三面受火的方钢管混凝土柱耐火极限

Fire resistance limit of concrete-filled square steel tube columns exposed to three-faced fire

编制了预测方钢管混凝土柱三面火灾作用下高温反应的数值分析程序,并将之用于不同荷载比、截面边长、长细比、荷载偏心率、钢材和混凝土强度及含钢率共480种工况下方钢管混凝土柱耐火极限参数分析,得到了三面火灾作用下方钢管混凝土柱耐火极限的主要影响参数及其影响规律。基于参数分析结果,定量给出了该受火条件下方钢管混凝土柱耐火极限的简化计算方法。研究结果表明:荷载比、截面边长、长细比是三面火灾作用下方钢管混凝土柱耐火极限的主要影响参数,表现为截面边长越大,荷载比和长细比越小,构件的耐火极限越大。由于存在极强偏心,当荷载作用点偏于背火面时荷载偏心率亦有较大影响。

A numerical program aimed to predict the fire resistant response of concrete-filled SHS （Square Hollow Section） columns subjected to three-faced fire was compiled. On the basis of the program, parametric analysis of the fire resistance limit of concrete-filled SHS columns was conducted, and 480 hypothetical cases were analyzed for various parameters, including the load ratio, sectional dimensions, slenderness ratio, loading eccentricity, steel and concrete strength, and the area ratio of steel over concrete. Key parameters and their effects were obtained from the simulation results, and a simplified calculation formula for predicting the fire resistance limit was given. The a- nalysis results indicate that the load ratio, sectional dimension and slenderness ratio are main parameters that influ- ence the fire resistance limit of concrete filled SHS columns, and the fire resistance limit increases with the increase of the sectional dimensions and with the decrease of the load ratio and the slenderness ratio. The influence of the loading eccentricity is also obvious when load location trends towards the unexposed side.