单面受火的方钢管约束钢筋再生混凝土柱耐火极限

为研究单面受火的方钢管约束钢筋再生混凝土柱的耐火极限，采用有限元软件ABAQUS建立了ISO-834标准火灾作用下单面受火的方钢管约束钢筋再生混凝土柱有限元模型，相关试验验证之后、分析了截面温度场和应力场的变化规律。在此基础上分析取代率、混凝土强度、荷载比、含钢率、荷载偏心率、荷载角、配筋率、截面尺寸和钢材强度等参数对构件耐火极限的影响规律。结果表明：荷载偏心率和荷载角对构件耐火极限影响较为复杂，当荷载角为180°时，荷载偏心率由0.2增加到0.4，构件耐火极限增加11.2%；当荷载偏心率为0.8时，荷载角由0°增到90°，构件耐火极限降低32.2%；荷载比和截面尺寸对构件耐火极限影响明显，当含钢率为5.33%时，荷载比由0.4增到0.5，其耐火极限降低37.1％；当钢材强度为Q345时，截面尺寸由200mm增到300mm时，构件耐火极限增加66.73%。基于上述规律并结合计算结果给出了单面受火的方钢管约束钢筋再生混凝土柱的耐火极限简化计算式，可为该类柱抗火设计提供参考。

Fire resistance of square steel tube confined reinforced recycled concrete column in one-surface fire

In order to study the fire resistance of square steel tube confined reinforced recycled concrete column in one-surface fire, the finite element model of square steel tube confined reinforced recycled concrete column in one-surface fire under the effect of ISO-834 standard fire was established using the finite element analysis software ABAQUS, and the temperature field and stress of the section were analyzed. The law of changes in the field was verified using existing tests. On this basis, the effects of substitution rate, concrete strength, load ratio, steel content, eccentricity ratio, load angle, reinforcement ratio, dimensions and steel strength on the fire resistance of the component were analyzed. The results demonstrate that the effect of load eccentricity and load angle on the fire resistance limit is more complex. When the load angle is 180 degrees, the load eccentricity ratio increases from 0.2 to 0.4, and the fire resistance limit increases by 11.2%. When the load eccentricity ratio is 0.8, the load angle increases from 0 to 90 degrees, and the fire resistance limit of the component is reduced by 32.2%. The load ratio and section size have obvious influence on the fire resistance limit. When the steel content is 5.33%, the load ratio increases from 0.4 to 0.5, and the fire resistance limit decreases by 37.1%. When the steel strength grade is Q345, the fire resistance limit of the member increases by 66.73% when the section size is increased from 200mm to 300mm. Based on the above-mentioned rules and combined with a large number of calculation results, a simplified calculation formula for the fire resistance of square steel tube confined reinforced recycled concrete column in one-surface fire was quantitatively given. It can provide reference for the fire-resistance design of square steel tube confined reinforced recycled concrete column in one-surface fire.