CN109057392B - Construction method of steel structure for reinforcement - Google Patents

Abstract

The invention discloses a steel structure construction method for reinforcement, which is mainly used in the reinforcement and reconstruction of building structures in the field of building science and technology. Its structure includes a steel plate, the steel plate includes a top steel plate and a bottom steel plate, the top steel plate is located on the top surface of the concrete floor, the bottom steel plate is located on the bottom surface of the concrete floor, the top steel plate and the plate bottom The steel plates are aligned in the longitudinal direction, and the top steel plate and the bottom steel plate are fixedly installed at the edge of the opening on the concrete floor to realize the reinforcement of the concrete floor; A rigid connection device that connects the two. The steel structure space system of the invention is integrated with the concrete floor, the anchoring effect is good, the bearing capacity and rigidity can be greatly improved; the construction and installation are convenient, and the problem of steel plate anchoring is solved; low cost.

Description

A kind of steel structure construction method for reinforcement

technical field

The invention relates to the field of building science and technology, in particular to a steel structure construction method for reinforcement, which is mainly used in the reinforcement and reconstruction of building structures.

Background technique

In the reinforcement and reconstruction project of concrete structure engineering, sometimes it is necessary to open holes in the concrete floor due to the consideration of installing equipment and adding stairs later. The opening of the floor slab destroys the integrity of the original floor slab and reduces the bearing capacity of the floor slab; while the installed equipment and stairs increase the load on the floor slab, and reinforcement must be carried out to ensure the safety and applicability of the structure.

In the national standard "Code for Design of Concrete Structures" GB50010-2010, for new construction, when openings are reserved on the cast-in-place concrete slab, reinforcements are generally required to be added around the openings. When the openings are large, concrete beams can be added.

In the national standard "Code for Design of Reinforcement of Concrete Structures" GB50367-2013, there is no treatment method for rear openings. Among the existing reinforcement methods, only the method of increasing the section, attaching steel plates to the surface or composite fiber material (FRP) method can be applied.

Among the existing reinforcement methods, there is a method of adding profiled steel beams. This method is to place the profiled steel at the bottom of the slab to bear the load from the slab surface, which can improve the bearing capacity of the structure, but this method reduces the use clearance, and Supports need to be added at both ends of the steel beam.

Among the existing reinforcement methods, there is a reinforcement method in which steel plates are attached to the surface of the plate. In this method, the steel plates at the top and (or) bottom of the plate are deformed with the deformation of the plate and generate a certain tensile pressure to improve the bearing capacity of the plate. In the method, the steel plate is only deformed by the deformation of the floor slab, and cannot form a relatively independent space system.

However, the method of increasing the cross-section inevitably sacrifices the use space, and the methods such as surface sticking increase the stiffness of the floor to a small extent, and the improvement of the bearing capacity is limited.

There is a roof reinforcement leak-proof device, which adopts the roof leak-proof technology to make full use of the wafer-type flange to reinforce the roof, so that the cut edge of the hole is converted from line contact to surface contact, and the contact area is increased, so as to achieve the compression resistance of the panel roof. And the purpose of leakage prevention; there is a construction method for opening a prestressed floor in a structural reinforcement project. Steel member support pads are added inside the newly added opening, and anchors are installed and tensioned, which are used for prestressed reinforcement when the prestressed floor is opened. In the prior art, angle steel is used for reinforcement and reconstruction of shear wall openings, but the force of shear walls is different from that of floor slabs, and the transformation method cannot solve the problems caused by opening holes. Stress concentration problems caused by both sides of the floor slab.

None of the above existing technologies can strengthen the floor slab, increase its bearing capacity, and help to eliminate prestress.

SUMMARY OF THE INVENTION

In view of the above problems, in order to make up for the lack of bearing capacity of the concrete floor slab after the opening of the concrete structure in the reinforcement and reconstruction of the concrete structure, and to ensure the structural safety and applicability of the concrete floor slab after the opening of the cavity, the purpose of the present invention is to provide a steel structure space for reinforcement. system and construction method.

