the wall thickness of the steel pipe is more than or equal to 8mm, the steel pipe is reinforced by adopting partial fillet welds besides butt welds;

Step 2.11.2 welding preparation

1. Welding equipment selection

Carbon dioxide welding machine, use: full penetration butt welding of round steel pipes and box steel; spot welding the steel beam and the steel beam Niu Tuijie; carbon dioxide welding gun, use: the carbon dioxide welding gun is matched with the carbon dioxide gas shielded welding machine for use, and is detachable and convenient to construct; carbon arc gouging gun, use: the carbon arc gouging gun is used for repairing a welding seam, and the anode of the carbon rod is reversely connected; welding rod oven, use: a temperature-controllable welding rod oven is used for adjusting the baking temperature according to the requirement, so that the baking quality of the welding rod is ensured; the special person is on duty, and the electrode lead must be registered; infrared thermometer, use: detecting welding preheating temperature, interlayer temperature, post-heating temperature, heat preservation temperature and the like; weld detection complete equipment, use: a kit for testing during the process test; an alternating current arc welding machine, the application: installing and positioning welding the embedded part; temporary measures for component installation and correction are welded; other auxiliary welding; a carbon dioxide flow meter, use: the carbon dioxide flowmeter reflects the flow of carbon dioxide and is used for controlling the strength of shielding gas at the welding seam and heating the gas at constant temperature; air compressor machine, use: the carbon arc planer is matched with the air gun to provide high-pressure air for the air planer gun; the welding rod heat preservation cylinder is used: the portable welding rod heat preservation cylinder is used for heat preservation of welding rods in field welding, and can keep heat preservation continuously after power is inserted; a weld gauge, use: detecting grooves, gaps, welding heights, welding feet and arc pits; portable ultrasonic flaw detector, use: a steel internal defect nondestructive inspection professional instrument; operated by professionals of the corresponding qualification certificate;

Step 2.11.3 welding Process evaluation reference

(1) Manual arc welding parameter reference; (2) carbon dioxide arc welding parameter reference; (3) carbon dioxide arc welding parameter reference;

Step 2.11.5 in-situ welding procedure

1. Specific requirements of field welding operation; claim 1: welding: 1. adopting a welding mode of manual root welding bottoming and semi-automatic welding middle filling and capping; 2. the weldments with the lining plates are welded by adopting CO2 gas shielded semiautomatic welding; claim 2: the welding section is kept to be continuously welded, so that multiple arc extinction and arcing are avoided; when penetrating through the process hole at the mounting connecting plate, the joint must be sent through the center of the connecting plate, and the joint parts should be staggered; claim 3: when one or more pauses occur in the same layer of welding seam and welding is needed to be continued again, the initial welding head needs to be started at a position at least 15mm after the original arc-extinguishing position, and the direct arc starting at the original arc-extinguishing position is forbidden; when the CO2 gas shielded welding is in arc quenching, the welding gun can be removed after the shielding gas is completely stopped from being supplied and the welding line is completely condensed; removing the welding gun after the arc is forbidden to stop burning, so that the red-hot molten pool is exposed to the atmosphere and loses CO2 gas protection; claim 4: and (3) priming: igniting an electric arc on an arc striking plate 50mm in front of a welding seam starting point, and then carrying out welding construction by carrying out arc transportation; when the arc is extinguished, the arc is not allowed to be extinguished at the joint, but the arc is brought to an arc extinguishing plate which is 50mm beyond the joint to be extinguished, an arc pit is filled, the arc is transported by adopting a reciprocating type arc transporting method, the arc is slightly stopped at two sides, the included angle between welding flesh and a groove is avoided, and the gentle and excessive requirement is met; claim 5: and (2) filling layer: before filling welding, removing the convex part and the redundant part caused by arc striking on the first layer of welding bead, removing splashes and dust adhered on the sloping wall, and checking whether the edge of the groove is not fused or not and the included angle of the concave; when CO2 gas shielded welding is carried out, the gas flow is preferably controlled to be 40-55L/min, the welding wire is stretched to be 20-25mm, the welding speed is controlled to be 5-7mm/s, a molten pool is kept in a level state, a diagonal circle method is adopted in a welding operation, and when a layer is filled for welding a surface layer, the depth of 1.5-2mm is reserved, so that the bevel edge can be seen clearly when the surface layer is covered; claim 6: the surface layer welding directly relates to whether the appearance quality of the welding seam meets the quality inspection standard, the whole welding seam is repaired before welding, the concave-convex part is eliminated, and the continuous and uniform forming of the welding seam is maintained; when the surface layer weld joint is welded at the last weld joint, attention is paid to preventing the edge from generating undercut defects; claim 7: in the welding process: the interlayer temperature of the welding seam is always controlled between 100 ℃ and 150 ℃, the welding process is required to have maximum continuity, the repair defect occurs in the welding process, the welding is stopped when the welding slag is cleaned, the temperature is reduced, and a heating tool is required to be used for heating until the specified value is reached, and then the welding can be performed; when the welding seam has cracks, a welder cannot be treated without permission, a welding technology responsible person should be reported to find out the reason, and the welding technology responsible person can be treated after repair measures are taken; claim 8: post-weld cleaning and inspection: after welding, the spatter and welding slag should be removed, after the spatter and welding slag are removed, the appearance of the welding seam is checked by a welding seam gauge and a magnifying glass, the defects of sinking, undercut, air holes, unfused, cracks and the like cannot be caused, a post-welding self-checking record is made, a serial number steel seal of an operating welder is identified after the self-checking is qualified, the steel seal is identified at the position 50mm away from the longitudinal direction of the welding seam in the middle of the joint, and the identification at the edge is forbidden, so that the occurrence of a cracking source is prevented; the appearance quality inspection standard accords with the I-level specification of GB-50221 table 4-7-13; claim 9: nondestructive testing of welding seams: the weldment is cooled to normal temperature, nondestructive inspection is carried out, and the inspection standard accords with the specification of GB/T11345 Manual ultrasonic flaw detection method and quality grading method for steel weld joints;

