Mw7.8级土耳其与汶川地震作用下地铁车站结构的地震易损性分析

Seismic fragility analysis of subway station structures under the Turkey Mw7.8 and Wenchuan earthquakes

  • 摘要: 2023年2月6日土耳其发生的Mw7.8级地震造成了重大人员伤亡和经济损失,与之震级相当的Mw7.9级汶川地震也曾对我国多个地区造成不可估量的伤害和损失。为探究两次地震中地震动记录特性的差异对地铁车站结构地震响应的影响,依据震中距相似的原则各选取了12条地震动记录,从记录时程、反应谱、地震动强度指标等方面分析了地震动记录特性的差异,建立了考虑土体非线性及混凝土损伤的两层三跨地铁车站有限元模型,分析了两次地震中典型地震动记录作用下地铁车站结构的地震响应差异,并分别给出了两次地震作用下两层三跨地铁车站结构的易损性曲线。分析结果表明:土耳其Mw7.8级地震记录的主要特征是具有速度脉冲,而汶川地震的主要特征是地震动记录存在双平稳段;地铁车站结构的层间位移角与结构的累积损伤相关,速度脉冲使结构的层间位移角瞬时增大,造成较大的损伤累积,在加载等级低于0.3g时,土耳其地震记录对地铁车站结构造成轻度破坏的概率更大,在加载等级高于0.3g时,汶川地震记录中的第二平稳段会显著增大结构层间位移角峰值及残余位移,结构产生重度破坏甚至倒塌的概率更大。

     

    Abstract: The earthquake of Mw7.8 magnitude that occurred in Turkey on February 6, 2023 (TK), resulted in significant human casualties and economic losses. Similarly, the Wenchuan earthquake (WC), with a magnitude of Mw7.9, caused immeasurable damage and losses in several regions of China. To investigate the characteristic differences between these two earthquakes and their impact on the seismic response of subway station structures, this study selects 12 seismic records with similar epicentral distances from both TK and WC earthquakes. The seismic records are analyzed in terms of record time history, response spectrum, and seismic intensity indexes to examine the characteristics differences. Additionally, A finite element model of a two-story, three-span subway station considering soil nonlinearity and concrete structure damage is established. The seismic response differences of the subway station structure under typical records from both earthquakes are analyzed, and its fragility curves under TK and WC earthquakes are provided. The results indicate that: The main feature of TK earthquake is the presence of velocity pulses, while the main feature of the WC earthquake is the presence of double-plateau in the seismic records; The interstory displacement ratio (IDR) of the subway station structure is related to the accumulated damage of the structure, and the velocity pulse causes the IDR of the structure to increase instantaneously, resulting in a larger accumulation of damage. At loading levels below 0.3 g, the probability of minor damage to the subway station structure is greater in the TK earthquake. At loading levels above 0.3 g, the second plateau in the WC earthquake significantly increases the peak IDR and residual displacements, resulting in the greater probability of severe damage or even collapse of the structure.

     

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