The technical solution adopted by the present invention to solve the technical problem includes: a steel structure space system for reinforcement, comprising a steel plate, the steel plate includes a plate top steel plate and a plate bottom steel plate, and the plate top steel plate is located on the top surface of the concrete floor, The bottom steel plate is located on the bottom surface of the concrete floor, the top and bottom steel plates are aligned in the longitudinal direction, and the top and bottom steel plates are fixedly installed at the edge of the opening on the concrete floor to achieve Reinforcement of concrete floor slabs; a rigid connecting device is arranged between the top steel plate and the bottom steel plate to connect the two, and two bolt caps arranged symmetrically up and down are arranged on the rigid connecting device, and the bolt caps are embedded in the concrete floor slab The size of one end of the bolt cap close to the top or bottom surface of the floor is larger than that of the other end. In order to reduce the stress concentration at the connection, a bolt cap is specially set. Due to the setting of the opening, the stress of the concrete floor around the opening is relatively concentrated, especially the At the top and bottom, bolt caps with one end larger than the other end are used to better disperse the stress to the steel structure space system through the bolt caps, effectively ensuring the service life of the open floor slab.

From the perspectives of economy, practicability and connection reliability, a further technical solution is: the rigid connection device is a steel bolt, two ends of the steel bolt are provided with threads, and the steel bolt passes through all the bolts at the same time. The top steel plate, the concrete floor plate and the bottom plate steel plate are used, and the two ends of the steel bolt are locked by nuts.

A further technical solution is: the connection between the steel plate and the steel bolt is respectively provided with a bolt cap, the bolt cap is a conical connecting piece between the steel plate and the steel bolt, and the bolt cap is arranged on the side opposite to the nut, For the convenience of processing, the bolt cap can be tapered, and the surface is provided with patterns or threads to increase the contact area with the floor.

In order to further constrain the relative displacement between the steel plate and the concrete floor, and avoid the slippage damage between the steel plate and the concrete floor, a further technical solution is: a structural glue is provided at the connection between the steel plate and the concrete floor, and the steel bolt is connected to the concrete floor. There is structural glue in the gap between them.

A further technical solution is: the steel plates are arranged in one direction or two directions along the opening of the concrete floor. When the concrete floor is designed according to the one-way slab, the steel structure space system with one-way arrangement can be adopted. , A two-way layout of the steel structure space system can be used. The so-called two-way layout means that horizontal and vertical steel plates are simultaneously arranged around the opening of the concrete floor.

In order to ensure the reliability of the reinforcement effect, a further technical solution is: the two ends of the steel plate extend to the ends of the concrete floor where the steel plate is located.

The steel plate for reinforcement is preferably a strip-shaped steel strip.

The technical solution of the present invention to solve the technical problem also includes: a construction method for reinforcing a steel structure space system, comprising the following steps:

Step 1): Set the positioning line for the installation position of the steel plate on the outside of the opening on the concrete floor;

Step 2): according to the positioning line, steel plates are arranged on both the top surface and the bottom surface of the concrete floor slab, the steel plate on the top surface of the floor slab is the top steel plate, and the steel plate on the bottom surface of the floor slab is the slab bottom steel plate;

Step 3): The top steel plate, the concrete floor and the bottom steel plate are fixedly connected into one through a rigid connection device.

A further technical solution is: the top steel plate, the concrete floor and the bottom steel plate are connected by steel bolts and structural glue, and the connection method includes the following steps:

Step a: Drill holes on the concrete floor where the steel plate needs to be installed, and drill holes with the same diameter and spacing on the steel plate;

Step b: Polish the position where the steel plate needs to be installed on the concrete floor so that it meets the requirements for sticking the steel plate;

Step c: rust removal on the sticking surface of the steel plate;

Step d: Paste the bottom steel plate of the slab, connect the steel bolt with the bottom steel plate by using the conical bolt cap, then inject structural glue between the steel bolt and the hole where the steel bolt is installed on the concrete floor, and then paste the top steel plate, and use The bolt cap connects the steel bolt and the top steel plate, and the bolt cap is a conical connecting piece between the steel plate and the steel bolt.

In order to exert the best reinforcement effect, a further technical solution is as follows: the positioning line is located at a position 50 mm to 100 mm outside the opening on the concrete floor.

In order to ensure that the drilling process is not affected by the existing steel bars, a further technical solution is: in the step a, the hole diameter of the holes drilled in the concrete floor is 4mm to 6mm larger than the diameter of the steel bolts, and the spacing is the spacing between the steel bars in the concrete floor. 1 to 3 times.

The beneficial effects of the present invention are:

1. The steel structure space system and the concrete floor slab are combined into one through the rigid connection device, the anchoring effect is good, and the bearing capacity and rigidity can be greatly improved; The problem of steel plate anchorage does not increase the cross-section of the concrete floor, does not occupy the use space, uses less steel, and has low cost.

