火灾下带肋薄壁方钢管混凝土柱承载力分析

Analysis on Load Bearing Capacity of Concrete-Filled Stiffened Thin-Walled Steel Tubular Columns with Square Cross-Section under Fire

对带肋薄壁方钢管混凝土柱在火灾下的承载力进行了分析,考察了各重要参数对构件承载力影响系数的影响。结果表明:在火灾作用下,带肋薄壁方钢管混凝土柱的承载力损失较为严重,在一定参数范围内,截面尺寸、构件长细比和防火保护层厚度对火灾下构件承载力影响系数的影响较大,荷载偏心率、截面含钢率的影响次之,钢管屈服强度、加劲肋屈服强度、混凝土抗压强度的影响较小,加劲肋宽厚比在荷载比≤0.3且宽厚比≤25的情况下有一定影响。在构件外表面采用防火保护能有效提高耐火极限,而且厚涂型钢结构防火涂料的效果明显优于水泥砂浆保护层。

The load bearing capacity of concrete-filled stiffened thin-walled steel tubular columns with square cross-section under fire was analyzed,and the influences of important parameters on influential coefficient of load bearing capacity were investigated.It was found that,the load bearing capacity of concrete-filled stiffened thin-walled steel tubular columns with square cross-section under fire loses seriously.Within the certain range of parameters,section dimension,member slenderness ratio and fire protection thickness have great influence on the influential coefficient of load bearing capacity.The influences of load eccentricity and section steel ratio are moderate,and the influences of yield strength of steel tube and stiffeners,concrete compressive strength are lesser.The width-to-thickness ratio of stiffener has certain influence under the condition that the load level is not more than 0.3 and the width-to-thickness ratio is not more than 25.Fire protection on outside surface of members can improve fire resistance and the effect of thick fire retardant coating for steel structure is superior to that of cement mortar obviously.