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采用考虑高温蠕变的钢材热-力耦合本构关系及考虑高温徐变和瞬态热应变的混凝土热-力耦合本构关系模型,利用ABAQUS有限元分析软件建立火灾下钢管混凝土柱、钢-混凝土组合梁等构件以及节点和单层单跨框架结构的温度场和结构抗火分析的有限元分析模型,计算结果得到已有试验结果的验证。在此基础上设计一榀3层3跨钢-混凝土组合平面框架模型,建立局部火灾下该平面框架的温度场与结构抗火性能分析模型,研究局部火灾下钢-混凝土组合平面框架的抗火性能并分析其失效模式,对该平面框架的耐火极限、梁柱变形规律及柱底截面内力变化规律进行分析,并对是否考虑钢梁与混凝土板相互作用对框架梁抗火性能的影响进行研究,对梁先失效模式下框架梁与简支梁、固支梁的抗火性能进行对比分析,对柱先失效模式下钢管混凝土框架柱与两端固支钢管混凝土单柱的抗火性能进行对比分析。结果表明:梁先失效模式下考虑钢梁与混凝土板的相互作用可以充分发挥钢-混凝土组合梁的抗火性能,框架梁的抗火性能要优于简支梁且接近并略低于固支梁,柱先失效模式下两面受火时单个钢管混凝土边柱的抗火性能为框架边柱抗火性能的上限,两面受火与四面受火时单个钢管混凝土中柱的抗火性能与相应框架中柱的抗火性能较接近。
The constitutive model of thermo-mechanical coupling of steel considering creep at high temperature and thermo-mechanical coupling constitutive model of concrete subjected to high temperature creep and transient thermal strain were established. By using ABAQUS finite element analysis software, the concrete filled steel tubular columns, steel- Concrete composite beams and other components as well as the temperature field and the finite element analysis model of the node and single-layer single-span frame structure. The calculated results are validated by the existing experimental results. On this basis, a three-level three-span steel-concrete composite plane frame model was designed and the temperature field and the structural fire resistance analysis model of the plane frame under local fire were established. The fire resistance of the steel-concrete composite plane frame under partial fire The failure modes of the frame and the fire resistance of the plane frame, the deformation law of the beam and column and the internal force variation of the column bottom section are analyzed. The influence of the interaction between the steel beam and the concrete slab on the fire resistance of the frame beam is also studied. The comparative analysis of the fire resistance between the frame beam and the simply supported beam and the fixed beam under the beam first failure mode is conducted to compare the fire resistance of the concrete filled steel tubular column and the single-column reinforced concrete filled steel tubular column with the first failure mode. The results show that considering the interaction between steel beam and concrete slab in beam failure mode, the fire resistance of steel-concrete composite beam can be fully exerted. The flame resistance of frame beam is better than that of simply supported beam and close to and slightly lower than that of solid beam The fire resistance performance of single concrete filled steel tubular column with two sides subjected to fire in beam and column failure mode is the upper limit of the flame resistance of the frame side column. The fire resistance of the single concrete filled steel tubular column and the corresponding frame Fire resistance of the column is closer.