2. The rigid connection device effectively restrains the relative displacement between the steel plate and the concrete. In addition, a structural adhesive is installed to avoid the slippage damage between the steel plate and the concrete. The steel structure space system is closely combined with the concrete floor through the structural adhesive and the rigid connection device to form The whole of the common force greatly improves the bearing capacity and stiffness of the structure.

3. The steel structure space system of the present invention has a simple structure and adopts a conical bolt cap, which can better solve the problem of stress concentration in the middle floor slabs on both sides of the hole due to the excavation of the hole, and is easy to popularize and implement.

Description of drawings

1 is a front view of an embodiment of the present invention;

FIG. 2 is a schematic three-dimensional structure diagram of an embodiment of the present invention;

FIG. 3 is a schematic cross-sectional structural diagram of the assembled steel plate and the concrete floor according to the embodiment of the present invention;

4 is a schematic structural diagram of a unidirectional arrangement according to an embodiment of the present invention;

5 is a schematic structural diagram of a bidirectional arrangement according to an embodiment of the present invention;

6 is a schematic structural diagram of a steel plate according to an embodiment of the present invention;

7 is a schematic structural diagram of a steel bolt, a bolt cap and a nut according to an embodiment of the present invention;

8(a) to 8(d) are force analysis diagrams of the embodiment of the present invention;

FIG. 9 is a load-deflection curve diagram of an embodiment of the present invention.

In the picture: 1 steel plate, 2 steel bolts, 3 bolt caps, 4 nuts, 5 concrete floor plates, 6 opening parts, 7 mounting holes.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments of the description:

As shown in Fig. 1, Fig. 2 and Fig. 3, a steel structure space system for reinforcement includes a steel plate 1, the steel plate includes a top steel plate and a bottom steel plate, and the top steel plate is located on the top surface of the concrete floor 5 , the bottom steel plate is located on the bottom surface of the concrete floor 5, the top steel plate and the bottom steel plate are longitudinally aligned, and the top steel plate and the bottom steel plate are fixedly installed on the opening part 6 of the concrete floor 5 The edge of the concrete floor slab 5 can be strengthened.

The steel plate 1 and the concrete floor 5 are connected by the steel bolt 2, the bolt cap 3 and the nut 4. As shown in FIG. 6, the steel plate 1 is provided with an installation hole 7 for the steel bolt 2 to pass through. There are holes for the steel bolts 2 to pass through. As shown in FIG. 7 , the steel bolt 2 is a stud, and the nut 4 is provided with a thread that matches the steel bolt 2. The steel bolt 2 passes through the top steel plate, the concrete floor 5 and the bottom steel plate at the same time. The ends are locked by the nut 4, and the bolt cap 3 is a conical connecting piece between the steel plate 1 and the steel bolt 2, which can reduce the stress concentration at the connection.

The connection between the steel plate 1 and the concrete floor 5 is provided with structural glue, and the gap between the steel bolt 2 and the concrete floor 5 is also filled with structural glue. The steel structure space system is closely combined with the concrete floor 5 through structural glue and steel bolts 2 to form a whole under common stress, which greatly improves the bearing capacity and stiffness of the structure.

When the concrete floor 5 is designed as a one-way slab, a steel structure space system with one-way arrangement can be used. As shown in Figure 4; when the concrete floor is designed according to 5 two-way slabs, a two-way layout of the steel structure space system can be used. The so-called two-way layout means that horizontal and vertical steel plates are simultaneously arranged along the circumference of the opening 6 of the concrete floor 5, as shown in Figure 5 shown.

Both ends of the steel plate 1 extend to the ends of the concrete floor 5 where the steel plate 1 is located, and the steel plate 1 for reinforcement is preferably a strip-shaped steel strip.

The construction method of the present embodiment is, comprising the following steps:

First prepare for reinforcement:

Step 1): locate the position where the concrete floor slab 5 is to be opened, and determine the specification, model, quantity and cross-sectional area of the vertical and horizontal reinforcement bars when the concrete floor slab 5 is opened by consulting the drawings and on-site investigation;

Step 2): Determine the cross-sectional area of the steel plate at the bottom of the plate according to the principle of equal-strength substitution in both vertical and horizontal directions, taking into account the impact of the weakening of the drilling of the steel plate 1 and a certain safety redundancy;

Step 3): The specification and cross-sectional area of the top steel plate are the same as those of the bottom steel plate;

Step 4): Both ends of the newly added bottom steel plate and top steel plate should extend to the end of the concrete floor 5 .

