Finite Element Analysis And Experimental Study On Superimposed Concrete Shear Wall With Replaceable Toes

Precast superimposed concrete shear wall was introduced from Germany,and has been widely used in China in recent years since this precast shear wall has the advantages of fast construction,high industrialization and green environmental protection.However,this precast shear wall does not consider the seismic fortification in the use of Germany.Since earthquake in China are more frequent,the earthquake range is wide and the intensity is larger,the seismic behaviors of this precast shear wall must be improved and studied.With the development of seismic technology and seismic design requirements,the resilience of buildings for quick recovery of normal life is required in urban residents,so the recoverable functional structure is greatly concerned in the seismic design of precast superimposed concrete shear wall.Based on the research states of replaceable structures,and the achievements of the study group in the composite shear wall over the years,this paper proposes a novel precast superimposed concrete shear wall with replaceable toes.In the proposed structure,two left and right notches are set at the corner of the traditional precast superimposed concrete shear wall,and replaceable steel members are arranged at the notches,which are connected with the superposed wall panels through embedded bolts.In order to study the seismic performance of composite shear walls with replaceable toes,cyclic loading tests and finite element analysis are carried out in this paper.The main contents and results are as follows:(1)A new type of composite shear wall with replaceable toes and traditional precast composite shear wall are designed and manufactured,and cyclic loading tests before and after the replacement are carried out.The failure modes,lateral bearing capacity,ductility coefficient,stiffness degradation,energy dissipation ability and residual deformation are obtained.Compared with the test results of traditional composite shear wall,it was found that the failure mode of the two walls are somewhat similar.But there are cracks which have developed diagonally upward in the stress concentration part of the new type composite shear wall,and the damage concentration is within the height range of the replaceable toe members and the weakened area at the bottom of the shear wall.The bearing capacity of the new type proposed shear wall has decreased by 28.57% compared with the traditional composite shear wall,but the deformation capacity has been improved,and the energy dissipation capacity is higher than the old one before the wall toes are replaced.The residual deformation of the new type composite shear wall before the replacement is small so that the replacement of the wall toes can be completed.(2)The finite element model of the test specimens is established,and then the monotonous loading simulation is carried out.Compared with the test skeleton curve,the calculated skeleton curve has higher calculated stiffness,but the curve trend is consistent and the bearing capacity is similar.The calculated distribution of equivalent strain cloud diagram and equivalent stress cloud diagram of concrete can better reflect the failure mode of the wall,which is in good agreement with the test results.This shows that the establishment of the finite element model is more reasonable.(3)On the basis of the finite element model,the parameter analysis of the composite shear wall with replaceable toes is carried out by changing the axial compression ratio,the thickness of the corrugated steel plate,the steel grade of the steel plate,and the height of the corrugated steel plate.The calculation results show that the axial compression ratio,the thickness of the corrugated steel plate and the height of the corrugated steel plate have a significant effect on the seismic performance of the wall.As the axial compression ratio and the height of the corrugated steel plate of the replaceable wall toes increase,the peak bearing capacity and the ultimate bearing capacity of the wall increase,and the ductility decreases;while an excessively high axial compression ratio and an improper height of the corrugated steel plate are detrimental to the wall seismic resistance.The numerical simulation results show that increasing the thickness of the corrugated steel plate can improve the stiffness and bearing capacity of the wall.(4)In order to improve the failure mode of the wall and increase the bearing capacity,the thin steel plate is embedded in the bottom of the wall.the finite element analysis results show that the addition of steel plates in the non-replacement area of the test specimen can effectively improve the failure mode of the wall and enhance the initial stiffness and bearing capacity of the wall.