Comparative Study On The Story Drift Limits Of Reinforced Concrete Structure In Chinese And American Seismic Design Codes

Many scholars have pointed out that Chinese code is too strict on the elastic story drift limits of RC structures under earthquakes,resulting in an increase in the amount of building materials,stiffness of structures and seismic response of structures,which causes adverse effects on structures.Therefore,it is necessary to conduct an in-depth study on the rationality of the limit of elastic story drift of RC structures under earthquakes.Through the calculation of the structure models,the comparative study on the story drift limits of RC structures under earthquakes between Chinese and American seismic codes are conducted in this paper.Based on the comparison result,suggestions of limits of elastic story drift of RC structures under earthquakes in Chinese code are given.The main achievements of this paper are as follows:(1)Establish a comparative relationship of the story drift limits of RC structures between Chinese and American seismic codes.Define the richness ratio ? of the story drift limits between Chinese and American codes.Based on the premise that the structure is slightly nonlinear under the fortification earthquake once in 475 years,the comparison of limits of story drift between Chinese fortification earthquake and American design earthquake is translated into Chinese minor earthquake and American design earthquake.Comparing principle is proposed in order to reflect the difference in the story drift limits between two countries.(2)Contrast and unify seismic codes of two countries from several aspects.Namely site classification,seismic design response spectrum,seismic zonation,importance category,value of gravity loads,elastic modulus of materials and various adjustment parameters that affect the displacement calculation results.The complete process of story drift in Chinese and American seismic codes is sort out.(3)40 models of four types of RC structural systems(frames,shear wall,frame-shear wall,frame-core tube)are established with different fortification intensity and different heights recording to Chinese code under site category III.Calculations of ? are performed by using Etabs,analysis on effects on ? of fortification intensity,structural height and site classification is also conducted;Based on the comparison result,suggestions of limits of elastic story drift of RC structures under earthquakes in Chinese code are given.(4)Four RC shear wall structure models were designed based on the proposed limits of elastic story drift.Elasto-plastic calculation of the four models is conducted by using Performed-3D;based on the research of deformation limits of components,the paper evaluates the safety performance of the four models under severe earthquake by using the “First vertical component failure criterion”,verifying that it is reasonable to modify the elastic story drift limit of RC shear wall structure to 1/550.