双向地震动下单层偏心体系基于IDA的地震易损性分析

考虑实际地震动的多维性以及偏心引起结构多分量反应的耦合作用,建立了屈服准则符合二维屈服函数三自由度的单层偏心体系模型。选取了24组双向地震动记录作为水平激励进行增量动力分析。以地震峰值加速度为地震强度参数,分别以x分量的延性系数μ和扭转分量的最大扭转角θ为抗震性能参数建立平动能力曲线和扭转能力曲线。分析了偏心率e/r、频率比Ω_θ和场地类别等对两种能力曲线的影响。结果表明:e/r和Ω_θ对单层偏心体系平动反应的影响可忽略不计,但对扭转反应的影响明显。失效指标相同的前提下,场地土越硬,相同地震强度下的单层偏心体系抗震失效的概率越低。

IDA-based Seismic Fragility Analysis for One-story Asymmetric Plan Systems Under Bi-directional Earthquake Motions

Considering the multi-dimensional feature of earthquake motions and coupling effect of multi-component reactions caused by eccentricity, the one-storey asymmetric plan system with three-degree freedom is established in which the yielding rule of this asymmetric system is determined by two-dimensional yield-surface plasticity function. 24 bi-directional earthquake motion records for hard, intermediate and soft soil sites are selected as the excitations of this asymmetric system. The increment dynamic analysis for this system is conducted, and translational capability curves and torsion capability curves are given in which peak ground acceleration is used as earthquake intensity parameter, the ductility factor μ and the maximum rotation angle θ are used as performance parameters, respectively. The effect of eccentricity e/r, frequency ratio Ω_θ and the kinds of soils are analyzed based on the two types of capability curves. The results show that the effect of e/r and Ω_θ on the translational responses of the system is negligible, but it has an obvious effect on the torsional responses of the system. On the premise of the same failure index, the harder the soil is, the lower the seismic failure probability for the asymmetric plan under the same earthquake intensity is.