火灾中钢筋混凝土两端固结梁破坏模式变化规律  

Change Law of Failure Modes of Reinforced Concrete Beams with Fixed Ends in Fire

作　　者：王玉镯[1,2] 邱昊 徐天贵 李心宇 WANG Yuzhuo;QIU Hao;XU Tiangui;LI Xinyu(School of Civil Engineering,Shandong Jianzhu University,Jinan 250101,China;Key Laboratory of Building Structure Reinforcement and Underground Space Engineering,Ministry of Education,Shandong Jianzhu University,Jinan 250101,China;Key Laboratory of Concrete and Prestressed Concrete Struc-tures of Ministry of Education,Southeast University,Nanjing 210096,China;School of Civil Engineering,South-east University,Nanjing 210096,China)

机构地区：[1]山东建筑大学土木工程学院,山东济南250101 [2]山东建筑大学建筑结构加固改造与地下空间工程教育部重点实验室,山东济南250101 [3]东南大学混凝土与预应力混凝土教育部重点实验室,江苏南京210096 [4]东南大学土木工程学院,江苏南京210096

出　　处：《防灾减灾工程学报》2024年第1期192-201,共10页Journal of Disaster Prevention and Mitigation Engineering

摘　　要：为了研究火灾过程中钢筋混凝土两端固结梁破坏模式的变化规律,利用有限元分析软件对梁内部的温度场进行分析,确定其不同耐火时刻的分布规律,利用承载力简化计算公式对火灾过程中钢筋混凝土梁不同时刻的极限承载力进行计算分析。并对上侧纵筋配筋面积、混凝土保护层厚度和混凝土强度为变换因素的三组固结梁试件进行理论分析,讨论了火灾过程中不同参数对钢筋混凝土固结梁破坏模式临界点ξ变化规律的影响。结果表明:上侧纵筋配筋面积越大,ξ点对应受火时间T越提前;混凝土保护层厚度越大,混凝土强度越高,ξ点对应受火时间T越滞后。在理论计算的基础上,为保证梁在受火两小时内发生弯曲破坏,对梁的防火设计提供了思路。本研究方法可以简化分析钢筋混凝土梁高温中破坏模式的变化规律,为火灾中构件的设计计算提供参考。In order to study the changes in the failure modes of reinforced concrete beams with fixed ends in fire,the temperature field inside a beam was analyzed using finite element analysis software and its distribution at different fire resistance times was determined.The ultimate bearing capacity of the reinforced concrete beam at different fire times was calculated using the simplified calculation for-mula of bearing capacity.Theoretical analysis was conducted on three sets of beam specimens with fixed ends,taking the upper longitudinal reinforcement area,concrete cover thickness,and concrete strength as transformation factors.The influence of different parameters on the changes of critical pointξin the failure mode of the reinforced concrete beams during fire was discussed.The results show that the larger the reinforcement area of the upper longitudinal reinforcement,the earlier the fire time T of the pointξ.The thicker the concrete protective layer and the higher the strength of the con-crete,the later the fire time T corresponds to the pointξ.To ensure that the beams undergo bending failure within two hours of being exposed to fire,ideas for the fire protection design of beams are pro-vided based on theoretical calculations.The presented method can simplify the analysis of the changes in failure modes of reinforced concrete beams at high temperatures,and provide a reference for the de-sign and calculation of components in fires.

关 键 词：固结梁 破坏模式 火灾过程 简化计算 极限承载力 

分 类 号：TU375[建筑科学—结构工程]