After the reinforcement preparation is completed, install the space system:

Step 5): Set the positioning line for the installation position of the steel plate 1 at the position of 50mm to 100mm outside the opening part 6, and drill holes in the vertical concrete floor 5. The diameter of the hole is 4mm to 6mm larger than the diameter of the steel bolt 2, and the spacing is the spacing between the steel bars in the concrete slab. 1 to 3 times the size of the hole, generally 150mm to 400mm, to ensure that the drilling process is not affected by the existing steel bars;

Step 6): polish the position where the steel plate 1 needs to be installed on the concrete floor 5 so as to meet the requirements of pasting the steel plate 1;

Step 7): Steel plates 1 are arranged on the top surface of the floor and the bottom surface of the floor around the opening 6, and several steel bolts 2 passing through the concrete floor 5 are used to connect between the upper and lower steel plates 1. The section size and length of the steel plate 1 It is related to the floor span and the size of the floor opening, which should be determined by calculation to ensure that the flexural bearing capacity and flexural rigidity of the steel structure space system are not less than the original concrete floor at the opening;

Step 8): Drill holes on the steel plate 1 to install the steel bolts 2. The installation holes 7 drilled on the steel plate 1 have the same diameter and spacing as the holes drilled on the concrete floor 5 in step 5). rust;

Step 9): configure the structural adhesive, the structural adhesive adopts the existing structural adhesive, and can be configured according to the instructions for use;

Step 10): Apply the structural glue evenly on the sticking surface, stick the steel plate at the bottom of the board, use the bolt cap 3 to connect the steel bolt 2 with the steel plate at the bottom of the plate, and then inject the structural glue between the plate hole and the steel bolt 2, and then paste it The roof steel plate, and the bolt cap 3 is used to connect the steel bolt 2 and the roof steel plate to form a steel structure space system, and the concrete floor 5 after the opening is reinforced by the steel structure space system.

The force-bearing situation of the present invention is analyzed below. The force-bearing analysis is described by taking the space system arranged in one direction as an example, and the reinforcement structure form is shown in Figure 4:

Assuming that the thickness of the floor slab is h, for the calculation of the span direction (the length direction of the concrete floor slab), the width of the opening is B, and the cross-sectional area of the truncated main reinforcement is nA _s . Stiffness changes.

First, the bearing capacity changes:

The loss of flexural bearing capacity of the floor slab after opening is approximately:

M ₀ =0.85f _y ·nA _s ·h ₀

In the formula: f _y is the tensile strength of the steel bars in the concrete floor 5;

h ₀ is the calculated thickness of the concrete floor, that is, the distance from the top of the slab to the centroid of the steel bar.

When using the steel structure space system, the steel plate type is -t×b (- means steel plate, t means thickness, b means width), then there are two steel plates at the bottom of the plate on both sides of the opening, and the bearing capacity can be improved as follows:

In the formula: f represents the tensile strength of the steel sheet 1 .

Second, the stiffness change:

Without considering the beneficial effect of reinforcement, the stiffness of the original concrete floor at the removed opening is:

where E _c is the elastic modulus of the concrete floor;

I ₀ is the converted section moment of inertia of the concrete floor.

Taking the one-way arrangement of steel plates 1 as an example, when the steel structure space system is used, the steel plate type is -b×t, and there are four steel plates 1 in total, so the stiffness provided by the steel plates 1 on both sides of the opening is:

In the formula: E _s is the elastic modulus of the steel plate;

I ₁ is the converted sectional moment of inertia of the space system composed of steel plates.

3. Reinforcement requirements:

It suffices that the increased bearing capacity and stiffness after reinforcement are not less than the bearing capacity and stiffness of the original concrete floor slab of the demolished opening. For one-way slabs, only a single direction of force may be considered; for two-way slabs, forces in two span directions should be considered.

That is, the conditions that need to be met for the set reinforcement steel structure space system are:

M ₁ ≥M ₀ ;

E _s ·I ₁ ≥E _c ·I ₀

When determining the section size and length of the steel plate, it is sufficient that the steel plate meets this condition.

Still taking the space system of unidirectional arrangement as an example, the present invention will be further described below in conjunction with the implementation effect of the present invention:

1. Experimental research:

The concrete floor has a span of 4200mm and a width of 2000mm. C30 concrete is used, the plate thickness is 120mm, and the internal reinforcement is 10@100 (the diameter of the steel bar is 10mm, and the spacing between the steel bars is 100mm). The width of the proposed opening is 1000mm, and the length (span direction) is 2000mm, which is considered according to the force of the one-way plate. The steel structure space system is used for reinforcement and reinforcement. The steel plate type is Q235 and the size is -t×b=-10×150.