2. Pre-weld preparation

Preparation 1: before assembling, rust and dirt are carefully removed from the 15-20mm inner wall of the groove at the joint by using a file, abrasive cloth and a disc steel wire brush; because the surface finish of the steel is poor, the concave part must be polished by an angle grinder before assembly, the surface of the groove has the phenomena of uneven and rusted, and the groove cleaning is the key point of the process; preparation 2: jacking up the gap of the groove at the joint by using a jack or other lifting appliance, and reserving welding shrinkage; checking whether the splicing gap, the misalignment state and the groove angle meet the requirements or not by using a steel ruler, an angle square, a wedge ruler and a welding seam gauge; preparation 3: the butt joint positioning welding adopts a small-diameter phi 3.2mm E5515 welding rod, the welding rod is baked according to the use specification, the welding length of the positioning welding is less than or equal to 50mm each time, and the thickness of the welding meat is about 4mm; preparation 4: grinding the initial welding and final welding positions into a gentle slope shape by adopting an angle grinder after positioning welding;

3. Welding construction process

(1) Welding construction process

The bottom layer process comprises the following steps: when the butt joint is welded at the root, the arc starting is carried out from the 10mm position of the central line of the lowest part of the welding mouth to the central line of the highest part of the component mouth exceeding about 10mm, the bottom sealing welding of half the welding mouth is completed, the first half of the initial welding and the final part of the welding mouth are polished into a gentle slope shape by an angle grinder before the other half of the welding, and after no unfused phenomenon is confirmed, the arc starting is carried out on the welding seam of the first half of the welding mouth until the welding seam of the end part of the first half of the welding mouth is finished; the root welding needs to pay attention to the fusion of the lining plate and the groove part of the square steel pipe, and ensures that the welding flesh is between 3 and 3.5 mm; and (3) filling layer process: before filling welding, removing the convex part on the first welded weld bead and splash dust adhered on the slope wall, and carefully checking whether the edge of the groove is fused or not and the concave included angle, if the phenomenon is the phenomenon, an angle grinder is required to be used for removing, and the edge of the groove cannot be damaged; the interlayer temperature of the welding seam is always controlled between 120 ℃ and 150 ℃, the welding process is required to have stronger continuity, the interlayer temperature is reduced due to the defect repair and the welding stopping condition required by the cleaning welding bead in the welding process, and a heating tool is required to be used for heating until the specified value is reached, and then the welding can be performed; when the cover surface is close to the cover surface, the depth of 1.5-2mm is uniformly reserved, so that the fusion condition of the two sides can be clearly observed when the cover surface is covered; the surface layer process comprises the following steps: selecting proper current and voltage values of a small-diameter welding rod, and paying attention to slightly long fusion time at two sides of a groove, wherein a horizontal fixing port does not adopt a plurality of surface seams, a vertical fixing port and an inclined fixing port need to adopt multi-layer multi-pass welding, the multi-pass welding is strictly executed, and the ultra-wide surplus height of the welding seam is strictly forbidden to be kept at 0.5-3.0mm; the key points are as follows: (1) In the surface layer welding process, in order to prevent the excessive weld bead height from being excessively large due to the too thick weld bead, a larger welding voltage is selected for welding; (2) In order to control the increase of the carbon content of metal in the welding line, a carbon arc gouging machine is reduced in the process of cleaning the welding line so as to avoid cracking caused by the increase of the carbon content of the welding line due to the fact that high carbon grains attached to the surface of the welding line after the gouging cannot be removed;

