钢-混凝土箱型组合斜拉桥主梁混凝土收缩徐变分析

Shrinkage and Creep Analysis of the Concrete Girder on Composite Box Girder of Cable-stayed Bridge

组合梁斜拉桥兼有混凝土和钢结构的优点,但作为两种材料的结合体,混凝土收缩徐变会引起组合截面的应力重分配,可能促使混凝土裂缝的提前出现或加速裂缝的扩展,从而降低结构的受力性能和耐久性。采用有限元方法分析了混凝土收缩徐变对组合梁斜拉桥主梁应力重分布的影响,并对混凝土的加载龄期的影响进行了参数分析。计算结果表明:混凝土加载龄期越早,组合截面的应力重分布越明显;混凝土收缩徐变对混凝土桥面板的应力影响不大,但对钢梁应力影响较为显著,钢梁的应力增量达到钢材容许应力的30%左右。

Steel-concrete composite cable-stayed bridge has both the advantages of the concrete and the steel structures.As a combination of the material of concrete and steel ,the stress in concrete slab and steel girder will redistribute due to the shrinkage and creep of the concrete slab.These may cause the cracking of the concrete slab,and affect the mechanical behavior and durability of the structure.In view of these,the influence of shrinkage and creep on stress redistribution in composite cable-stayed bridge was analyzed,and a parametric analysis was conducted on different ages of concrete.The study results show that the earlier the loading age of concrete,the more prominent stress redistributions of composite sections.And the concrete shrinkage and creep have little effect on concrete deck but extraordinary effect on steel girder.The stress in steel girder can increase by 30% of the allowable stress.