CN112049457A - Selection method of anti-vibration inhaul cable for historic building masonry column and anti-vibration inhaul cable system - Google Patents
Selection method of anti-vibration inhaul cable for historic building masonry column and anti-vibration inhaul cable system Download PDFInfo
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Abstract
The invention relates to the technical field of building construction, and discloses a selection method of a shockproof inhaul cable for an ancient building masonry column and a shockproof inhaul cable system. The method comprises the steps of selecting a stay cable according to design experience, then establishing a three-dimensional entity discrete element analysis model of a masonry column including the stay cable, solving by using a finite element method, and judging whether the cross section area required by the stay cable arranged at the top of the masonry column and the value of prestress to be loaded reach the standard or not. The gap in the field is filled, the stay cable can strengthen the shock resistance of the masonry column and simultaneously retain the ductility of the masonry column, and the guy cable can be applied to reinforcing of ancient buildings and can finish the reinforcing on the premise of conforming to the principle of minimum intervention and reversibility of building repair and protection.
Description
Technical Field
The invention relates to the technical field of building construction, in particular to a selection method of a shockproof inhaul cable for an ancient building masonry column and a shockproof inhaul cable system.
Background
The prestressed inhaul cable is an emerging reinforcing scheme for reinforcing the building, and the reinforcing scheme is particularly suitable for ancient buildings.
At present, the masonry ancient building in China is reinforced mainly by adopting a structure reinforcing mode, and a reinforcing device is embedded into a building body to reinforce the building. The method has the serious defects that although the safety performance of the historic building under normal use load and small earthquake can be enhanced, the original inherent energy consumption capability of the historic building under abnormal natural disasters such as major earthquake is limited, and the case that the earthquake damage degree is increased after the historic building is reinforced occurs in the past earthquake in recent years occurs. In addition, the original appearance of the unmovable cultural relics such as ancient buildings is maintained as much as possible to ensure the original reality of historical information, and the conventional reinforcing device and method are embedded into the cultural relic body, so that the principle of minimally interfering the cultural relic body is difficult to realize, and the safety of the cultural relics cannot be ensured.
The reinforcing of the historic building by the prestressed stay cable can not damage the building and does not influence the original appearance of the building. The guy cable with reasonable prestress can ensure the structural strength of the historic building and can ensure that the historic building structure has certain ductility energy consumption capability. However, the value of the applied prestress needs to be strictly calculated, and if the value of the prestress is not properly selected, the prestress cannot be used for strengthening, and damage can be caused to the building body.
However, the existing calculation method of the prestress applied by the prestress stay cable aims at reinforced concrete, calculation is required according to the number and the type of the steel bars, and no calculation method for a masonry structure is provided. The ancient building is not provided with reinforced concrete, only has a wood structure and a masonry structure, and is reinforced and reformed by the prestressed stay cable, which is mainly embodied in reinforcing the masonry structure in the ancient building, so that a calculation method applicable to the masonry structure is necessary to be developed.
Disclosure of Invention
The invention provides a selection method of a shockproof inhaul cable for an ancient building masonry column and a shockproof inhaul cable system.
The technical problem to be solved is that: the existing calculation method of prestress needing to be loaded in the prestress stay cable aims at reinforced concrete and is not a calculation method for masonry structures.
In order to solve the technical problems, the invention adopts the following technical scheme: the selection method of the shockproof inhaul cable for the historic building masonry column comprises the following steps:
the method comprises the following steps: establishing an analysis model of a masonry column containing a guy cable;
step two: setting the cross-sectional area and the prestress of the stay cable in the analysis model;
step three: applying horizontal load to the top of a masonry column in the analysis model from zero until the masonry column is damaged, and entering a fourth step if the compressive stress borne by the building block in the masonry column does not exceed the compressive strength of the building block all the time in the horizontal load increasing process; otherwise, returning to the step two;
step four: respectively judging whether the cross-sectional area of the stay cable reaches the standard in the horizontal load increasing process according to the requirement of the construction process on the strength allowance of the stay cable, if so, entering the fifth step, otherwise, returning to the second step;
step five: applying a horizontal seismic acceleration time course at the bottom of a masonry column in the analysis model to obtain the maximum shearing force applied to the masonry column under the action of the earthquake and the ratio of the maximum horizontal deformation to the height of the masonry column;
step six: and D, judging whether the prestress value set in the step two reaches the standard or not from the aspects of safety degree of horizontal bearing capacity and ductility control of horizontal deformation according to the calculation results of the step four and the step five, recording the cross sectional area and the prestress if the prestress value reaches the standard, and returning to the step two if the prestress value does not reach the standard.
Further, in the first step, a three-dimensional entity discrete element analysis model of the masonry column including the guy cable is established, and the self weight of the masonry column and the weight of an upper layer structure borne by the masonry column are taken into account during modeling; the connection units between the building blocks in the established analysis model comprise bonding strength and friction parameters between the building blocks.
