体外索钢箱-混凝土组合梁力学性能研究

对一种新型的体外索钢箱-混凝土组合梁与普通的钢箱-混凝土组合梁进行对比试验，研究这两种钢箱-混凝土组合梁受力过程中的应变分布、界面滑移、刚度、极限强度等力学性能的差异。试验证实，体外索钢箱-混凝土组合梁比普通的钢箱-混凝土组合梁的刚度提高54．15％，极限强度提高27．72％。由于体外索的作用，减少了钢箱-混凝土组合梁的脆性破坏程度，提高了结构的强度与刚度，使钢箱-混凝土组合梁的应变分布和增长更为合理。因此，体外索钢箱-混凝土组合梁具有更好的力学性能。试验表明，截面应变沿宽度方向呈非线性分布，剪力滞效应随荷载的增加而变化，并不是常量。研究还发现，体外索应力与混凝土翼板最大压应变有密切的关系。在试验研究基础上，建立了截面非线性分析模型和体外索钢箱-混凝土组合梁极限强度计算公式，计算的极限强度与试验结果符合很好，这为体外索钢箱-混凝土组合梁极限强度的理论分析和工程实际应用提供了有意义的参考和研究途径。

Study on mechanical properties of external cable steel box-concrete composite beams

The difference of strain distribution, interface slip, stiffness, ultimate strength and other mechanical properties between a new type of external cable steel-concrete composite beam and ordinary steel-concrete composite beam is studied. The test results show that the rigidity and ultimate strength of the steel box-concrete composite beam with external cable increase by 54.15% and 27.72% compared with the ordinary steel box-concrete composite beam. Due to the effect of external cable, the brittle damage degree of the steel box-concrete composite beam is reduced, the strength and stiffness of the structure are increased, and the strain distribution and growth of the steel box-concrete composite beam are more reasonable. Therefore, the composite beam with external cable steel box and concrete has better mechanical properties. The experimental results show that the strain distribution of the section is nonlinear along the width direction, and the shear lag effect changes with the increase of the load, but is not constant. It is also found that the external cable stress is closely related to the maximum compressive strain of the concrete wing slab. On the basis of the experimental research, the section nonlinear analysis model and the calculation formula of the ultimate strength of the external cable-steel box-concrete composite beam are established. The calculated ultimate strength is in good agreement with the experimental results, which provides a meaningful reference and research way for the theoretical analysis and practical application of the ultimate strength of the external cable-steel box-concrete composite beam.