Seismic fragility analysis for high-rise reinforced concrete chimney
ZHOU Changdong;ZENG Xulang;ZHAO Feng;ZHOU Hao;School of Civil Engineering,Beijing Jiaotong University;MCC Central Research Institute of Building and Construction,Co.Ltd;
To analyze the seismic behavior of high-rise RC chimney,this paper selected one 240 high RC chimney as the research object. On the basis of distributed plastic fiber beam-column element,a detailed three-dimensional structural nonlinear analytical model is developed using the finite element software Open Sees. In order to consider the uncertainties in ground-motion realizations,according to the principle of spectral compatibility,21 natural ground motion records are selected as the basis of incremental dynamic analysis. The peak ground acceleration and curvature ductility ratio have been selected as the intensity measure and structural seismic demand parameters,respectively. Based on lognormal assumptions,nonlinear incremental dynamic analysis is then performed for the case study RC chimney and statistically analyzed to build the probabilistic model of the seismic demand. According to concrete and longitudinal reinforcement strain levels,four damage limit states,named as the light,moderate,extensive and complete damage,were defined in terms of the analysis results of 95 sections. Then the fragility curves are developed for the RC chimney at various damage states and its vulnerability assessment and analysis are conducted. The study indicates that for frequent earthquake,basic earthquake and rare earthquake,the probabilities of exceeding the light damage state are around 0%,20% and 75%,respectively; while the probabilities ofexceedance corresponding to moderate,extensive and complete damage states are approximately zero. The results of the fragility analysis developed in this paper for the RC chimney would be helpful for seismic design,seismic risk assessment and seismic retrofit of RC chimney structures.