考虑约束作用的混凝土柱耐火试验加载方式研究

Study on Loading Method of Fire Test for Reinforced Concrete Frame Column Considering Constraint

为找到一种在构件耐火试验中能有效考虑整体结构对受火构件约束作用的加载方式,建立了2层2跨的钢筋混凝土框架和受火单柱的有限元模型,对比分析荷载比为0.2、0.4和0.6时,恒载、变位移加载、变力加载和交互加载方式下受火单柱与整体结构的内力、变形和耐火极限的差异。研究结果表明:恒载单柱不能准确反映整体结构受火柱的变形、轴力和耐火极限;变位移加载和变力加载在荷载比为0.2时能较好考虑整体结构中的约束作用,在荷载比为0.4和0.6时误差增大也不能准确反映整体结构的抗火性能;交互加载的相对误差随荷载比增大而增大,且最大误差小于20%。恒载、变位移加载、变力加载和交互加载中,交互加载可以较好考虑整体结构中的约束作用,近似达到整体结构试验的效果。

In order to find a loading method that can effectively consider the constraint of the whole structure in the component fire resistance test,the finite element models of a two-story two-span rein-forced concrete frame and a single column subjected to fire were established.The differences in inter-nal force,deformation and fire resistance limit between the single column and the whole structure un-der constant loading,variable displacement loading,variable force loading and interactive loading were compared and analyzed when the load ratios are 0.2,0.4 and 0.6.The results show that the sin-gle column under constant load cannot accurately reflect the deformation,axial force and fire resis-tance limit of the overall structure.The constraint in the whole structure can be considered by variable displacement loading and variable force loading when the load ratio is 0.2.The fire resistance of the whole structure cannot be performed accurately with an increasing error when the load ratio is 0.4 and 0.6.The relative error under interactive loading increases with the increase of load ratio and the maxi-mum error is less than 20%.Among the constant loading,variable displacement loading,variable force loading and interactive loading,the constraint in the whole structure can be better considered by interactive loading,approximately achieving the effect of the whole structure test.