Study On Seismic Capacity Demands And Influencing Factors Of RC Shear Wall Based On Expected Failure Mode

Shear wall is the main lateral resistant member in high-rise building,whose mechanical performance under the earthquake has become the focus.The capacity design method proposed by T.Paulay adjusts the design internal force of structure to form the expected failure mode.Foreign researchers have made extensive research on the capacity design of RC shear wall,especially on the magnification coefficient for shear force of shear walls.However,there is little research on the magnification coefficient for seismic capacity of shear walls in China.In this thesis,the seismic capacity requirements and the influencing factors for RC shear walls are studied based on the expected failure mode.The elastic-plastic time history analysis was established for the frame-shear wall structure and shear wall structure of the zone whose seismic precautionary intensity is 8(0.2g)in China.Preliminary study on the distribution of bending moment and shear force under earthquake was investigated.Besides,the requirements for bending moment and shear force under earthquake were analyzed.And coefficient studies for bending moment magnification and the shear force magnification were conducted considering structure forms,structure height,stiffness eigenvalue of frame-shear wall structure,integral coefficient of shear wall structure,the flexural over strength factor at the wall base and ground motion intensity.This may provide a reference for magnification coefficient expression that has definite physical meaning and takes the main factors into account.This paper mainly draws the following conclusions:(1)The bending moment and shear force requirements decrease as the increase of the structural height for frame-shear wall structure and shear wall structure subjected to destructive earthquake,while there is a certain amplification effect in the middle of the structure.(2)The bending moment magnification coefficient of the shear wall firstly increases and then decreases as the structural height increases,and reaches its maximum in the middle of the structure.The shear magnification coefficient is uniformly distributed along the height and slightly increases in the middle.(3)With the increase of the stiffness eigenvalue,the shear force magnification coefficient of shear wall in the frame-shear structure increases.The bending moment magnification coefficient increases in the lower part of the structure and decreases in the upper part.With the increase of the integral coefficient,the bending moment and the shear force magnification coefficient of the shear wall in the shear wall structure increase.(4)The influence of the flexural over strength factor at the wall base on the shear wall of the frame-shear wall is greater than that of the shear wall structure.The bending and shear resistant requirements of shear wall significantly increase at the bottom with the increase of the flexural over strength factor at the wall base.The effect becomes weaker as the structure height increases.(5)The effect of ground motion intensity on the bending and shear resistant requirements of the shear wall is obvious.With the increase of the ground motion intensity,the bending moment and the shear force magnification coefficient in the bottom reinforced area of the shear wall increase greatly at first and slowly later.The magnification coefficients in the area above structure reinforcement keep increasing and the phenomenon in the central part is more obvious.(6)The contribution of the high vibration mode has a great influence on the seismic demand of the shear wall,which is mainly manifested in the increase of the demand of the central bending and shearing of the structure.The influence of the high vibration mode is more obvious when the height and the ground motion intensity are larger as well as the flexural over strength at wall base is smaller.