Seismic Performance Analysis Of RC Frames Based On A Modified I-K Restoring Focre Model Of Plastic Hinges

The earthquake disaster is one of the biggest threats to humanity. Earthquakes cancause great number of casualties and loss of social property due to the collapse of manybuildings under strong motions. The deterioration of strength and stiffness of structuralmembers is the main reason of structural collapses under strong earthquakes. Therefore,it is one key contents of Performance-Based Earthquake Engineering (PBEE) to studythe seismic behavior of engineering structures considering the deterioration of strengthand stiffness of structural components. Recently, a modified Ibarra-Krawinkler (I-K)model has been proposed for steel structures to simulate deterioration of structuralcomponents. However, this model has been used much less for reinforced concrete (RC)structures. In this thesis, based on the OpenSees platform, the modified I-K model isused to carry out the seismic performance analysis of RC components,2-D and3-D RCframe structures.The main contents of this thesis are as follows:1. The main research progress on seismic analysis methods of RC frame structuresand the hysteretic models considering the deterioration of stiffness and strength areintroduced respectively. The fundamental theory of nonlinear analysis is brieflysummarized, and the characteristics of three kinds of nonlinear analysis models and twokinds of hysteretic models and structural seismic analysis models are discussed. Then,the finite element software OpenSees is introduced. A cantilever column is simulated forquasi-static analysis, and a2-D RC frame is simulated by static pushover analysis andtime history analysis under ground motions using the OpenSees software.2. The backbone curve and hysteretic rules of the modified Ibarra-Krawinkler (I-K)model are introduced, and four kinds of deterioration modes, i.e., the basic strengthdeterioration, the post-capping strength deterioration, the unloading stiffnessdeterioration, and the accelerated reloading stiffness deterioration, of the modified I-Kmodel are discussed. In order to evaluate the results of deterioration of RC components,a RC cantilever column is simulated for quasi-static analysis with the modified I-Kmodel rules using software MATLAB and OpenSees, respectively.3. Based on the RC component tests of PEER database, the parameters ofbackbone curve and hysteretic curve of the modified I-K model are calibrated usinggenetaic algorithms, and several empirical formulas of parameters are developed bystatistical regressions. It is shown by the comparison of finite element analysis with theexperimental results that, the calibrated parameters can better model the mechanical properties of RC components, and meanwhile, they can better simulate the deteriorationof structural components under cyclic loadings.4. In order to study seismic behavior of2-D and3-D RC frame structures underseismic excitations, the fined numerical simulations of RC2-D and3-D frame structuresare carried out based on the modified I-K models using OpenSees. The numericalsimulation results are compared with the results of experiments. It has been shown bythe comparions that the modified I-K model can better simulate the deterioration ofstructural components under earthquake actions.