高性能耐火耐候钢-混凝土简支组合梁抗火性能的数值分析

Numerical Analysis on Fire Resistance of High-Performance Fire-Resistant and Weathering Steel-Concrete Composite Beams

随着钢材冶炼技术发展,采用耐火耐候钢、闭口压型钢板提升钢-混凝土组合梁抗火性能成为钢结构抗火设计新方法。采用ABAQUS有限元软件,选取合理的材料高温热-力学性能参数和计算策略,并通过数值计算结果与钢-混凝土组合梁抗火性能试验结果对比,验证了数值模型的准确性与可靠性。以此为基准模型,改变材料热膨胀系数、荷载比、钢梁截面尺寸等参数,总结得出钢材热膨胀系数、钢梁高度、楼板厚度、荷载比对耐火耐候钢-混凝土简支组合梁耐火极限影响较大的结论,并基于参数化计算,分析数值模型计算组合梁正截面抗弯承载力与GB 51249—2017《建筑钢结构防火技术规范》中承载力法计算结果的差异,提出了标准升温下该型组合梁修正的承载力计算方法。

With the development of steel-smelting technology,using fire-resistant and weathering steel and encased profiled steel sheets to promote the fire resistance of composite beams has become a new solution for steel structure fire design.Adopting appropriate thermo-mechanical material properties and calculating strategies,the accuracy and reliability of the numerical model were verified by comparing the results calculated in ABAQUS platform based on the experimental data from fire resistance tests of steel-concrete composite beams.Based on the proposed benchmark model,adopting different material thermal expansion coefficients,load ratios and steel beam sizes,conclusions were drawn that the thermal expansion coefficient,steel beam height,thickness of the composite slab and load ratio had a greater influence on the fire resistance of simply supported fire-resistant and weathering steel-concrete composite beams.By comparing the results calculated by the numerical model with those calculated by the bearing capacity method according to Code for fire safety of steel structures in buildings(GB 51249-2017),a modified bearing capacity method was proposed for the composite beams.