Performance Evaluation And Analysis Of Seismic Capacity Of ECC Shear Wall Under Rare Earthquake

The traditional seismic design of reinforced concrete shear wall is to guide the destruction at the bottom of the shear wall.The existing seismic damage shows that the cross section at the bottom of the wall will have severe flexural failure and the ductility of the common concrete material is poor.Thus,there will be a lot of residual deformation after the earthquake.It goes against structural reinforcement and repair.Therefore,improving the deformation capacity of the bottom area of shear wall is the key to improve the seismic performance of the whole structure.Fiber reinforced cement composite(Engineered Cementitious Composite,referred to as ECC)with greater capacity of compressive strain,good tensile strain hardening and shear performance,which will be applied at the bottom of the shear wall to improve the ductility and deformation capacity of shear wall.At present,the study about ECC shear wall only based on single wall component experimental research,there are not performance analysis of the whole structure.consequently,it is necessary to investigate the actual seismic performance and the effect on the seismic capacity in the upper storeys of the ECC shear wall structure.In this paper,34 fully plastic numerical models are designed in view of the different ECC height,structural system,the unitary factor of the double limb wall,the stiffness ratio of the frame shear wall and the spatial arrangement of the shear wall.Comparing the failure mode,structural deformation and energy dissipation of shear wall between ECC shear wall and common RC shear wall under rare earthquake.and the overall performance of ECC shear wall is evaluated.After the elastic-plastic time history analysis for 34 models upon preset failure mode.Counting the distribution of ECC shear wall seismic capacity requirements along the floor,calculating the moment and shear amplification coefficient on each floor in different structure.and summarizing the variation of amplification coefficient along the floor.The main conclusions are as follows:(1)When the bottom of the shear wall is replaced with ECC material,the energy dissipation capacity of the shear wall can be improved significantly.With the increase of the height of using ECC material,the energy consumption of shear wall increases.(2)Because of the toughening effect of high strength fiber,ECC material can reduce the probability of shear cracking of ECC shear wall and reduce the shear damage.(3)After the replacement of the ECC material at the bottom of the shear wall,the probability of bending failure will increase in the adjacent upper floors.For the shear wall structures,the larger integral coefficient of the coupled shear walls,the damage of the shear walls will be more serious;for the frame-wall structures,the damage of the shear walls will become slighter with the increase of the stiffness ratio.(4)The ECC shear wall and reinforced concrete shear wall are similar on the principles of the moment magnification coefficient.The max magnification coefficient is at the middle floor and it decreases in proper order up and down along the floor.It is the ECC wall structure that the moment magnification coefficient is bigger than the reinforced concrete structure adjacent to the 5 ~ 6 upper floor.The moment magnification coefficient at the ECC structure is approximately equal to the reinforced concrete structure in the upper wall.(5)As for shear wall structure,It is the ECC shear wall that the shear magnification coefficient is bigger than the reinforced concrete structure adjacent to the 4~5 upper floors.And for frame shear wall structure,the shear magnification coefficient in ECC shear wall is bigger than the RC wall adjacent to the 8~9 upper floors.In the upper storeys,the shear magnification coefficient curve of the ECC shear wall and the ordinary RC shear wall is basically coincident.(6)Different structural systems have different bending moment magnification coefficient,the double shear wall has the largest coefficient while the symmetric frame shear wall structure's is the smallest,and the asymmetric frame shear wall structure between above the two.The bending moment magnification coefficient grows with the increase of the integral coefficient of shear wall structure,generally,the higher structural height means the larger coefficient.This coefficient of frame shear wall structure increases with the increase of the structural stiffness characteristic value.