考虑多维地震作用的高耸钢筋混凝土烟囱结构易损性分析

竖向地震作用对高耸烟囱结构动力响应有不可忽略的影响。选用240m高的某钢筋混凝土烟囱作为研究对象，考虑结构损伤，通过有限元软件ABAQUS，采用复合壳单元建立相应的非线性有限元分析模型。为考虑地震动的不确定性，根据谱相容性原则，选择20条合理地震动记录，进行增量动力分析。输入的地震动分别为一维、二维、三维。分别以材料应变和地面峰值加速度作为结构地震需求参数和地震动强度参数，结合增量动力分析获得的结构地震响应，采用能力需求比模型的曲线拟合法计算易损性曲线。通过钢筋和混凝土的材料应变定义四个损伤状态限值，最终得到在不同维数地震动输入时高耸钢筋混凝土烟囱结构的地震易损性曲线和倒塌概率曲线。研究结果表明，考虑多维地震作用比只考虑一维地震作用时高耸烟囱的结构易损性和倒塌概率增大。

Seismic fragility analysis for high-rise RC chimney considering multi-dimensional seismic actions

 The effect of vertical seismic actions on the dynamic responses of high-rise chimney structure cannot be ignored. A 240m-height RC chimney is studied and the damage caused by environmental factors is considered. Composite shell element is adopted to establish the three-dimensional structural nonlinear analytical model by the finite element software ABAQUS. In order to perform the incremental dynamic analysis considering the uncertainty of the ground motions, 20 ground motion records are selected based on the matched-spectrum principle. The one-dimensional, two-dimensional and three-dimensional base excitation ground motion records are used in the analysis, respectively. The peak ground acceleration and maximum strain are selected as the intensity measure and engineering demand parameters. Based on the material strain of concrete and rebar, the limit values of four damage states are defined. Combined with the responses of structures obtained by incremental dynamic analysis, the vulnerability curve is calculated with the curve fitting method. Then the seismic fragility and collapse probability curves of high-rise RC chimney structures under different seismic wave inputs are obtained. The results show that the probability of the vulnerability and collapse of the high-rise chimneys considering the multi-dimensional seismic actions is larger than that just considering one-dimensional seismic actions.