Further, in the second step, prestress is applied to the inhaul cable by adopting a method of initial strain or negative temperature application, and the cross section of the inhaul cable is changedThe tensile strength of the inhaul cable is changed by multiplying the elastic modulus, and the prestress sigma in each inhaul cable is less than or equal to 0.2 sigmau，σuThe tensile strength of the stay cable; additional compressive stress value sigma generated by stay cable on masonry columnz≤0.15Mpa。
And further, in the third step, a load increment method is adopted to carry out material elastoplasticity and geometric nonlinear simulation analysis in the whole process of the masonry column structure, and the geometric nonlinear influence of the structural system is taken into account in the solving process.
Further, the step four comprises the following sub-steps:
step 4.1: drawing an F-S function curve in the analysis model by taking the horizontal deformation S of the masonry column as an independent variable and the horizontal load F as a dependent variable, and obtaining the maximum value F of the horizontal load in a linear interval on the F-S function curvekHorizontal load F when the masonry column begins to yieldyAnd horizontal deformation amount SyHorizontal load F when masonry column is damageduAnd horizontal deformation amount Su；
Step 4.2: respectively judging the horizontal load F-F of the stay cable according to the requirement of the construction process on the strength allowance of the stay cablek、F＝FyAnd F ═ FuAnd (5) judging whether the cross-sectional area reaches the standard, if so, entering the step five, and otherwise, returning to the step two.
Further, in substep 4.1, F was obtained as followsk、Fy、Sy、FuAnd Su：
Marking the X point as any point on the F-S function curve, the horizontal deformation value of the abscissa of the X point as S, and defining the area of a triangle formed by the connecting line of the original point O and the X, the perpendicular line passing through the X point and the S axis as F1(S) the area defined by the curve between the origin O and the X point, the perpendicular line passing through the X point and the S axis, and the S axis2(s), provided that γ is f1(s)/f2(s); recording a vertical coordinate horizontal load peak point F on a curve of the F-S functionmaxThe corresponding horizontal deformation value of the abscissa is S1Set point { A1，A2，……，Ai，……，AnIs a point on the F-S curve, n > i, with the abscissa {1/n, 2/n, … …，i/n，……，n/n}×S1Calculate point { A1，A2，……，Ai，……，AnThe gamma values of { gamma } are respectively1，γ2，……，γi，……，γnIf { gamma }, ifi，……，γnAll < theta, and gammai-1Is not less than theta, then Ai-1The ordinate of the point is Fk(ii) a Wherein n is more than or equal to 50, and the value range of the parameter theta is more than or equal to 0.96 and less than or equal to 0.98;
taking F on the F-S functionuThe abscissa of the maximum point M is SuThe ordinate is Fu；
Connecting the origin points O and Ai-1Extending to cross the horizontal line passing through M to point B, drawing a perpendicular line to the abscissa axis to cross the F-S function curve to point Y, and determining the abscissa of point Y as SyThe ordinate is Fy；
In substep 4.2, if F is the horizontal load F ═ FkIn time, the tensile stress borne by the stay cable does not exceed the tensile strength sigma of the stay cableu0.4 times of (1), horizontal load F ═ FyIn time, the tensile stress borne by the stay cable does not exceed the tensile strength sigma of the stay cableu0.6 times of (d), and the horizontal load F ═ FuIn time, the tensile stress borne by the stay cable does not exceed the tensile strength sigma of the stay cableu0.8 times of; then sigma is determineduReaching standard, otherwise, judging sigmauThe standard is not reached.
Further, in the fifth step, the direction of the seismic acceleration time course is arranged along the span direction of the upper-layer structure borne by the masonry column, and the following data are obtained according to the seismic grade:
maximum shearing force V of masonry column under action of multi-earthquakekThe ratio delta k/H of the maximum horizontal deformation to the height H of the masonry column, the ratio delta y/H of the maximum horizontal deformation to the height H of the masonry column under the action of a fortification earthquake, and the ratio delta u/H of the maximum horizontal deformation to the height H of the masonry column under the action of a rare earthquake; and the geometric nonlinear influence of the structural system is taken into account during solving.
Further, in step six, if Fu/Fy≥1.3，Su/Sy≥1.5，Fk/VkAnd when the stress value is more than or equal to 1.0, the delta k/H is less than or equal to 1/500, the delta y/H is less than or equal to 1/300, and the delta u/H is less than or equal to 1/200, judging that the prestress value reaches the standard, otherwise, judging that the prestress value does not reach the standard.
Further, the selection method further comprises the following steps:
step seven: and repeating the second step to the sixth step to obtain a plurality of groups of up-to-standard prestress values, and determining the value range of the up-to-standard prestress values.
