【作者】 宋天诣；

【导师】 韩林海；

【作者基本信息】 清华大学 ， 土木工程， 2010， 博士

【摘要】 钢-混凝土组合框架结构在建筑工程中已得到较广泛应用,深入研究火灾升、降温作用下钢-混凝土组合框架梁-柱连接节点的力学性能,对于整体组合框架结构抗火设计及其火灾后评估具有重要意义。本文以实际工程中常用的钢管混凝土柱-组合梁、型钢混凝土柱-型钢混凝土梁中柱节点为研究对象,对这两类节点在经历火灾升、降温过程后的工作机理进行了深入研究。主要研究工作如下:1.对钢管混凝土柱-组合梁节点和型钢混凝土柱-型钢混凝土梁节点在外荷载作用下,楼板下部遭受火灾升、降温过程后的力学性能进行了试验,深入研究了节点的温度分布、结构变形和材料应变、以及节点火灾作用后剩余承载力的变化规律。2.分析确定了常温、升温、降温和高温后各阶段钢和混凝土的热力学性能,编制了材料本构关系模型转换子程序和可模拟钢材高温蠕变的子程序。结合有限元分析平台ABAQUS,建立了钢管混凝土柱-组合梁节点和型钢混凝土柱-型钢混凝土梁节点的有限元分析模型,实现了对升、降温火灾和外荷载共同作用下两类节点的受力全过程分析。进行了型钢混凝土柱耐火极限的验证性试验,并收集了有关试验数据对有限元模型进行了验证。与试验结果的对比分析表明,该有限元分析模型具有较好的精度。3.采用建立的有限元分析模型,对钢管混凝土柱-组合梁节点和型钢混凝土柱-型钢混凝土梁节点在外荷载和火灾升、降温共同作用下的温度场分布、节点破坏形态、变形特点、应力和应变分布、内力变化、节点弯矩-梁柱相对转角关系等的变化规律进行了深入研究。4.对外荷载和火灾升、降温共同作用下,影响钢管混凝土柱-组合梁节点和型钢混凝土柱-型钢混凝土梁节点弯矩-转角关系的各种参数,如升温时间比、柱火灾荷载比、梁火灾荷载比、梁柱线刚度比和极限弯矩比、截面含钢率、混凝土和钢材强度等进行了分析计算,研究了上述各参数对钢-混凝土组合框架梁-柱连接节点火灾后剩余刚度系数和承载力系数的影响规律,给出了剩余刚度系数和承载力系数的实用计算方法。更多还原

【Abstract】 Steel-concrete composite structures have been widely used in construction projects in recent years. It is very important to study the performance of steel-concrete composite beam-column joints subjected to a fire including the heating and cooling phases for the structural fire safety design and after-fire evaluation. Concrete filled steel tubular (CFST) colum to composite beam joints and steel reinforced concrete (SRC) column to SRC beam joints, which have been used widely in real projects, are chosen as the research objects. The performance of two types of composite beam-column joints are studied in a life-time loading sequences including initial loading, heating, cooling and post-fire loading.The main research work includes:1. Experiments were carried out on CFST column to composite beam joints and SRC column to SRC beam joints after exposed to heating and cooling fire with initial loads. The temperature distributions, deformations, strains and residual load bearing capacities of joints were analyzed.2. After the determinations of material properties in ambient, heating, cooling and post-fire phases, finite element analysis (FEA) models of CFST column to composite beam joints and SRC column to SRC beam joints were established in ABAQUS, for which, material constitutive relations conversion and steel high-temperature creep modelled using the subroutine. The FEA models can be used to analyze the entire process of the two types of joints under the combined loads and fire including heating and cooling phases. The accuracy of FEA models were verified by the test results including fire resistance tests of SRC columns carried out by the author.3. The temperature distributions, failure modes, deformations, stress and strain distributions, internal force, moment versus rotation angle relations of CFST column to composite beam joints and SRC column to composite beam joints under the combined loads and fire including heating and cooling phases were analyzed using the established FEA models. 4. Influences of parameters, such as heating time ratio, load ratios of column and beam, beam-column linear stiffness ratio, beam-column ultimate moment ratio, steel ratio, concrete strength and steel yield stress on the moment versus rotation angle relations of CFST column to composite beam joints and SRC column to SRC beam joints under combined loads and fire were analyzed. Simplified formulas for calculating the residual stiffness ratio and residual load bearing capacity ratio of the two types of composite joints were proposed.更多还原