圆管翼缘钢-混凝土新型组合梁极限抗弯承载力与延性

为研究圆管翼缘组合梁的抗弯性能, 进行了3根圆管翼缘组合梁静力加载抗弯破坏性试验, 分析了试验梁的抗弯破坏过程与破坏特征; 考虑混凝土损伤塑性本构及栓钉滑移与断裂, 建立了圆管翼缘组合梁非线性数值模型, 基于试验结果分析了数值模型的适用性; 以钢梁下翼缘宽度、混凝土翼板厚度与圆管管径为主要结构参数, 计算了48根正交设计的圆管翼缘数值模型组合梁的力学性能; 依据试验梁与数值模型梁的抗弯受力性能, 提出了基于简化塑性理论的圆管翼缘组合梁极限抗弯承载力计算公式; 应用数值模型梁位移延性系数计算结果, 回归得到了圆管翼缘组合梁位移延性系数计算公式。计算结果表明: 数值模型组合梁与试验梁承载力比值为0.99~1.03, 挠度比值为0.87~1.09, 因此, 弯矩-挠度计算曲线与试验曲线吻合良好, 可采用数值模型组合梁准确模拟圆管翼缘组合梁的抗弯全过程受力行为; 圆管翼缘组合梁极限抗弯承载力随钢梁下翼缘宽度、混凝土翼板厚度的增大而增大, 随圆管管径的改变变化较小, 位移延性系数随混凝土翼板厚度与圆管管径平方的增大呈线性增大, 随钢梁下翼缘宽度的增大呈线性减小; 不同塑性发展程度的各类模型梁位移延性系数为3.16~7.19, 体现了较好的延性; 采用极限抗弯承载力简化计算公式与圆管翼缘数值模型组合梁计算的极限抗弯承载力比值为0.91~1.09, 平均比值为0.98, 因此, 公式计算结果准确; 为使圆管翼缘组合梁具有一定延性, 建议位移延性系数大于3.5。 

Ultimate flexural strength and ductility of steel and concrete composite girder with circle tubular flange

In order to investigate the flexural performance of steel and concrete composite girders with circle tubular flange, the flexural failure tests of three composite girders with circle tubular flange were carried out by static loading, and the failure processes and failure characteristics of test girders were obtained.Based on considering the damage plasticity constitution of concrete, the slippages and fractures of studs, the nonlinear finite element models of composite girders wereconducted and validated by using experimental results.The width of lower flange of steel girder, the thickness of concrete slab and the diameter of tube were taken as main structural parameters, and the mechanical properties of 48 numerical model composite girders with circle tubular flange based on orthogonal design were calculated.According to the flexural behaviors of test girders and numerical model girders, the ultimate flexural bearing capacity formulas of composite girders with circle tubular flange were established based on the simplified plastic theory.By the numerical calculation results regression, the empirical expression of displacement ductile coefficient for composite girders was proposed.Computation result shows that the strength and deflection ratios of the numerical models to the test girders are 0.99-1.03 and 0.87-1.09, separately, so the moment-deflection computation curves are in good agreement with the experimental curves, which demonstrates that the whole processes of flexural behaviors for composite girders with circle tubular flange can be simulated accurately by using the numerical models.The ultimate flexural strength of composite girder with circle tubular flange increases with the increase of lower flange width of steel girder and the thickness of concrete slab, and changes little with the diameter of tube.The displacement ductile coefficient increases linearly with the increase of thickness of concrete slab and diameter square of tube, whereas reduces linearly with the increase of lower flange width of steel girder.For the model girders with different plasticity statuses, the displacement ductile coefficients are 3.16-7.19, which indicates good ductility.The ratios of ultimate flexural strengths computed by using the proposed simplified formulas and the numerical model composite girders are 0.91-1.09, and the average ratio is 0.98, so the computation result by using the formulas is accurate.To ensure the appropriate ductility of composite girder with circle tubular flange, it is suggested that the displacement ductile coefficient is greater than 3.5.