The shockproof inhaul cable system is used for shockproof reinforcement of a masonry column in an ancient building, the masonry column is a top beam column, and the shockproof inhaul cable system comprises a U-shaped base plate and an inhaul cable, wherein the U-shaped base plate is downwards clamped on a cross beam above the masonry column in an opening mode, the middle of the inhaul cable is hung on the upper surface of the U-shaped base plate, and two ends of the inhaul cable are anchored on a fixed foundation;
the pull cable is connected with the U-shaped base plate through the fastener, is connected with the U-shaped base plate in a sliding mode when the fastener is loosened, and is fixedly connected with the U-shaped base plate when the fastener is locked;
the cross-sectional area of the inhaul cable and the loaded prestress are selected by the selection method.
Compared with the prior art, the selection method of the shockproof inhaul cable for the historic building masonry column and the shockproof inhaul cable system have the following beneficial effects:
according to the invention, by establishing the three-dimensional entity discrete element analysis model of the masonry column including the guy cable instead of analyzing the stress condition of the masonry column as a whole, the stress condition of the building block in the masonry column under the action of horizontal load is analyzed, and the selected guy cable is required to ensure that the compressive stress borne by the building block does not exceed the compressive strength of the building block all the time, so that the masonry column is prevented from being damaged after the guy cable is added, and the ancient building is prevented from being damaged and aggravated in the earthquake like the conventional ancient building reinforcing device.
In the invention, in the process of selecting the inhaul cable, not only the strength is considered, but also F is consideredu/Fy，Su/SyThe volume of waiting to be correlated with the ductility is brought into consideration, has considered the cable and has added the back, and the ductile change of brickwork post makes the cable can guarantee the structural strength of brickwork post, can make the brickwork post have certain ductility power consumption ability again.
In the invention, in the process of selecting the stay cable, the deformation condition of the masonry column under the earthquake action of different grades after the stay cable is added is considered, so that the masonry column can not be unstable or damaged under the earthquake action of different grades.
The invention provides a selection method of a shockproof inhaul cable for a masonry column of an ancient building and a shockproof inhaul cable system, which can be used for selecting the cross section area required by the inhaul cable arranged at the top of the masonry column and the value of prestress to be loaded, fills the blank of the field, enables the inhaul cable to strengthen the shock resistance of the masonry column and simultaneously keeps the ductility of the masonry column, and can be applied to strengthening of the ancient building to complete strengthening on the premise of conforming to the principle of minimum intervention and reversibility of building repair and protection.
Drawings
FIG. 1 is a schematic structural view of an anti-vibration cable system;
FIG. 2 is a schematic cross-sectional view of a masonry column;
FIG. 3 is a graph of the F-S function;
FIG. 4 is a 1952Taft Lincoln School seismic acceleration time course curve
Wherein, the building comprises 1-building block column, 2-beam, 3-U-shaped backing plate, 4-fastener and 5-inhaul cable.
Detailed Description
As shown in fig. 1, the shockproof inhaul cable system is used for shockproof reinforcement of a masonry column 1 in an ancient building, the masonry column 1 is a top beam column, and the shockproof inhaul cable system comprises a U-shaped base plate 3 with a downward opening clamped on a cross beam 2 above the masonry column 1 and inhaul cables 5 with middle parts hung on the upper surface of the U-shaped base plate 3 and two ends anchored on a fixed foundation; the inner side of the U-shaped backing plate 3 is processed into a rough surface so as to avoid slipping on the beam, and in addition, the inner side of the U-shaped backing plate 3 is padded with a plurality of soft pads so as to avoid crushing the beam 2;
in the embodiment, two ends of the inhaul cable 5 are anchored in the concrete foundation through the embedded plate with the anchor bar, and the inhaul cable 5 is hinged with the embedded plate with the anchor bar through the lug plate and the pin shaft;
the inhaul cable 5 is connected with the U-shaped base plate 3 through the fastener 4, is connected with the U-shaped base plate 3 in a sliding mode when the fastener 4 is loosened, and is fixedly connected with the U-shaped base plate 3 when the fastener 4 is locked; this construction has the advantage of facilitating uniform prestressing of the entire cable 5 during installation.
The fastener 4 in the embodiment is a clamping plate arranged on the edge of the U-shaped base plate 3, each edge of the U-shaped base plate 3 is provided with a pair of clamping plates, each pair of clamping plates are buckled through a bolt, the inhaul cable 5 is clamped in the clamping plates, and the clamping plates are provided with grooves which are in interference fit with the inhaul cable 5 after the clamping plates are clamped; one plate of each pair of clamping plates is welded on the U-shaped base plate 3;
in the embodiment, the U-shaped backing plate 3, the fastener 4, the bolt, the lug plate and the pin shaft are made of Q345B-grade steel; in the embedded plate with the anchor bars, the top plate is made of Q345B-grade steel, and the anchor bars are made of HRB 400-grade steel bars; the inhaul cable 5 is made of a zinc-5% aluminum-rare earth alloy coating high-strength steel cable.
