Study On Damage Based Seismic Design Of RC Structure

Great economic losses and casualties have been caused by strong earthquakes in the past decades,and the Wenchuan earthake which happened on May 12th 2008 incurred substantial damages in China,which proclaims that high-level seismic design is crucial.Vast researches and survey data indicate that certain measures could effectively strengthen the earthquake resistance capacity of structures, which leads to the safety of people and their properties.Therefore,the study on damage mechanism and failure process of structures under strong earthquakes, as well as anti-seismic measures is of great significance to human beings.The obvious double-epicenter made the Wenchuan earthquake ground motion distinctive,that hasn't been considered in the present Chinese seismic design code,which needs verification.An appropriate damage model used for evaluation of the progress of structural damage should take both the damage correspond to dissipated energy and displacement overpass into consideration.Four present performance-based seimic design methods were described,and then focused on damage-based design method,various damage models were described, including member based damage models and structure based ones.Concise introduction of theories and techniques of nonlinear seismic response analysis of RC structures was presented in conjuction with the finite element analysis program CANNY,and comparisons of the selected damage models were made in 3D nonlinear dynamic analysis of a 9-storey RC structure subjected to a real Wenchuan earthquake excitation.The results show that damage in the structural members increased mainly in the first shock.Further spectral analysis on Wolong earthquake wave indicates that the difference between the first and second shock is obvious,although the GPA of the second shock is quite large,it's frequency which is much higher than the fundamental frequency of the structure results in only slight damage to the structure.It is suggested that the spectral characterics of the earthquake wave shuld be considered seriously in seismic design. A damage-based approach based on target damage index has been proposed and verified in conjunction with present seismic design method for high intensity earthquake.Finally,parametrical sensitivity analysis was taken out,the results show that the relationship between the demand ductility factor and other parameters is reasonable,and the value of ductility factor is also in a reasonable range.