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为研究相对两面受火的方钢管约束型钢混凝土柱的耐火极限,运用 ABAQUS 建立了 ISO 834 标准火灾作用下方钢管约束型钢混凝土柱的有限元模型,包括温度场分析模型和耐火极限分析模型,用已有的相关试验进行验证,并分析了截面温度场和力学性能的变化规律.在此基础上分析荷载比、计算长度、型钢含钢率、截面尺寸、混凝土强度等参数对构件耐火极限的影响规律.基于上述规律并结合大量计算结果定量给出了相对两面受火的方钢管约束型钢混凝土柱的耐火极限简化计算式.结果表明:荷载比和计算长度对构件耐火极限影响较大,随着荷载比和计算长度的增加,构件的耐火极限呈线性降低;截面尺寸对构件的耐火极限影响较大,随着截面尺寸的增加,构件的耐火极限呈线性增加;随着型钢含钢率的增加,构件的耐火极限增加并不明显;耐火极限计算式计算精度良好,可为相对两面受火的方钢管约束型钢混凝土柱抗火设计提供参考.“,”In order to study the fire resistance of square tubed steel reinforced concrete columns in relative fires，the finite element model of square tubed steel reinforced concrete columns under ISO 834 standard fire curve was established by using ABAQUS, including temperature field analysis model and fire resistance analysis model. The model was analyzed and verified by the existing related experiments. The change rules of the temperature field and mechanical properties of the section were analyzed. On this basis，the influences of load ratio，calculation length，steel content of steel，dimensions，concrete strength and other parameters on the fire resistance of the component were analyzed. Based on the above rules and combined with a large number of calculation results，the simplified calculation formula for the fire resistance of the confined steel concrete columns with square steel tubes on two sides subjected to fire was given quantitatively. The results show that the load ratio and the calculated length have great influence on the fire resistance，with the increase of the load ratio and the calculation length，the fire resistance of components decrease linearly. The section dimensions has a greater influence on the fire resistance of the component，and the fire resistance of the component increases with the section dimensions. With the increase of the steel content of steel，the increase of the fire resistance of the components is not obvious. The formula has a good calculation accuracy and can be used for the concrete column fire resistance of square steel tubes confined by two sides of fire.