(2) Welding process for steel pipe and hollow ball

The steel tube and the hollow ball are welded by full penetration welding with a lining tube; 1) The butt welding seams of the steel pipes are primary welding seams; 2) The full penetration butt weld and the full penetration split weld used for raw material splicing are primary welds; 3) The butt welding seams of the other components are secondary welding seams; 4) The fillet weld grade is a three-level weld, and the appearance detection quality grade is a two-level weld; 5) All welding seams should be subjected to appearance inspection, and the detection result accords with the specification of the current national standard of welding Specification for steel structures GB50661, namely, nondestructive inspection is carried out on the first-stage welding seam and the second-stage welding seam, wherein the flaw detection proportion of the first-stage welding seam is 100%, and the flaw detection proportion of the second-stage welding seam is 20%; the flaw detection method and the flaw classification should respectively meet the related requirements of the current industry standard J G/T203 of ultrasonic flaw detection and quality classification method of steel structure;

4. Post-weld stress relief

The stress reduction process is of various types, and mainly comprises a mechanical stress reduction method, a flame stress reduction method, an explosion stress reduction method and the like, wherein the conventional stress reduction method is a mechanical stress reduction method and a flame stress reduction method according to the construction characteristics of the steel structure industry; the engineering adopts a hammering stress eliminating method to reduce the post-welding stress; the hammering method mainly adopts a small hammer to hammer welded seams, and the hammering is used for reducing welding stress;

5. Nondestructive testing of weld joints

After the appearance inspection of the welding seam is qualified, cooling for 24 hours, after the crystal phase structure of the steel is stabilized, carrying out ultrasonic nondestructive inspection on the welding seam according to the design requirement, executing a manual ultrasonic flaw detection method and result classification of the GB11345-89 steel welding seam, defining the inspection grade and providing a flaw detection report; in order to ensure the timely discovery of the post-welding tearing phenomenon, selecting representative important bearing nodes for tracking, rechecking and monitoring, detecting once a day, continuously detecting for 30 days, and summarizing rechecking results;

6. welding process control

(1) Inspection of welding process

Before welding: before welding, checking a component mark, confirming the installation precision of the component, checking welding materials, cleaning the site and preheating; welding: maintaining the interlayer temperature, checking the filling material, bottoming the appearance of the weld, cleaning the weld bead, and welding according to welding parameters of a welding process; after welding: removing welding slag and splashes, treating weld joint appearance, undercut, weld flash, cracks and arc pits, and cooling;

(2) Positioning welding

1) The welding material and the welding process requirements adopted by the positioning welding line are the same as those of the formal welding line; 2) Welding of the positioning welding seam should avoid welding at the beginning, ending and corners of the welding seam, the arc pit should be filled up, and arc striking and arc extinguishing on the base metal outside the welding area are forbidden; 3) Positioning welding size; 4) The welding leg size of the positioning welding is not more than 2/3 of the design size of the welding seam, is not more than 8mm, but not less than 4mm; 5) When the weld joint of the positioning welding has defects such as cracks, air holes, slag inclusion and the like, the weld joint must be removed and then welded again;

7. ultrasonic flaw detection work flow for seam

Scheme 1: nondestructive testing is performed on the basis of qualified appearance inspection; scheme 2: the personnel performing the nondestructive testing of the welding line holds a nondestructive testing II-level or more qualification certificate; scheme 3: after the welding seam is cooled for 24 hours after welding, 100% detection is carried out on the full penetration primary welding seam according to the design requirement; the ultrasonic flaw detection method and the evaluation standard are executed according to the manual ultrasonic flaw detection method and flaw detection result analysis of the steel weld seam; scheme 4: after the self-inspection is qualified, monitoring and detecting or sampling by a third party of a supervision and owner organization;

8. welding quality assurance measures

(1) Quality assurance measures

Measure 1: a protective shed is built before welding construction; measure 2: the flux-cored wire is used for welding, and high-flow CO2 gas is used for welding protection, so that the stiffness of a CO2 protection gas column is increased, the wind resistance is improved, and the slag-gas combined protection of a welding pool is formed; measure 3: before welding, cleaning a welded junction, and removing water, oxide skin, rust and greasy dirt on the surface of the welded junction; measure 4: welding the obtained parameters strictly according to the welding process evaluation; measure 5: the interlayer temperature is strictly controlled in the welding process; measure 6: the slag removal between the weld beads must be thorough;

