中空夹层方钢管再生混凝土柱火灾后剩余承载力

为研究中空夹层方钢管再生混凝土柱火灾后剩余力学性能，运用有限元分析软件ABAQUS建立了ISO 834标准火灾作用后中空夹层方钢管再生混凝土柱的有限元模型，分析了截面温度场和应力场的变化规律。在此基础上分析了混凝土强度、钢材强度、计算长度、受火时间、空心率、混凝土取代率、偏心率等参数对构件火灾后剩余力学性能的影响；结合大量计算结果给出了中空夹层方钢管再生混凝土柱火灾后剩余承载力简化计算公式。结果表明:构件的火灾后剩余承载力随钢材强度和混凝土强度的增加而增加；构件火灾后剩余承载力随计算长度和受火时间的增加，总体呈降低趋势，当受火时间超过60 min时，构件火灾后剩余承载力急剧降低；空心率和混凝土取代率对构件火灾后剩余承载力影响较小，构件火灾后剩余承载力随空心率的增加而降低，随混凝土取代率的增加先增加后降低；构件火灾后剩余承载力随偏心率的增加而降低；所提公式计算精度良好，可为中空夹层方钢管再生混凝土柱抗火设计提供参考。

Residual Bearing Capacity of Hollow Sandwich Square Steel Tube Recycled Concrete Column After Fire

In order to study the residual mechanical properties of hollow sandwich square steel tube recycled concrete column after fire, the finite element model of hollow sandwich square steel tube recycled concrete column under ISO 834 standard fire action was established by using finite element analysis software ABAQUS. The variation of temperature field and stress field of cross section was analyzed after verification of relevant experiments. On the basis, the effects of concrete strength, steel strength, calculated length, fire time, hollow ratio, concrete substitution ratio and eccentricity on the residual mechanical properties of components after fire were analyzed. A simplified formula for calculating the residual bearing capacity of hollow sandwich square steel tube recycled concrete column after fire was given quantitatively based on a large number of calculation results. The results show that residual bearing capacity of components increases with the increase of steel strength and concrete strength after fire. The residual bearing capacity of components decreases with the increase of calculating length and fire time. When the fire time exceeds 60 min, the residual bearing capacity of components decreases sharply after fire. The hollow ratio and concrete substitution ratio have little influence on the residual bearing capacity of components after fire. The residual bearing capacity of components after fire decreases with the increase of hollow ratio, and increases first and then decreases with the increase of concrete substitution ratio. The residual bearing capacity of components decreases with the increase of eccentricity after fire. The calculation accuracy of the proposed formula is good, which can provide reference for fire resistance design of hollow sandwich square steel tube recycled concrete columns.