Study On The Seismic Analysis Method Of Structure Considering Strain Rate Effect

Most materials used in civil engineering are sensitive to strain rate, which should be considered in seismic analysis. But at present, there is lack of method for considering strain rate effect. Using theoretical analysis and numerical simulation, progressive collapse analysis method, influences of strain rate on the nonlinear response of RC frame structure and transmission tower-line system, the methods for considering strain rate effect in pushover analysis and nonlinear time history analysis, influences of strain rate on the progressive collapse of RC frame structure and transmission tower-line system are studied. The primary contents are listed as follows:(1) The method that the mass of the elements is still retained rather than removal after elements lose the load-bearing capacity is proposed. According to the "code for design of concrete structures"(GB50010-2010), the user subroutine VUMAT that can be implemented in the advanced finite element program ABAQUS is coded. The simulated results of a RC column under static and dynamic loading modes are consistent with experimental results.(2) Incremental dynamic analysis of a four-storey RC frame structure is conducted to study the effects of strain rate on the maximum top displacement, maximum base shear, maximum storey drift, capacity curve of the structure. Incremental dynamic analysis of a transmission tower-line system is conducted to study the effects of strain rate on the nonlinear responses of tower and line.(3) Based on the basic dynamic theory of structure, pushover analysis methods considering strain rate effect are proposed. The process of pushover analysis can be treated as a1/4cycle, the analysis time takes a quarter of the period of the equivalent linear single degree freedom system. Two methods are proposed. Incremental dynamic analysis and pushover analysis of two structures are conducted, the results indicate the reliability of the proposed methods.(4) A simplified and practical method considering strain rate effect in nonlinear time history analysis is proposed. First, perform nonlinear time-history analysis without considering strain rate effect. Then the model can be modified according to estimated strain rate. Finally, perform nonlinear time-history analysis again. The effectiveness of the proposed method is proved by three numerical examples.(5) By using the coded program, the strain rate effects on the collapse-resistent capacity and collapse process of RC frame structure and transmission tower-line system are studied.