The cross-sectional area of the stay 5 and the loaded prestress are selected by the following selection method:
step one, selecting a ancient building block column 1 and an upper wood roof truss structure, and establishing a three-dimensional entity discrete analysis model by using ABAQUS software. The height H of the masonry column 1 is 4.08m, and the section of the masonry column 1 is shown in figure 2. Modulus of elasticity E of the block1＝2×104MPa, compressive strength fk15MPa, the bulk density of the material is 18KN/m3Modulus of elasticity E of masonry mortar2＝6×103MPa, compressive strength fk21.2MPa, the bulk density of the material is 16KN/m3Coefficient of friction mu between block and masonry mortar10.7 and 0.5MPa for bond strength c. The top plate in the embedded plate with the anchor bars adopts Q345B-grade steel related parameters, the cross section of the stay cable 5 is circular, and the tensile strength sigma isu1670MPa, modulus of elasticity E3＝1.6×105The friction coefficient mu between the MPa U-shaped base plate 3 and the cross beam 220.35. Step two, selecting the cross section area and the prestress value of one group or a plurality of groups of guys 5 according to design experience, wherein the guys 5 in an analysis model in the step one are used for meeting the additional compressive stress value sigma generated on the masonry column 1zNot more than 0.25MPa, and the pulling stress sigma borne by the inhaul cable 5 is not more than 0.2 sigmau(σuIs the limit value of the tensile strength of the stay cable 5), prestress is respectively applied by adopting an initial strain method, and the applied strain value and the diameter of the selected stay cable 5 are formed as shown in the table4 analytical models.
TABLE 1 overview of the four models
And step three, respectively applying horizontal loads to the top of the masonry column 1 according to the 4 models established in the step one and the step two, performing material elastoplasticity and geometric nonlinear simulation analysis on the whole process of the masonry column 1 structure by adopting a load increment method, and gradually increasing the horizontal loads from zero to damage the masonry column 1. The analysis is solved by adopting a Newton-Raphson nonlinear iteration method, the geometric nonlinear influence of a structural system is taken into account, and the building block adopts a plain concrete Drucker-Prager elastoplastic model. In the whole loading process, in 4 analysis models, the maximum compressive stress fq borne by the building block is respectively 2.0MPa, 2.8MPa, 3.5MPa and 4.6MPa, and fq is more than fk1＝5MPa，fk1The compressive strength of the masonry is obtained. The parameters of the sintered bricks adopted by the ancient building are similar to those of the plain concrete bricks, and no model of the sintered bricks exists at present, so that a mature plain concrete Drucker-Prager elastoplastic model is selected to simulate the building blocks in the embodiment.
Step four, according to the analysis and calculation results in the step three, a function curve of the horizontal load F at the top of the masonry column 1 and the horizontal deformation S at the top of the masonry column 1 in the 4 models is drawn, and the function curve is shown in fig. 3. Horizontal load F when masonry column 1 is brokenuAnd horizontal deformation amount Su；
The horizontal load on the curve of the F-S function is called FkThe point of (A) is the maximum linear horizontal bearing capacity performance point, and the horizontal load on the curve of the F-S function is called FyThe yield point of the horizontal bearing capacity of the point (A) is called as the horizontal load on the curve of the F-S function (F)uThe point of horizontal bearing capacity extreme point. The method comprises the following steps: fk、Fy、Sy、FuAnd Su
Marking the X point as any point on the F-S function curve, the horizontal deformation value of the abscissa of the X point as S, and defining the area of a triangle formed by the connecting line of the original point O and the X, the perpendicular line passing through the X point and the S axis as F1(s) adding the origin O toThe area enclosed by the curve between the X points, the perpendicular line passing through the X points and the S axis is defined as f2(s), provided that γ is f1(s)/f2(s); recording a vertical coordinate horizontal load peak point F on a curve of the F-S functionmaxThe corresponding horizontal deformation value of the abscissa is S1Set point { A1，A2，……，Ai，……，AnIs a point on the F-S curve, n > i, with the abscissa {1/n, 2/n, … …, i/n, … …, n/n }. times.S1Calculate point { A1，A2，……，Ai，……，AnThe gamma values of { gamma } are respectively1，γ2，……，γi，……，γnIf { gamma }, ifi，……，γnAll < theta, and gammai-1Is not less than theta, then Ai-1The ordinate of the point is Fk(ii) a Wherein n is more than or equal to 50, and the value range of the parameter theta is more than or equal to 0.96 and less than or equal to 0.98;
the parameter θ is set to avoid the fluctuation region on the F-S function curve, where θ is 0.97 and n is 100 in this embodiment. F-S function curve of model 1, calculated, { γ21，……，γ100Maximum value of 0.969 < 0.97, gamma20When the ratio is 0.973 to 0.97, A is added20The point is taken as the maximum linear horizontal bearing capacity performance point of the masonry column 1; the origins O and A are20Extension line of point connecting line and horizontal bearing capacity extreme point M1Horizontal line of (B) intersects with1Point and then go through B1The point makes a perpendicular line to the abscissa axis and intersects with the F-S function curve at Y1Stippling Y with1The point is taken as the horizontal bearing capacity yield point of the masonry column 1; horizontal bearing capacity extreme point M1As a point of failure of the masonry column 1.
