【作者】 谭清华；

【导师】 韩林海；

【作者基本信息】 清华大学 ， 土木工程， 2012， 博士

【摘要】 深入研究遭受包括升、降温过程的全过程火灾作用后型钢混凝土结构的力学性能，对合理进行型钢混凝土结构的抗火设计及其火灾后性能评估具有重要的理论意义和应用价值。本文对火灾作用后型钢混凝土柱和型钢混凝土柱—混凝土梁平面框架的力学性能进行研究，主要研究内容和取得的成果如下：1.进行了五根型钢混凝土柱和十榀型钢混凝土柱—混凝土梁平面框架在外荷载和火灾升、降温共同作用下的力学性能试验，深入研究了型钢混凝土柱和型钢混凝土柱—混凝土梁平面框架的特征截面的温度分布、梁柱变形、典型破坏形态以及火灾后剩余承载力等的变化规律。2.编制了可自动识别和转换材料不同阶段本构关系、考虑混凝土高温徐变和瞬态热应变以及高强混凝土高温爆裂影响的计算程序；建立了在外荷载和火灾升、降温共同作用下型钢混凝土柱和型钢混凝土柱—混凝土梁平面框架的有限元模型，该模型得到了试验结果的验证。3.基于建立的有限元模型，对型钢混凝土柱和型钢混凝土柱—混凝土梁平面框架的温度场分布及其在外荷载和火灾升、降温共同作用下的变形特点、破坏形态、应变分布、内力重分布和火灾后剩余承载力等进行了深入研究。4.对影响型钢混凝土柱火灾后剩余承载力系数的各参数进行了分析计算，结果表明，升温时间、截面周长、长细比和混凝土强度是影响型钢混凝土柱火灾后剩余承载力系数的主要因素；对影响火灾后型钢混凝平面框架柱计算长度系数的各参数进行了计算，结果表明，升温时间、梁柱线刚度比、柱混凝土强度、水平向约束刚度比、竖直向约束刚度比和面内转动约束刚度比是影响型钢混凝土平面框架柱火灾后计算长度系数的主要因素；在此基础上，给出了火灾后型钢混凝土柱剩余承载力系数和框架柱计算长度系数的实用计算方法。更多还原

【Abstract】 A thorough study on performance of steel reinforced concrete (SRC)structures under the coupled loading and full-range fire with both heating andcooling, is of theoretical and applied significance for fire safety design andassement of a SRC structure after fire exposure. Performance of SRC columnsand SRC column to reinforced concrete (RC) beam portal frames are thusinvestigated after exposure to fire.The main research work and results of the current thesis is as follows:1. Experiments were conducted on five SRC columns, ten SRC column toRC beam portal frames after exposure to fire. The time relationships oftemperature field of characteristic cross-section, deformations of columns andbeams, typical failure modes and residual load bearing capacities of the SRCcolumns and SRC column to RC beam portal frames were analyzed.2. Several subroutines, including material constitutive relations conversion,concrete thermal creep strain, concrete instantaneous thermal strain andexplosive spalling of high strength concrete were developed. Finite elementanalysis (FEA) models of SRC columns and SRC column to RC beam portalframes under the full-range fire were then established and were verified by thetests.3. Based on the verified FEA models, the temperature distributions,deformations, failure modes, strain distributions, internal force redistributionand residual load bearing capacities of the SRC columns and SRC column to RCbeam portal frames under the combined fire and loading sequences wereanalyzed.4. Influences of various parameters on the residual load bearing capacitycoefficient of the SRC columns were calculated. It is found that, in general,heating time, perimeter of column section, slenderness ratio and concretestrength clearly affect the residual load bearing capacity coefficient of the SRCcolumns. Influences of various parameters on the equivalent length of the SRCcolumn in the SRC portal frames after exposure to fire were also investigated. It is found that the heating time, beam-column linear stiffness ratio, columnconcrete strength, stiffness ratios of the horizontal restraint spring, the verticalrestraint spring and the rotational restraint spring clearly affect the equivalentlength of the SRC column in the SRC portal frames after fire. Tables forcalculating the residual load bearing capacity coefficient of the SRC columns, aswell as the equivalent length of the SRC column in the SRC portal frames afterfire were proposed finally.更多还原