(2) Welding notice

1) Wind-proof measures; 2) Rain-proof and moisture-proof measures;

step 3, analyzing calculation book and hydraulic lifting working condition

Step 3.1 analysis calculation model

The steel structure is lifted by adopting hydraulic pressure, and the concrete construction steps of the lifting are shown in construction organization design files of an installation unit; the calculation is carried out only by calculating the stress reaction, deformation condition, structural stability, supporting counterforce and the like of the steel structure and temporary measures in the lifting process; the SAP2000 is adopted for analysis, the SAP2000 is an internationally universal finite element calculation analysis program, the calculation analysis function is powerful, and the structure can be designed and checked by adopting Chinese specifications; according to the drawing, the components are Q355 and Q235 steel, and the temporary measure is Q355;

step 3.2 load and load combination

Step 3.2.1 structural load value

According to building structure load specification, the following loads and actions are mainly considered: (1) permanent load: the weight of the structure is 78.5kN/m ³ according to the weight of the steel, and the weight is automatically calculated by a program; (2) wind load: basic wind pressure (ten years met) takes a value of 0.25kN/m ²; the ground roughness takes the value B class; the wind vibration coefficient takes a value of 1.3; the value of the air pressure altitude influence coefficient is 1.3; the wind load is calculated as follows: f _k＝β_z×μ_z×μ_s×W₀ ×a; calculating the total horizontal wind power to be F _x＝80kN、F_y = 60kN;

step 3.2.2 load combination

The load combination is calculated according to the following conditions selected from the unified design standard of building structure reliability: the vertical load is the self weight 385t of the steel structure lifting area, the node coefficient is 1.3, and the horizontal load is the wind load of the steel structure; the load subentry coefficient of the vertical load is 1.3, the subentry coefficient of the wind load is 1.5, and the following load combination is considered in the process of stress calculation:

1.3DEAD+1.5LIVE+1.5×0.6WX；1.3DEAD+1.5LIVE+1.5×0.6WY；

1.3DEAD+1.5X0.7LIVE+1.5WX; 1.3DEAD+1.5X0.7LIVE+1.5WY; when deformation is calculated, the following load combination is considered without considering the polynomial coefficient: 1.0DEAD+1.0LIVE+1.0WX;1.0DEAD+1.0LIVE+1.0WY

Step 3.2.3 support restraint

Lifting the lifting point, fixing in Z direction and forming XY direction spring.

2. The steel mesh frame installation construction method according to claim 1, wherein:

step4 stress analysis

(1) From the analysis, the maximum span of the steel structure is 110000mm, the deflection of the steel structure of the engineering is controlled within 275mm, the maximum vertical deformation of the steel structure is 110mm, the maximum stress ratio of the structure is 0.9, the stress values all meet the standard requirements, and the deformation value meets the standard requirements; according to the steel structure design standard, the maximum design stress ratio under the load effect combination of the bearing capacity limit state is 1.0; (2) checking temporary measures: maximum stress ratio is 0.6, vertical deformation is 11mm maximum, horizontal deformation is 33mm maximum, and the requirement of lifting working conditions is met; in conclusion, the deformation and stress of the structure in the whole lifting process meet the standard requirements;

(2) Hoisting and sling selection

(21) A steel wire rope: the maximum weight of the hoisting member is about 0.41t, and 2 points are selected for hoisting; and checking sling: the maximum lifting weight is about 0.41t, and when the included angle of the sling is considered according to 60 degrees, the stress of the steel wire rope is 2.4 KN: [ Fg ] -allowable tension of the steel wire rope Fg-sum of steel wire breaking force of the steel wire rope; the alpha-conversion coefficient is 0.82K-the safety coefficient of the steel wire rope, and 8 is taken when the hoisting ring and the clamping ring are used for hoisting; fg=2.4×8/0.82=23.4 kN; solving to obtain Fg=23.4kN; in order to consider the field hoisting safety, according to general technical condition of steel wire rope, the steel wire rope with the diameter of 8mm and fiber core is checked; 6 x 19 nominal tensile value is 1770Mpa steel wire rope; the hoisting requirement can be met; according to the data 34.8kN > 23.4kN, the hoisting requirement is met;

(22) Shackle: according to the weight of the maximum steel structural member, the bearing of the single shackle is 0.2t, and the single shackle is selected according to the safety coefficient of 2 times of bearing capacity.