F-S function curve of model 2, calculated, { γ26，……，γ100Maximum value of 0.967 < 0.97, gamma25When the ratio is 0.971 to 0.97, A is added25The point is taken as the maximum linear horizontal bearing capacity performance point of the masonry column 1; the origins O and A are24Extension line of point connecting line and horizontal bearing capacity extreme point M2Horizontal line of (B) intersects with2Point and then go through B2The point makes a perpendicular line to the abscissa axis and intersects with the F-S function curve at Y2Stippling Y with2The point is taken as the horizontal bearing capacity yield point of the masonry column 1; horizontal bearing capacity extreme point M2As a point of failure of the masonry column 1.
F-S function curve of model 3, calculated, { γ29，……，γ100Maximum value of 0.968 < 0.97, gamma28When the ratio is 0.972 ≥ 0.97, A28The point is taken as the maximum linear horizontal bearing capacity performance point of the masonry column 1; the origins O and A are28Extension line of point connecting line and horizontal bearing capacity extreme point M3Horizontal line of (B) intersects with3Point and then go through B3The point makes a perpendicular line to the abscissa axis and intersects with the F-S function curve at Y3Stippling Y with3The point is taken as the horizontal bearing capacity yield point of the masonry column 1; horizontal bearing capacity extreme point M3As a point of failure of the masonry column 1.
F-S function curve of model 4, calculated, { γ35，……，γ100Maximum value of 0.969 < 0.97, gamma34When the ratio is 0.971 to 0.97, A is added34The point is taken as the maximum linear horizontal bearing capacity performance point of the masonry column 1; the origins O and A are34Extension line of point connecting line and horizontal bearing capacity extreme point M4Horizontal line of (B) intersects with4Point and then go through B4The point makes a perpendicular line to the abscissa axis and intersects with the F-S function curve at Y4Stippling Y with4The point is taken as the horizontal bearing capacity yield point of the masonry column 1; horizontal bearing capacity extreme point M4As a point of failure of the masonry column 1.
In this embodiment, the maximum linear horizontal bearing capacity { F) of the masonry column 1 in the model with 4 prestress values applied by the guy cable 5k1＝4.12KN，Fk2＝6.41KN，Fk3＝10.32KN，Fk412.91KN, yield level bearing force { F }y1＝6.68KN，Fy2＝9.28KN，Fy3＝12.59KN，Fy415.91KN, yield level deformation value { S }y1＝9.47mm，Sy2＝8.42mm，Sy3＝7.17mm，Sy45.72mm, ultimate horizontal bearing force { F }u1＝9.51KN，Fu2＝12.47KN，Fu3＝16.5KN，Fu419.74KN and an ultimate horizontal deformation value Su1＝20.25mm，Su2＝16.32mm，Su3＝13.96mm，Su4＝10.92mm}。
After three performance points are obtained, whether the cross-sectional area of the inhaul cable 5 reaches the standard is checked, and the standard is as follows: horizontal load F ═ FkIn the meantime, the tensile stress borne by the cable 5 does not exceed the tensile strength σ of the cable 5u0.4 times of (1), horizontal load F ═ FyIn the meantime, the tensile stress borne by the cable 5 does not exceed the tensile strength σ of the cable 5u0.6 times of (d), and the horizontal load F ═ FuIn the meantime, the tensile stress borne by the cable 5 does not exceed the tensile strength σ of the cable 5u0.8 times of the total weight of the powder.
TABLE 2 tensile stress (MPa) to which the cable 5 is subjected at three performance points
The tensile stress that the cable 5 in the 4 analytical models endures at three performance points is shown in table 2, and it can be seen that it satisfies the following requirements: firstly, at the maximum linear horizontal bearing capacity performance point, the tensile stress sigma borne by the inhaul cable 5 is 0<σ≤0.4σu＝668MPa，σuThe limit value of the tensile strength of the stay cable 5 is 1670 MPa; ② at the yield point of the horizontal bearing capacity, the tensile stress sigma born by the inhaul cable 5 should be 0<σ≤0.6σu1002 MPa; ③ the tensile stress sigma borne by the guy 5 at the point of failure should be 0<σ≤0.8σu＝1336MPa。
And step five, selecting 1952Taft Lincoln School earthquake acceleration time course according to 4 analysis models established in the step one and the step two and according to the earthquake fortification intensity of 8 degrees and 0.2g, and applying a horizontal earthquake acceleration time course to the bottom surface of the masonry column 1 along the span direction of the upper wood roof structure to perform time course analysis as shown in fig. 4. The 1952Taft Lincoln School seismic acceleration time course peak is adjusted to the following value: firstly, the time-course acceleration peak value of earthquake time-course under the action of multiple earthquakes is 70cm/s2(ii) a ② the earthquake time-course acceleration peak value of 200cm/s for fortifying earthquake action2(ii) a Thirdly, the acceleration peak value of the earthquake time course under the action of rare earthquake is 400cm/s2. The ratio of the acceleration peak value of the non-peak point acceleration to the acceleration peak value of the original 1952Taft Lincoln School earthquake time course is set according to the three conditionsAnd adjusting in the same proportion. The analysis is solved by adopting a Newton-Raphson nonlinear iteration method, the geometric nonlinear influence of a structural system is taken into account, and the building block adopts a plain concrete Drucker-Prager elastoplastic model.
