考虑竖向地震作用效应的地下典型空间结构易损性性能指标探讨

Study on Seismic Fragility Performance Index of Typical Underground Structure Considering Vertical Seismic Effect

为探究考虑竖向地震作用效应的地下空间结构易损性性能指标,本文基于地下结构抗震分析与设计的Pushover分析方法,以六个典型地下空间结构为背景,利用ABAQUS软件建立带有附加自由场的土-地下空间结构相互作用分析模型进行Pushover分析,研究了不同类型场地及地下空间结构埋深对地下空间结构中的柱构件能力曲线的影响;采用弯矩-转角四折线模型来量化指标限值,将Pushover分析所得结果经数学统计分析,以保证率为98%的屈服转角、峰值荷载转角以及极限转角限值作为特征点,得到了适用于水平地震作用下的性能指标限值.然后,基于冲量原理分析了不同竖向地震动加速度对柱构件动力响应的影响,由拟合所得的屈服转角、峰值荷载转角以及极限转角与轴压比的关系,求得了考虑竖向地震作用效应的特征点限值折减系数,给出了考虑竖向地震作用效应的地下空间结构易损性性能指标限值.研究结果表明:地下空间结构埋深对其柱构件的能力曲线影响较大;与仅考虑水平向地震作用的结果相比较,本文算例中考虑竖向地震作用效应的特征点的平均折减系数可分别取屈服转角为0.89、峰值荷载转角为0.85、极限转角为0.80.

In order to study the seismic fragility performance index of underground structure considering vertical seismic action effect, the capacity curves of the columns have been obtained based on Pushover analysis for different sites and buried depthes through establishing the soil-underground structure interaction model with additional free field in ABAQUS. In order to determine the performance limits of different performance states, the four-line moment-drift model has been adopted, and the characteristic points of the capacity curve were chosen with yield drift, drift of maximum moment and ultimate drift at 98% guarantee rate. Then, limits of different performance states were derived. Lastly, in order to consider the effect of vertical seismic motion, the characteristic points of drifts have been modified base on the impulse theory. Then, performance limits considering vertical seismic action effect were obtained. The results demonstrate that, buried depth has a relatively big influence on the seismic performance of the columns. The average reduction coefficients of characteristic points are given as θy（0.89）、θp（0.85） and θu（0.80）.