Structural Damage Assessment And Seismic Design Based On Three-dimentional Nonlinear Seismic Response Analysis

Many investigations of earthquake disasters indicate that beams and columns of R/C structure which is the most popular structure form will go into nonlinear state with different level under strong motion earthquake, and the nonlinear response will cause some damage and even collapse to the R/C structure. For the above reasons, it is very necessary to proceed three-dimentional nonlinear seismic response analysis and structural damage assessement to R/C structure because they are the base to help us to understand the nonlinear response charactor of the R/C structure, and also the base to evaluate the seismic damage quantitatively and finally establish a damage performance-based seismic design method.With the program CANNY, we establish precise three-dimentional member structure model, and define the nonlinear character of the nonlinear spring in the analytic model of beams and columns which reflect the members' nonlinear character, then choose proper damping and earthquake waves which have been modified, at last using the normal calculating methods Wilson-θ or Newmark β we can calculate the nonlinear response of the R/C structure under strong motion earthquake. The application is a 9-story R/C frame structure, and there is a detailed discussion on the effect of P-△ , damping ratio and the difference of three-dimentional and two-dimentional model mode. The above discussion can not only guide the seismic design of the structure but also be useful for the succeeding seismic damage assessment.There are many damage assessment models of the R/C structure now, but the most properiate form is the model which considers both the damage caused by dissipated energy and that caused by displacement overpass. After analyzing some classical two-parameter model, the paper gives an improved two-parameter model modified from the Statish two-parameter model. The major improvement is defining the damage boundary as kδy, which considers the effect of the earthquake process more roundly. Base on the results of the nonlinear response analysis of the R/C structure, the paper calculat the damage indexes of the structural members using the classical damage assessment model and the improved model, and also give a comparison between the above damage assessment results which approve therationality of the improved model. Then the paper gives the calculation model of damage to the whole structure. After analysing the relationship between the whole structural damage and that of the members, an contrast to the real condition of the damage is give. At last, based on the above damage assessment and analysis, the paper put forward a new performance-based seismic design based on damage assessment, which establishes the internal relations between the damage and the ratio of reinforcement. The new performance-based seismic design based on damage assessment is an important meaningful attempt to complete the performance-based seismic design method.