Study On Seismic Performances Of Composite Steel Plates Shear Wall Structure With High Strength Concrete

Shear walls as important lateral-force-resisting and load-bearing elements of ultra high-rise buildings always bear the larger bending moments,shear forces and axial forces.While China is an earthquake-prone country,in order to ensure the ductility of shear wall components under seismic motions,concrete strength grades of shear wall are required to be no higher than C60 according to China Codes and strict restriction for axial compression ratio of shear walls are also made.However,with the increase of structure height,to meet the requirements of specification,shear walls at the bottom of the structure tend to be designed as very larger cross sections with higher reinforcement ratio,which lead to more difficult construction,reduce of available area,less economic benefit etc.To solve these problems,by adopting advantages of high performance concrete and composite structures,composite steel plate shear wall with C80 high strength concrete(HSC)were developed and tested.Results show that good ductility,high rigidity and bearing capacity can be found to meet the engineering requirements.But still problems remain:(1)How to simulate the behaviors of the composite shear wall in an overall structure?(2)What on earth the actual performances of the composite shear wall are under external excitations?(3)How to evaluate the damage of the composite shear wall after an earthquake? Therefore,in the paper based on previous experiments,a finite element model method is set up to accurately simulate performances of C80 HSC steel plate shear wall in the overall structure by adopting Perform–3D software.Then a existing frame-core shear wall high-rise building was selected,according to the different requirements of Seismic Performance design,parts of original reinforced concrete shear walls were replaced by HSC steel plate shear walls,and seismic performances of those two structures were compared under earthquake excitations.Finally,a performance evaluation system for HSC composite shear wall was proposed to set the performance standard and damage level.The main researches and conclusions are as follow:(1)Previous research results have proved that C80 HSC steel composite shear wall is of good ductility,high rigidity and bearing capacity and can meet the requirements of engineering application.But the precise modeling method of shear wall components does not apply to the whole structure analysis.So on the basis of experiments,a macroscopic finite element model was established by using PERFORM-3d software,comparisons between experimental results and analysis draw following conclusions: under low cyclic loading,initial stiffness and ultimate shear capacity from simulation results are accurate enough compared to experimental results,with a 5% deviation maximumly.Finite element calculation result reasonably reflect the stress process and damage state of the shear wall specimens,which verified that the simulation method is suitable for global inelastic analysis in HSC steel plate shear wall structures.(2)To study the difference of seismic performances between HSC steel plate concrete shear wall structure and ordinary reinforced concrete shear wall structure,a existing frame-core shear wall high-rise building was selected,composite shear walls were arranged based on Seismic Performance Design Method.Through comparing analysis of macro parameters and shear wall material damage situations of the two kinds of structure under ground motions,following conclusions can be drawn: compared with original structure,structural overall performances are not changed significantly by adopting HSC steel plate shear walls,only floor stiffness increase slightly at bottom stories.As for shear wall material damage,concentrated serious damage can be found at the strengthened bottom stories in original structure;while only minor damage can be found in HSC composite shear walls.Therefore,HSC steel plate shear walls with thinner thickness can meet the requirements of seismic performance,providing possibility of higher-performance and economic core tube shear walls.(3)To reasonably evaluate the damage of HSC composite shear wall after an earthquake,based on crack control,change of carrying capacity and the lateral drift angle limit,a criteria of performance division and damage index limits corresponding to different performance levels was proposed.According to the damage model proposed in this paper,3 specimens from other literatures were selected to calculate damage index and damage extents,computed results agree with real experimental phenomenon well.The rationality of the performance evaluation system is verified.Finally using the evaluation system to assess the performances of HSC composite shear walls in structure.Calculated damage extents corresponding to damage index is basically consistent with material strain based damage assessment,which verifies the rationality of the evaluation system proposed in this paper to be applied in structures.