Experimental Study On Seismic Behavior Of Reinforced Line-shaped Shear Wall Strengthened By Enlarging Section Method

The method of enlarging sectionisa common and effective method to reinforce reinforced concrete structure which is often applied in shear wall structure reinforcement engineering and includes unilateral enlarged section method and double enlarged section method.Because these two reinforcement methods are different in force transmission and stress characters,the seismic performance of reinforced shear wall will be affected.However,it is not clear that the specific differences in the failure mode,hysteretic characteristics,bearing capacity,ductility,stiffness and energy dissipation capacity.Thus,studies on seismic behavior of shear wall strengthened by single and double section enlarging section method and explorations on the reinforcement effect can complete research of seismic strengthening of shear wall in China.Based on the existing research results and norms,we designed unreinforced shear wall,reinforced concrete shear wall with double side enlarged section and shear wall with 3 sides of reinforced shear wall,of which the axial compression ratio,shear span ratio and reinforcement ratio of the specimens are the same.We studied the seismic performance of the three by pseudo static test and analyzed the reinforcement effect of reinforced concrete shear wall with single and double cross section.Experimental results show:(1)the hysteretic characteristics,bearing capacity,ductility,stiffness,energy dissipation capacity and seismic performance of reinforced concrete shear wall specimens with increasing section method are all improved significantly compared with that of the unreinforced shear wall specimens.Besides the reinforcement effect is remarkable,and the reinforcement method of single and double side enlargement can be effectively used in the seismic strengthening of shear walls.(2)The seismic behavior of reinforced concrete shear wall of both double side and single side enlarged section is different.Specific ratios are as follows,the initial stiffness is approximately the same,the ratio of ultimate bearing capacity is 1.26,and the failure load ratio is 1.21.Peak to peak displacement ratio is 1.04,the ultimate displacement ratio is 1.01,the ultimate displacement ratio is 1.01,and the equivalent viscous damping coefficient is 1.09.We can find that it's better using the strengthening method of double side enlarged sectionthan using the one side enlargement section method in the seismic strengthening of the shear wall.On the basis of experimental study,we adopt element analysis software ABAQUS to simulate the whole process of reversed cyclic loading of the three pieces of Line-shaped shear wall model and finally got the failure mode,stress distribution,hysteretic behavior and ultimate bearing capacity of wall.Compared these results with the experimental results,we proved that the finite element model and the analysis process are reasonable and reliable.Then,we carried the finite element analysis of reinforced concrete shear wall specimens with different thickness of 3 sections of single side enlarged section.Finally,we did a research on the effect of different thickness of reinforcement section on the seismic behavior of shear wall strengthened with single side enlarged section.The study showed:(1)The morphological characteristics of the simulation results are in agreement with the experimental results,and the ultimate bearing capacity error is less than 10%.The finite element analysis results is basically coincided with the experimental results.It is proved that the finite element model and the analysis process are reasonable and reliable,which has high accuracy at the same time.(2)Along with the enlargement of the thickness of reinforcement section,the bearing capacity and ductility of reinforced concrete Line-shaped shear wall specimens with one side enlargement section show a rising trend,of which the growth rate is gradually decreasing.And the seismic retrofit effects of the reinforced concrete Line-shaped shear wall specimens with single section enlarged section of 85 mm and the double side reinforced specimen with 70 mm are basically similar.In conclusion,the enlargement method of section reinforcement can significantly improve the seismic performance of Line-shaped shear wall and also an effective way for seismic strengthening of shear walls.However,the seismic retrofit effect of double side enlargement section method is better than that of single side enlargement section method.And by enlarging the thickness of the reinforcement section,we can make the seismic performance of reinforced concrete shear wall strengthened with single side enlarged section develop the same effect.Through the preliminary research on seismic behavior of reinforced concrete shear wall strengthened by enlarging section method,this study can provide reference for the reasonable reinforcement of the actual shear wall structure.At the same time,this study can help exploring the seismic behavior of shear wall strengthened by enlarging section method further.More,it can help layingthe theoretical foundation of optimizing reinforcement method of increasing section of shear wall,and really has important research value.