中文摘要：

提出了2种新型双管翼缘钢-混凝土组合梁截面形式：钢梁上翼缘为圆形钢管混凝土、下翼缘为矩形钢管混凝土（DFCG-1）与钢梁上、下翼缘均为矩形钢管混凝土（DFCG-2）的管翼缘组合梁。为研究此2种双管翼缘组合梁的抗弯性能,对1根DFCG-1和1根DFCG-2进行了跨中双点对称加载试验,分析了试验梁的变形、应变变化规律。依据试验梁弹性、弹塑性状态下的实测受力性能,采用简化弹塑性理论及结合应力-应变协调的弹塑性理论推导了双管翼缘组合梁屈服弯矩、极限抗弯承载力的简化计算公式。研究结果表明：试验梁破坏时表现出明显的塑性弯曲破坏特征,其破坏过程可分为弹性、弹塑性与破坏3个阶段;加载过程中,试验梁未出现平面内与平面外整体失稳,且未发生局部弹性失稳破坏;梁端钢管与内填混凝土间无相对滑移,管翼缘与混凝土翼板间最大滑移小于1.3mm,钢混组合截面各部分协同工作性能较好;DFCG-1,DFCG-2的位移延性系数分别为3.68,4.53,体现出较好的延性性能;DFCG-1,DFCG-2在抗弯刚度、承载力、破坏形态等力学性能上总体表现基本一致,但当翼板混凝土因压溃而退出工作后,DFCG-1更低的腹板高度使其较DFCG-2具有更好的腹板屈曲稳定性;所提公式计算结果与试验值吻合较好,可用于双管翼缘组合梁抗弯承载性能计算分析。

英文摘要：

Two innovative types of the steel and concrete composite girder with flanges, namely, one tubular flange composite girder with a circular concrete-fill compression flange and a rectangular concrete-filled tube as the tension flange （DFCG-1） and the other tubular flange composite girder with rectangular concreteboth the compression and tension flanges of steel girder （DFCG-2）, were double tubular ed tube as the of steel girder filled tubes for proposed. To investigate the flexural behavior of these two composite girders with double tubular flanges, the flexural experiments for DFCG-1 and DFCG-2 were carried out using double-point symmetric loading method at mid-span, and the deformation and strain regulations of tested girders were analyzed. According to the characteristics of test girders in the elastic and elastic-plastic state, the simplified formulas of yield moment and ultimate flexural capacity for DFCGs were deduced based on the simplified plastic theory and the elasto-plastic theory satisfying the stress-strain compatibility relationship. The results show that all test girders dramatically fail in plastic flexural mode. The failure process can be divided into elastic stage, elasto-plastic stage and failure stage. In-plane and out-plane global instability and local elastic buckling are not emerged during the loading process. No relative slip is observed between steel tube and inner filled concrete at the end of test girders. The maximum slip of 1.3 mm appears between steel tube and concrete flange, and the test girders show excellent cooperative working ability. When concrete slab collapses, the displacement ductility coefficients are 3.68 for DFCG-1 and 4.53 for DFCG-2 respectively, showing better ductility. Besides, the two test girders behave similarly in the stiffness, strength, failure modes, and so on, but after the concrete slab crushed, DFCG-1 shows a better stability of shear buckling than DFCG-2 because of the lower web height. The analytical results are in good agreement with the experime