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。

Mechanical performance of steel-concrete composite box beams with external tendons

A new type of steel-concrete composite box beam with external tendons is proposed,and experimentally compared with common steel-concrete composite box beams,to determine the difference in the mechanical performance of steel-concrete composite box beams with and without external tendons,such as strain distribution,interface slip,stiffness and ultimate strength,etc.The experiment results prove that the stiffness and the ultimate strength of the steel-concrete composite box beam are increased by 54.15 % and 27.72 %,respectively,through using external tendons.As a result of the external tendons,the degree of brittle failure of the steel-concrete composite box beam is reduced,the structural strength and stiffness is improved,and the distribution and increment of strains in the sections are more rational,indicating a better mechanical performance.The study demonstrates that the section strain along the width is nonlinearly distributed and that the effect of the shear lag is not constant and changes with the increment of the load.It is also found that there is a close relationship between the stress in external tendon and the maximum compressive strain of the concrete flange slab.Based on the experiment results,a nonlinear analysis model and the calculation equations of the ultimate strength of steel-concrete composite box beams with external tendons are established.There is good agreement between the calculated and experimentally measured ultimate strength.