In the embodiment, the maximum shearing force { V } of the masonry column 1 in the 4 analysis models under the action of the multi-earthquakek1＝5.62KN，Vk2＝6.24KN，Vk3＝6.85KN，Vk47.42KN, the ratio of the maximum horizontal deflection to the height H of the masonry column 1, { Δ k }1/H＝1/535，Δk2/H＝1/656，Δk3/H＝1/708，Δk 41/741, and the ratio of the maximum horizontal deformation to the height H of the masonry column 1 under the action of a fortification earthquake (delta y)1/H＝1/253，Δy2/H＝1/318，Δy3/H＝1/365，Δy 41/402, and the ratio of the maximum horizontal deformation to the height H of the masonry column 1 under the action of rare earthquakes { delta u }1/H＝1/193，Δu2/H＝1/263，Δu3/H＝1/301，Δu4/H＝1/353}，H＝4.08m。
And step six, judging from the aspects of the safety degree of the horizontal bearing capacity and the ductility control of the horizontal deformation according to the calculation results of the step four and the step five, and selecting a model meeting the index control requirement from m analysis models applying different prestress values to the stay rope 5:
{Fu1/Fy1＝1.42，Fu2/Fy2＝1.34，Fu3/Fy3＝1.31，Fu4/Fy4＝1.24}
{Su1/Sy1＝2.14，Su2/Sy2＝1.94，Su3/Sy3＝1.95，Su4/Sy4＝1.91}
{Fk1/Vk1＝0.73，Fk2/Vk2＝1.03，Fk3/Vk3＝1.51，Fk4/Vk4＝1.74}
{Δk1/H＝1/535，Δk2/H＝1/656，Δk3/H＝1/708，Δk4/H＝1/741}
{Δy1/H＝1/253，Δy2/H＝1/318，y3/H＝1/365，Δy4/H＝1/402}
{Δu1/H＝1/193，Δu2/H＝1/263，Δu3/H＝1/301，Δu4/H＝1/353}
with Fum/Fym≥1.3，Sum/SymMore than or equal to 1.5 is used as a control target, and the model m1、m2、m3The masonry column 1 with the prestress value of 20KN, 40KN and 60KN applied by the middle guy cable 5 meets the control target requirement, and the model m4Does not meet the requirements. Decision model m1、m2、m3The prestress value applied by the middle guy 5 is reasonably selected from 20KN, 40KN and 60KN, and the model m4The prestress value applied to the middle inhaul cable 5 is unreasonable to 80 KN.
With Fkm/Vkm≥1.0，Δkm/H≤1/500，Δym/H≤1/300，ΔumModel m with/H not more than 1/200 as control target2、m3、m4The masonry column 1 with the prestress value of the middle guy 5 of 40KN, 60KN and 80KN meets the control target requirement, and the model m1Does not meet the requirements. Decision model m2、m3、m4The prestress value applied by the middle guy 5 is reasonably 40KN, 60KN and 80KN, and the model m1The prestress value applied by the middle pull rope 5 is unreasonable to be 20 KN.
Step seven, according to the result of the step six, the reasonable range of the prestress value applied to the inhaul cable 5 is 40-60 KN. In addition, the friction coefficient between the U-shaped backing plate 3 and the cross beam 2 can make the U-shaped backing plate 3 not skid in use most of the time, but if the upper surface of the cross beam 2 is very smooth, the U-shaped backing plate 3 still has the possibility of skidding, and the friction coefficient between the U-shaped backing plate 3 and the cross beam 2 needs to be verified through the displacement condition of the U-shaped backing plate 3, taking the embodiment as an example, the method is as follows:
relative displacement between the U-shaped base plate 3 and the cross beam 2 in the fourth step is recorded, and the relative displacement between the U-shaped base plate 3 and the cross beam 2 in the 4 models is shown in the table 3 at three performance points:
TABLE 3 relative displacement (mm) between U-shaped backing plate 3 and beam 2
The relative displacement between the U-shaped base plate 3 and the cross beam 2 meets the following requirements: at the performance point of the maximum linear horizontal bearing capacity, the U-shaped base plate 3 and the cross beam 2 can not generate relative displacement; at the yield point of the horizontal bearing capacity, the relative displacement U between the U-shaped base plate 3 and the cross beam 2 is less than or equal to 5 mm; and thirdly, at the damage point, the relative displacement U between the U-shaped base plate 3 and the cross beam 2 is less than or equal to 10 mm.
