考虑梁端约束CFST柱-RC梁节点耐火性能研究

Fire Performance of CFST Column to RC Beam Joints with Beam Ends Constrained

针对火灾下钢管混凝土(CFST)柱-钢筋混凝土(RC)梁节点的力学性能,建立了火灾下节点温度场和力学场分析的有限元模型,并利用已有试验结果验证了有限元模型的有效性。研究了材料参数、几何参数、荷载参数及梁端约束刚度对CFST柱-RC梁节点耐火极限的影响,重点考察了梁端轴向和转动约束刚度对火灾下CFST柱-RC梁节点弯矩-转角关系、转动刚度和截面内力分布规律的影响。结果表明,CFST柱-RC梁节点在火灾下有两种破坏形态:柱破坏和梁板破坏,梁端约束对CFST柱-RC梁节点耐火极限的影响较小,但梁端轴向约束对火灾下CFST柱-RC梁节点弯矩—转角关系、转动刚度和截面内力分布规律的影响显著。

A finite element analysis（FEA）model was developed for sequentially coupled heat transfer and mechanical analysis of concrete filled steel tube（CFST）column to reinforced concrete（RC）beam joints under fire,which was validated by the experimental results available in the literature.The FEA model was then used to investigate the influence of material parameters,geometric parameters,load parameters and the constrained stiffness at beam ends on the fire resistance of CFST column to RC beam joints,and particularly the effect of axial and rotational constrained stiffness at beam ends on the moment versus rotation angle relationship,rotational stiffness and distribution of sectional inner forces of CFST column to RC beam joints in fire.The results show that CFST column to RC beam joints have two kinds of failure model：column failure and beam-slab failure.The constraint at beam ends has little influence on the fire resistance of CFST column to RC beam joints;however,the axial constraint has a significant impact on the moment versus rotation angle relationship,rotational stiffness and distribution of sectional inner forces of the composite joints in fire.