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合理确定了高温下钢材和混凝土的热工参数和热-力本构关系,根据构件截面温度场分布,提出了计算火灾下方钢管配筋混凝土柱力学性能的理论分析模型,模型中考虑了钢材的高温蠕变、混凝土的瞬态热应变和高温徐变,计算结果得到了以往实验结果的验证。在此基础上,分析了配筋率和钢筋屈服强度对方钢管配筋混凝土柱耐火极限的影响规律。结果表明,对于专门考虑抗火作用钢筋的构件,配筋率1%～5%可比钢管素混凝土柱耐火极限提高约10%～60%,构件的耐火极限随钢筋屈服强度的增加而稍有增长。对于荷载比已包含钢筋受力作用的构件,配筋率和钢筋屈服强度对耐火极限的影响很小。
Based on the distribution of temperature field in the cross section of the member, a theoretical analysis model for calculating the mechanical properties of steel reinforced concrete columns under fire is proposed. The model takes into account the thermal properties of steel and concrete under high temperature. High temperature creep, transient thermal strain of concrete and high temperature creep. The calculation results are verified by previous experimental results. On this basis, the influence of reinforcement ratio and yield strength on the fire resistance of reinforced concrete columns reinforced by square steel tube is analyzed. The results show that the reinforcement ratio of 1% ~ 5% is about 10% ~ 60% higher than that of the concrete filled steel tubular columns, and the fire resistance of the components increases slightly with the increase of the yield strength . For components with load-bearing ratio that already include the force of reinforcement, the effect of reinforcement ratio and yield strength on the fire-resistance limit is small.