It can be seen that the friction coefficient between the U-shaped base plate 3 and the cross beam 2 in this embodiment meets the requirement, but if not, the step one is required to be returned, the friction coefficient between the U-shaped base plate 3 and the cross beam 2 is changed (the roughness of the inner side of the U-shaped base plate 3 is also required to be synchronously increased during construction), and modeling is performed again.
The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.
Claims (10)
1. The selection method of the shockproof inhaul cable for the historic building masonry column is characterized by comprising the following steps of: the method comprises the following steps:
the method comprises the following steps: establishing an analysis model of the masonry column (1) including the inhaul cable (5);
step two: setting the cross-sectional area and the prestress of the stay cable (5) in the analysis model;
step three: applying horizontal load from zero to the top of the masonry column (1) in the analysis model until the masonry column (1) is damaged, and entering a fourth step if the compressive stress borne by the building blocks in the masonry column (1) in the horizontal load increasing process does not exceed the compressive strength of the building blocks; otherwise, returning to the step two;
step four: respectively judging whether the cross-sectional area of the stay cable (5) reaches the standard in the horizontal load increasing process according to the requirement of the construction process on the strength allowance of the stay cable (5), if so, entering the fifth step, otherwise, returning to the second step;
step five: applying a horizontal seismic acceleration time course to the bottom of the masonry column (1) in the analysis model to obtain the maximum shearing force applied to the masonry column (1) under the action of the earthquake and the ratio of the maximum horizontal deformation to the height of the masonry column (1);
step six: and D, judging whether the prestress value set in the step two reaches the standard or not from the aspects of safety degree of horizontal bearing capacity and ductility control of horizontal deformation according to the calculation results of the step four and the step five, recording the cross sectional area and the prestress if the prestress value reaches the standard, and returning to the step two if the prestress value does not reach the standard.
2. The method for selecting the anti-vibration inhaul cable for the historic building masonry column according to claim 1, wherein the method comprises the following steps: in the first step, a three-dimensional entity discrete element analysis model of a masonry column (1) including a guy cable (5) is established, and the self weight of the masonry column (1) and the weight of an upper layer structure borne by the masonry column (1) are taken into account during modeling; the connection units between the building blocks in the established analysis model comprise bonding strength and friction parameters between the building blocks.
3. The method for selecting the anti-vibration inhaul cable for the historic building masonry column according to claim 1, wherein the method comprises the following steps: in the second step, prestress is applied to the inhaul cable (5) by adopting a method of initial strain or negative temperature application, the tensile strength of the inhaul cable (5) is changed by changing the cross section area and the elastic modulus of the inhaul cable (5), and the prestress sigma in each inhaul cable (5) is less than or equal to 0.2 sigmau，σuThe tensile strength of the inhaul cable (5); additional compressive stress value sigma generated by stay cable (5) on masonry column (1)z≤0.15Mpa。
4. The method for selecting the anti-vibration inhaul cable for the historic building masonry column according to claim 1, wherein the method comprises the following steps: in the third step, a load increment method is adopted to carry out material elastoplasticity and geometric nonlinear simulation analysis on the whole process of the masonry column (1) structure, and the geometric nonlinear influence of the structure system is taken into account in the solving process.
5. The method for selecting the anti-vibration inhaul cable for the historic building masonry column according to claim 1, wherein the method comprises the following steps: the fourth step comprises the following sub-steps:
step 4.1: drawing an F-S function curve in an analysis model by taking the horizontal deformation S of the masonry column (1) as an independent variable and the horizontal load F as a dependent variable, and obtaining the maximum value F of the horizontal load in the linear interval on the F-S function curvekHorizontal load F at the beginning of yielding of the masonry column (1)yAnd horizontal deformation amount SyHorizontal load F when the masonry column (1) is brokenuAnd horizontal deformation amount Su；
Step 4.2: respectively judging the horizontal load F = F of the inhaul cable (5) according to the requirement of the construction process on the strength allowance of the inhaul cable (5)k、F=FyAnd F = FuAnd (5) judging whether the cross-sectional area reaches the standard, if so, entering the step five, and otherwise, returning to the step two.
