多层RC框架底层中柱失效连续倒塌计算模型  

Analytical Model for Progressive Collapse of Multi-story RC Frame after a Ground-story Middle Column Removal

作　　者：林楷奇 李道远 蔡亮 LIN Kaiqi;LI Daoyuan;CAI Liang(College of Civil Engineering,Fuzhou University,Fuzhou 350116,China;Sustainable and Innovative Bridge Engineering Research Center of Fujian Province University,Fuzhou 350108,China;Fujian Provincial Key Laboratory on Multi-Disasters Prevention and Mitigation in Civil Engineering,Fuzhou 350116,China)

机构地区：[1]福州大学土木工程学院,福建福州350116 [2]可持续与创新桥梁福建省高校工程研究中心,福建福州350108 [3]福建省土木工程多灾害防治重点实验室,福建福州350116

出　　处：《防灾减灾工程学报》2024年第6期1299-1310,1335,共13页Journal of Disaster Prevention and Mitigation Engineering

基　　金：国家自然科学基金项目(52278491,51908133);福建省自然科学基金项目(2022J05119)资助。

摘　　要：多层RC框架结构在底层中柱失效后,不平衡荷载由失效柱上方各楼层共同承担,其承载力相比单层框架会大幅提升。然而,由于缺乏系统的多层RC框架连续倒塌试验和数值模拟研究,失效柱上部各楼层的连续倒塌抗力机制尚不明确,既有研究中关于多层RC框架结构的抗连续倒塌承载力理论分析模型也十分有限。为此,首先依照中国规范设计了9座典型的RC框架结构,采用OpenSees开展了各框架在底层中柱失效时的连续倒塌分析,系统研究了各楼层梁的内力及应变分布,讨论了不同楼层的梁内连续倒塌抗力发展机制。在此基础上,结合单层RC框架梁柱子结构的连续倒塌承载力计算模型,依据各层梁的抗力贡献,建立了多层RC框架底层中柱失效的连续倒塌抗力计算模型,并与试验及数值模拟结果进行了对比验证。研究结果表明:(1)底层中柱失效后,多层RC框架首层梁存在显著的压拱机制和悬链线机制;(2)多层RC框架结构沿楼层高度方向布置不同尺寸构件时,截面尺寸变化的下部楼层梁会存在压拱受力机制;(3)除上述楼层外,其他楼层梁主要通过受弯机制提供连续倒塌抗力;(4)所提计算模型能较准确计算多层RC框架底层中柱失效时的抗连续倒塌承载力。In a multi-story RC frame,when the ground-story middle column fails,the unbalanced load is borne by the stories above the failed columns,and the load-carrying capacity is significantly in-creased compared to a single-story frame.However,due to the lack of systematic experimental and nu-merical investigations on the progressive collapse resistance of spatial multi-story RC frames,the force mechanisms of the stories above the failed column for resisting progressive collapse are still un-clear.Moreover,there are few analytical models for quantifying the progressive collapse resistance of multi-story RC frame structures among existing studies.Therefore,9 typical multi-story RC frames are designed following the Chinese design codes and their progressive collapse behaviors under the ground-story middle column removal scenario are analyzed.The internal forces and strain develop-ments of the beams on each story are systematically analyzed.And the progressive collapse-resisting mechanisms of various stories in an RC frame are discussed.On this basis,the calculation model of single-story RC beam-column substructures is combined to establish the analytical model for quantify-ing the progressive collapse resistance of a multi-story RC frame after the ground-story middle column removal,by calculating the resistance contributions of different stories.The experimental tests and nu-merical simulations are compared with the calculated results to verify the accuracy of the proposed model.The results show that:(1)Following the removal of the column,significant compressive arch action and catenary action are observed in the ground story beams.(2)When components of varying di-mensions are arranged vertically within the RC frame,compressive arch action is observed in the low-er floor beams that experience a change in component size.(3)Apart from the aforementioned floors,beams on other floors generally exhibit progressive collapse resistance through flexural actions.(4)The proposed analytical model can provide a satisfying estimation

关 键 词：多层RC框架 连续倒塌 数值模拟 受力机制 计算模型 

分 类 号：TU398.9[建筑科学—结构工程]