边柱失效后RC板柱结构连续倒塌性能试验研究

制作了2个缩尺比例为1/3.5的单层1×2跨的RC板柱子结构试件，对其开展了边柱失效情况下的静力倒塌试验，研究其倒塌破坏模式和破坏机理等连续倒塌性能，探讨混凝土板底配置斜向构造钢筋对RC板柱结构连续倒塌性能的影响。试验结果表明：在失效柱节点区发生冲切破坏后，相邻角柱和边柱的节点区域先后发生弯剪破坏；加载过程中混凝土板顶面和底面分别形成了以失效柱为中心的弧形裂缝分布和放射型裂缝分布；由失效柱承担的荷载在剩余结构中主要沿楼盖板的短跨向相邻柱传递；与未配置板底斜向构造钢筋的试件相比，配置板底斜向构造钢筋试件的开裂荷载、第1个峰值荷载和极限抗倒塌承载力分别提高了78.3%、32.3%和50.7%；布置斜向板底构造钢筋的试件在倒塌过程中荷载动力增大系数（DIF）的最大值和波动幅度均明显减小。分析可知，拉膜效应是板柱结构中一种重要的抗倒塌工作机制；在对边柱失效情况下的板柱结构开展静力倒塌分析时荷载动力增大系数（DIF）的取值既不应小于1.16，也不应大于2.0；配置板底斜向构造钢筋可以作为提高RC板柱结构薄弱区域抗连续倒塌性能的一种有效构造措施。最后，基于试验提出了边柱失效情况下板柱结构的抗倒塌承载力计算模型，计算值与试验值的对比表明该计算模型可用于对边柱失效情况下板柱结构抗倒塌承载力的评估。

Experimental Study on Progressive Collapse Performance of RC Flat Plate Structures in the Scenario of Side Column Loss

Two 1/3.5 reduced scale one-story 1 × 2 bay reinforced concrete (RC) flat plate sub-structures were fabricated and static progressive collapse tests in the scenario of a side column loss were carried out on them. Progressive collapse performance such as collapse failure modes and mechanism was investigated and the influence of diagonal constructional slab bottom reinforcement (DCSBR) on the progressive collapse performance of RC flat plate structures was discussed. Experimental results showed that, after punching failure happened in the joint region of the removed column, bending-shear failure was observed in the joint regions of adjacent corner column and side column successively. Arc-shaped cracks on the slab top and radial cracks on the slab bottom distributed around the removed column appeared during loading. Load carried by the removed side column was mainly transmitted along the short slab span to the adjacent column in the residual structures. Comparing with the specimen without DCSBR,the crack load, the first peak load and the ultimate collapse resistance of the specimen with DCSBR improved by 78.3%, 32.3% and 50.7%, respectively. The maximum value and fluctuation range of the dynamic increase factor (DIF) of load reduced obviously for the specimen with DCSBR. The analysis showed that tensile membrane action was one of the most important working mechanisms against collapse in flat plate structures. When static method was used to analyze the collapse performance of flat slab structures, DIF of load should be greater than 1.16 and less than 2.0. DCSBR can be used as an efficient constructional method to improve the collapse resistance of weak regions in flat plate structures. Finally, the collapse resistance calculation model of flat slab structures in the scenario of a side column loss was presented based on the experimental results, and the comparison of calculations with experiments indicated that the calculation model can be used to assess collapse resistance of flat plate structures in the scenario of a side column loss.