Inclined collapse of structures under strong earthquakes threatens the adjacent infrastructures. The collapse mode and collapse direction should be considered with caution to curb the secondary disaster in the urban area. However, current studies on the inclined collapse mechanism are predominantly limited to the qualitative and intuitive understanding. To fill this gap, this study presents an insight into the inclined collapse mechanism of the reinforced concrete (RC) frame structures with two typical features subjected to earthquakes, i.e., the structures with slab opening on one side of the first floor and the structures with disparate axial compression ratios of the first story columns on the opposite sides. First, shaking table tests were performed on two 1/10-scale three-story RC frame structure models undergoing inclined collapse. Then the multi-scale finite element models were established, validated against the test results and used for parametric studies. In the parametric studies, two coefficients were considered to describe the typical features of the RC frame structures, i.e., the strong column-weak beam ratio and differential rate of the axial compression ratios . The test and numerical results found that the inclined collapse mechanism was attributed to the different distributions and discrepant resistance deterioration of the plastic hinges among the first story columns of the RC frame structures with the two features. This causes the inconsistent damage levels among the first story columns, the dominant direction of the lateral displacement, and the inclined collapse of the structures. Finally, the collapse mode and collapse direction can be controlled by appropriately adjusting the two coefficients and for the structures with the typical features concerned in this study.

中文翻译：

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RC框架结构地震倾斜倒塌机理振动台试验

强震下建筑物的倾斜倒塌威胁着邻近的基础设施。应慎重考虑崩塌模式和崩塌方向，遏制城区次生灾害。然而，目前对倾斜塌陷机制的研究主要局限于定性和直观的理解。为了填补这一空白，本研究深入探讨了具有两种典型地震特征的钢筋混凝土（RC）框架结构的倾斜倒塌机制，即首层一侧板开孔结构和首层一侧板开孔结构。相对两侧第一层柱的轴向压缩比不同。首先，对两个1/10比例的三层RC框架结构模型进行倾斜倒塌振动台试验。然后建立多尺度有限元模型，根据测试结果进行验证并用于参数研究。在参数化研究中，考虑了两个系数来描述RC框架结构的典型特征，即强柱弱梁比和轴压比差率。试验和数值结果发现，倾斜倒塌机理是由于具有这两种特征的RC框架结构首层柱间塑性铰的分布不同和抗力劣化差异不同造成的。造成首层柱间损伤程度不一致、侧向位移主导方向不一致、结构倾斜倒塌。最后，对于本研究具有典型特征的结构，可以通过适当调整这两个系数来控制倒塌模式和倒塌方向。