2022年泸定地震某隔震建筑内非结构构件震害模拟分析

在2022年9月5日四川泸定地震中，位于震中近断层场地的一栋采用隔震设计的建筑内部非结构构件发生不同程度的破坏。非结构构件作为整体结构经济价值占比重要组成部分，减小其地震损伤对于建筑震后功能恢复至关重要。为此，本文在介绍该建筑内部非结构构件主要震害的基础上，采用二阶段级联分析方法。第一阶段在Etabs中建立一8层框架-剪力墙结构有限元模型，基于实测邻近台站近断层强震记录的非线性地震反应分析，模拟该建筑各楼层地震响应。第二阶段以建筑内部文件柜等常见浮放式非结构构件为原型，在OpenSees中建立零长度转角弹簧模型，基于上一阶段的结构楼面加速度响应作为输入，模拟建筑内部不同尺寸高宽比非结构构件的摇晃与倾覆响应，并同时考虑水平单向输入与水平-竖向双向输入两种方式，以重点考察近断层地震强竖向分量的影响。结果表明，隔震层能有效降低上部结构的水平楼面加速度响应，但竖向楼面峰值加速度相比竖向地面峰值加速度被显著放大；水平与竖向激励同时输入下浮放式设备的摇晃角度与倾覆概率大于水平单向激励输入的情况，考虑竖向激励的作用后会增大浮放式设备的破坏风险。因此，在近断层场地进行建筑抗震设计时，强竖向地面运动对内部非结构构件的影响不容忽视。

Seismic Damage Evaluation of Non-structural Components in an Isolated Building during 2022 Luding Earthquake

On September 5, 2022, a seismic event of magnitude 6.8 occurred in Luding, Sichuan, causing different extents of damage to non-structural components inside a seismic isolation-design building situated close to the epicenter fault. Non-structural components occupy a significant portion of the overall structural economic value, and their seismic damage is critical to post-earthquake functional recovery. Therefore, this study introduces the primary seismic damage to non-structural components within the building, following a two-stage cascading analysis approach. In the first stage, the nonlinear response history analyses of a Etabs model of the 8-story frame-shear wall building is carried out for a suite of ground motion records from adjacent monitoring stations to simulate floor seismic response. In the second stage, based on the common freestanding non-structural components such as document cabinets inside the building as prototypes, the nonlinear response history analyses of an OpenSees model of the zero-length rotation spring is carried out for a suite of floor acceleration response gained from last stage to simulate rocking and overturning response of non-structural components with different sizes and slenderness throughout the building. The rocking and overturning response of non-structural components subjected to both bidirectional and unidirectional inputs are considered, with a particular focus on the impact of the strong vertical component of the near-fault ground motion. The results show that, the isolation system effectively reduces the horizontal floor acceleration response of the upper structure. However, the vertical peak floor acceleration is significantly amplified compared to the vertical peak ground acceleration. Furthermore, when subjected to bidirection horizontal and vertical excitations, the rocking angles and the probability of overturning for freestanding non-structural component exceed those observed under horizontal unidirectional excitation. The influence of vertical excitation significantly escalates the risk of damage to freestanding equipment. Therefore, for seismic design of structures located near-fault sites, the strong impact of intense vertical ground motion on internal non-structural components cannot be ignored.