6. The method for selecting the anti-vibration inhaul cable for the historic building masonry column according to claim 5, wherein the method comprises the following steps: in substep 4.1, F is obtained by the following methodk、Fy、Sy、FuAnd Su：
Marking the X point as any point on the F-S function curve, the horizontal deformation value of the abscissa of the X point as S, and defining the area of a triangle formed by the connecting line of the original point O and the X, the perpendicular line passing through the X point and the S axis as F1(S) the area defined by the curve between the origin O and the X point, the perpendicular line passing through the X point and the S axis, and the S axis2(s), let γ = f1（s）/f2(s); recording a vertical coordinate horizontal load peak point F on a curve of the F-S functionmaxThe corresponding horizontal deformation value of the abscissa is S1Set point { A1，A2，……，Ai，……，AnIs a point on the F-S curve, n > i, with the abscissa {1/n, 2/n, … …, i/n, … …, n/n }. times.S1Calculate point { A1，A2，……，Ai，……，AnThe gamma values of { gamma } are respectively1，γ2，……，γi，……，γnIf { gamma }, ifi，……，γnAll < theta, and gammai-1Is not less than theta, then Ai-1The ordinate of the point is Fk(ii) a Wherein n is more than or equal to 50, and the value range of the parameter theta is more than or equal to 0.96 and less than or equal to 0.98;
taking F on the F-S functionuThe abscissa of the maximum point M is SuThe ordinate is Fu；
Connecting the origin points O and Ai-1Extending to cross the horizontal line passing through M to point B, drawing a perpendicular line to the abscissa axis to cross the F-S function curve to point Y, and determining the abscissa of point Y as SyThe ordinate is Fy；
In substep 4.2, if the horizontal load is F = FkWhen the tension is applied, the tension stress born by the stay cable (5) does not exceed the tensile strength sigma of the stay cable (5)u0.4 times of (1), horizontal load F = FyWhen the tension is applied, the tension stress born by the stay cable (5) does not exceed the tensile strength sigma of the stay cable (5)u0.6 times of (d), and horizontal load F = FuWhen the tension is applied, the tension stress born by the stay cable (5) does not exceed the tensile strength sigma of the stay cable (5)u0.8 times of; then sigma is determineduReaching standard, otherwise, judging sigmauThe standard is not reached.
7. The method for selecting the anti-vibration inhaul cable for the historic building masonry column according to claim 5, wherein the method comprises the following steps: in the fifth step, the direction of the seismic acceleration time course is arranged along the span direction of the upper-layer structure borne by the masonry column (1), and the following data are obtained according to the seismic grade:
the maximum shearing force V of the masonry column (1) under the action of a multi-earthquakekThe ratio k/H of the maximum horizontal deformation to the height H of the masonry column (1), the ratio y/H of the maximum horizontal deformation to the height H of the masonry column (1) under the action of a defense earthquake, and the ratio u/H of the maximum horizontal deformation to the height H of the masonry column (1) under the action of a rare earthquake; geometric non-line of structure system when solvingAnd (4) sexual influence.
8. The method for selecting the anti-vibration guy cable for the masonry column of the historic building according to claim 7, wherein the method comprises the following steps: in step six, if Fu/Fy≥1.3，Su/Sy≥1.5，Fk/VkWhen the current stress value is not less than 1.0, Δ k/H is not more than 1/500, Δ y/H is not more than 1/300, and Δ u/H is not more than 1/200, the prestress value is judged to reach the standard, otherwise, the prestress value is judged not to reach the standard.
9. The method for selecting the anti-vibration inhaul cable for the historic building masonry column according to claim 1, wherein the method comprises the following steps: the selection method further comprises the following steps:
step seven: and repeating the second step to the sixth step to obtain a plurality of groups of up-to-standard prestress values, and determining the value range of the up-to-standard prestress values.
10. Shockproof cable system for the reinforcement of taking precautions against earthquakes of masonry post (1) in the ancient building, masonry post (1) is roof beam column, its characterized in that: the shockproof inhaul cable system comprises a U-shaped base plate (3) with a downward opening clamped on a cross beam (2) above the masonry column (1), and inhaul cables (5) with middle parts hung on the upper surface of the U-shaped base plate (3) and two ends anchored on a fixed foundation;
the inhaul cable (5) is connected with the U-shaped base plate (3) through the fastener (4), is in sliding connection with the U-shaped base plate (3) when the fastener (4) is loosened, and is fixedly connected with the U-shaped base plate (3) when the fastener (4) is locked;
the cross-sectional area of the stay (5) and the pre-stress to be loaded are selected using the selection method according to any one of claims 1 to 9.
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| CN105155866A (en) * | 2015-09-21 | 2015-12-16 | 华东交通大学 | Separable sheath floor-adding structure of masonry buildings and floor-adding method thereof |
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| JP2002213085A (en) * | 2001-01-23 | 2002-07-31 | Oriental Construction Co Ltd | Reinforcing structure for existing building |
| US20050028477A1 (en) * | 2003-07-28 | 2005-02-10 | Freyssinet International (Stup) | Method for strengthening a structure and associated anchorage unit |
| CN1760486A (en) * | 2004-10-15 | 2006-04-19 | 罗进南 | Slot opening building blocks or bricks as well as light shear wall and related building, and construction method |
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