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梁桁体系组合梁是一种新型钢-混凝土组合结构,通过对其结构的静力试验研究,分析了其沿截面高度纵向应变、混凝土翼板纵向应变、钢梁腹板应变、腹杆轴向应变随荷载的发展变化及跨中截面挠度变化规律和破坏机理。试验结果表明:组合梁从开始受荷到最终破坏整个过程经历弹性、弹塑性及破坏3个受力阶段,其破坏模式为典型的弯曲破坏;混凝土顶板剪力滞效应较明显,沿截面高度纵向应变发展仍符合平截面假定,在纯弯段内中和轴有明显上移趋势,桁架腹杆为压弯杆件或拉弯杆件;屈服荷载时挠跨比为1/418,极限荷载时挠跨比达到1/54,整体上体现出其具有良好的变形和延性能力。采用ABAQUS软件对与试验梁同尺寸的模型进行有限元分析,验证了试验结果的正确性及有限元模型的合理性;对比分析无倾斜桁架的同尺寸模型,得到梁桁体系组合梁极限承载力相对于无倾斜桁架组合梁提高了20%左右。
The beam-girder system composite beam is a new type of steel-concrete composite structure. Through the static test of the structure, the longitudinal strain of the cross-section, the longitudinal strain of the concrete wing, the web strain of the steel beam, Strain changes with the development of load and the variation of cross-section deflection and failure mechanism. The test results show that the composite beam undergoes elastic, elasto-plasticity and failure three stages of stress from the beginning to the final failure. The failure mode is typical bending failure. The shear lag effect of concrete roof is more obvious, Strain development is still in line with the assumption of flat section, the neutral axis in the pure bending section has a clear upward trend, the web of the truss is a bent bar or a bent bar; when the yield load is flexural-span ratio 1/418, the ultimate load Flexible to span ratio of 1/54, on the whole reflects its good deformation and ductility. The ABAQUS software is used to analyze the model with the same size of the test beam, which verifies the correctness of the test results and the rationality of the finite element model. By comparing and analyzing the same-size model without inclined truss, the ultimate bearing capacity of the composite beam with the beam-truss system Compared with non-inclined truss composite beam increased by about 20%.