高温下及高温冷却后中柱失效足尺RC梁-柱子结构抗连续倒塌性能  

Progressive collapse-resistant performance of during and after elevated-temperature full-scale RC beam-column assemblies under a middle column removal scenario

作　　者：金浏[1] 兰冬璆 张仁波[1] 钱凯 李健[1] 杜修力[1] JIN Liu;LAN Dongqiu;ZHANG Renbo;QIAN Kai;LI Jian;DU Xiuli(Key Laboratory of Urban Security and Disaster Engineering,Beijing University of Technology,Beijing 100124,China;College of Civil and Architectural Engineering,Guilin University of Technology,Guilin 541004,China)

机构地区：[1]北京工业大学城市减灾与防灾防护教育部重点实验室,北京100124 [2]桂林理工大学土木建筑工程学院,广西桂林541004

出　　处：《建筑结构学报》2024年第7期153-165,共13页Journal of Building Structures

基　　金：国家自然科学基金项目(51978022);北京市自然科学基金项目(JQ22025)。

摘　　要：为研究RC框架结构在受火工况下的破坏机理以及抗连续倒塌机制,基于热-力顺序耦合方法建立了足尺的三维有限元数值模型。在验证模型准确性的基础上,对高温下及高温冷却后的中柱失效足尺RC梁-柱子结构展开Pushdown分析,并研究了受火时间、边柱受火及抗震构造等因素的影响,并与前期基于1/2缩尺子结构展开的研究进行对比。有限元分析结果表明:在高温下,由于钢筋和混凝土力学性能的退化,子结构的第一峰荷载明显下降;当受火时间为30 min时,子结构的破坏模式与常温下相似,最终失效由靠近中柱梁端钢筋断裂控制;而当受火时间超过60 min时,子结构的破坏由梁顶部钢筋截断处的破坏控制;高温冷却后子结构可相继发展压拱机制和悬索机制抵抗倒塌,其变形能力及极限荷载与常温下相近。此外,在边柱受火时间超过60 min并冷却后,拟静力作用下子结构边柱发生轴心受压破坏;在受火时间为30~120 min时,采用抗震构造可使高温冷却后子结构的极限荷载和变形能力分别至少提高51%和39%。To study the failure mechanism and collapse-resistant mechanism of fire-exposed reinforced concrete(RC)frame structures,full-scaled three-dimensional finite element models were developed based on thermal-mechanical techniques in this study.After verifying the accuracy of the FE models,the collapse-resistant performance of full-scale RC beam-column assemblies under a middle column removal scenario during/after elevated temperature were analyzed.Based on the FE analyses,the effects of fire duration,the side column subjected to fire and seismic detailing were discussed.Furthermore,the previous research based on 1/2 scale assemblies was used to conduct comparative study.The FE results indicate that the first peak load of the assemblies significantly decreases during elevated temperature due to the degradation of properties of rebar and concrete.At a fire duration of 30 min,the failure mode of fire-exposed assemblies is similar to that of assemblies in ambient temperature,the failure of assemblies is dominated by the fracture of beam rebar at the beam ends connected to the middle column.When the fire duration exceeds 60 min,the failure of assemblies is controlled by the fracture of beam top rebar at the location of rebar curtailment.The assemblies after high temperature can develop compressive arch action and catenary action in sequence to resist collapse,and the ultimate deformation capacity and load resistance capacity are similar to those of assemblies in ambient temperature.In addition,when the side columns are exposed to fire for more than 60 min and then cooled down,they suffer compression failure under the pseudo static load.For a fire duration of 30-120min,adopting seismic detailing can increase the ultimate load and deformation capacities of the assemblies after elevated temperature by 51%and 39%at least,respectively.

关 键 词：钢筋混凝土结构 梁-柱子结构 有限元分析 高温 连续倒塌 抗力机制 

分 类 号：TU375.4[建筑科学—结构工程] TU311.41