周围结构约束对规则RC框架抗连续倒塌易损性影响研究

Study on Influence of Peripheral Structural Constraints on Progressive Collapse Fragility of Regular RC Frames

摘要:

RC 框架发生连续倒塌时，失效区域边界约束条件会影响结构的抗力机制。为探讨周围结构约束对规则 RC 框架抗连续倒塌易损性的影响，采用易损性分析方法，对典型规则 RC 框架进行抗连续倒塌性能评估，系统分析了不同内柱、边柱失效工况下，规则 RC 框架抗连续倒塌易损性曲线及鲁棒性指标。研究结果表明：（1）结构顶层的不同内柱、边柱移除时，周围结构约束对结构抗连续倒塌易损性影响显著。在其他楼层，由于上部结构的备用传递路径较多，不同内柱、边柱移除的连续倒塌易损性曲线较为接近；（2）相比边柱移除工况，周围结构约束对内柱移除工况下的结构抗连续倒塌易损性影响更为显著；（3）在结构顶层，周围结构约束越强，该工况下结构抗连续倒塌鲁棒性越强，当移除柱周围结构跨数大于 2 时，不同约束导致的抗连续倒塌易损性差异较小；（4）构件截面一致时，结构总楼层数对周围结构的约束效应影响较小。

Abstract:

When reinforced concrete (RC) frames undergo progressive collapse, the boundary constraint conditions of the failed region can affect the structural resistance mechanism. To investigate the influence of peripheral structural constraints on the progressive collapse fragility of regular RC frames, a fragility analysis method was employed to assess the progressive collapse resistance of typical regular RC frames. The fragility curves and robustness indicators of regular RC frames under different failure scenarios of internal and edge columns were systematically analyzed. The results showed that: (1) when different internal columns or edge columns on the top floor of the structure were removed, the peripheral structural constraints had significant effects on the progressive collapse fragility of the RC frames. On other stories, due to the presence of multiple alternative load paths in the upper structure, the progressive collapse fragility curves under the removal of different internal and edge columns were relatively similar. (2) Compared to edge column removal scenarios, the peripheral structural constraints had a more significant impact on the progressive collapse fragility under internal column removal scenarios. (3) On the top floor of the structure, the stronger the peripheral structural constraints were, the stronger the robustness of the RC frames against progressive collapse under the column removal scenario became. When the peripheral structure around the removed column encompassed more than two spans, the differences in progressive collapse fragility caused by different constraints became relatively small. (4) When member cross-sections were consistent, the total number of stories in the structure had little effect on the constraining effects of peripheral structure.