(1) Calculation analysis:

1. The weakening of the floor after opening:

As shown in Figure 8(a), the flexural bearing capacity loss of the concrete floor is approximately:

M ₀ =0.85f _y ·nA _s ·h ₀ =0.85×300×10×78.5×90=18,015,750N·mm

As shown in Figure 8(b), the flexural stiffness loss of the concrete floor is approximately:

2. The steel structure space system is used for reinforcement and reinforcement, and the steel plate type is -t×b=-10×120.

As shown in Figure 8(c), the steel plates on both sides of the opening 6 (two steel plates at the bottom of the plate) can improve the bearing capacity as follows:

As shown in Figure 8(d), there are four steel plates at the bottom and top of the plate, so the stiffness provided by the steel plates on both sides of the opening is:

(2) Measured data

There are three test specimens in this test. Considering the one-way plate, the net span is 4200mm, the plate width is 2000mm, and the plate thickness is 120mm. Specimen A is an intact concrete floor; Specimen B is a concrete floor with a hole in the center, 2000 mm in the span direction and 1000 mm in the width direction of the slab, and no reinforcement measures are taken; Specimen C is based on Specimen B, using the The steel structure space system is reinforced and reinforced concrete floor, the reinforcement steel plate used in specimen C is Q235, and the size is -t×b=-10×150.

The load-bearing capacity and deflection deformation of the three specimens were tested by the method of grading loading on the top of the plate.

1. The bearing capacity is shown in the following table:

Specimen name Specimen A Specimen B Specimen C Breaking load kN/m 16.0 10.5 35.5

2. The deflection deformation is shown in Figure 9.

2. Analysis conclusion:

Through the above calculation and analysis, after the reinforcement and reinforcement of the present invention, the bearing capacity of the specimen C is increased by 250% compared with the unreinforced specimen B, and the bearing capacity of the concrete floor slab without holes (specimen A) is increased by 100%. ; Under the original design load of the plate (about 8kN/m), the deflection is 11% of that of specimen A and 42% of that of specimen B. The bearing capacity and stiffness are greater than those of the concrete floor before opening, which can meet the requirements of safe use.

The force analysis of the two-way plate is similar to this and will not be repeated here.

The structural adhesive in the present invention is not limited to the structural adhesive described in the embodiments, and other construction adhesives can also be used.

The above are only preferred embodiments of the present invention, not all embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention , should be included within the protection scope of the present invention.

Except for the technical features described in the description, other technical features are known to those skilled in the art, and in order to highlight the innovative features of the present invention, the above technical features are not repeated here.

Claims (3)

1. a construction method for reinforcing steel structure space system, is characterized in that, comprises the following steps: Step 1): Set the positioning line for the installation position of the steel plate on the outside of the opening on the concrete floor; Step 2): according to the positioning line, steel plates are arranged on both the top surface and the bottom surface of the concrete floor slab, the steel plate on the top surface of the floor slab is the top steel plate, and the steel plate on the bottom surface of the floor slab is the slab bottom steel plate; Step 3): The top steel plate, the concrete floor and the bottom steel plate are fixedly connected into one through a rigid connection device; The top steel plate, the concrete floor and the bottom steel plate are connected by steel bolts and structural glue, and the connection method includes the following steps: Step a: Drill holes on the concrete floor where the steel plate needs to be installed, and drill holes with the same diameter and spacing on the steel plate; Step b: Polish the position where the steel plate needs to be installed on the concrete floor so that it meets the requirements for sticking the steel plate; Step c: rust removal on the sticking surface of the steel plate; Step d: Paste the bottom steel plate of the slab, connect the steel bolt with the bottom steel plate by using the conical bolt cap, then inject structural glue between the steel bolt and the hole where the steel bolt is installed on the concrete floor, and then paste the top steel plate, and use The bolt cap connects the steel bolt and the top steel plate, the bolt cap is a conical connecting piece between the steel plate and the steel bolt, and the outer surface is provided with patterns or threads. 2 . The construction method according to claim 1 , wherein the positioning line is located at a position 50 mm to 100 mm outside the opening on the concrete floor. 3 . 3. construction method according to claim 1 is characterized in that, in described step a, the hole diameter of the hole in the concrete floor is larger than the diameter of the steel bolt by 4mm～6mm, and the spacing is 1～6mm of the spacing between steel bars in the concrete floor 3 times.

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