Analysis Of Earthquake Response And Seismic Performance Evaluation Of Existing Damage Buildings

Damage in buildings accumulates gradually because of effects of cyclic load, circumstance erosion, material aging and other deficiencies during their service life. The incremental damage decreases existing buildings' carrying capacity and thus the capacity to resist external disaster. When the earthquake occurs, they may be destroyed badly. So, the task to estimate the earthquake response and seismic performance of existing buildings becomes urgent.It is necessary to identify the actual damage of existing buildings before the task is executed. There are three levels for damage identification: material, element and structure. The stiffness matrix of shear type reinforced concrete frames are Jacobi matrix, the damage identification at structural level can be implemented easily.The shaking table tests of model structures can reappearance factually the response of buildings under specified earthquake ground motion. The results of the tests shown the different response of new buildings and existing buildings, the mechanism of energy dissipation of existing buildings at different damage status is studied.There are many theoretical methods that can be used to evaluate the seismic performance of existing buildings. The nonlinear static procedure (NSP) is one of this methods, the capacity of a structure can be determined by substituting the MDOF system with a SDOF system. On the other hand, NSP may use the capacity spectrum method (CSM) to calculate the demand by simplifying the inelastic response spectra (IRS) into equivalent linear elastic response spectra (LERS). Plot the demand diagram and capacity diagram together, the performance point that represents the maximum structural displacement expected for the demand earthquake can be obtained easily. Thus the evaluation can be performed.The study of shaking table tests and finite element analysis disclose the differences of seismic performance between new buildings and existing buildings. The pros and cons of current evaluation methods are formulated. Also the problems requiring further studies are discussed.