组合连续梁桥收缩徐变与滑移效应的影响分析

Analysis on Influence of Shrinkage Creep and Slip Effect on Composite Continuous Beam Bridge

钢混组合梁桥由于其自重轻,跨越能力大的特点,近年来被逐步应用到大跨径连续梁桥上,发挥了两种材料结合的优势,扩展了连续梁桥的跨越能力。由于两种材料的差异性,在组合后受收缩徐变效应的影响,会导致结构内力重分布、产生附加变形。采用柔性连接件的组合梁在其结合面上会产生滑移,进一步增加附加变形。对于大跨径组合梁桥,其收缩徐变效应和滑移效应不容忽视,但影响程度和规律仍然不明确。以港珠澳大桥大跨径组合梁连续梁桥为背景,分析大跨径连续梁在有滑移时和收缩徐变效应下的影响。结果表明,在混凝土板收缩徐变作用下,有滑移时会导致位移增量和应力增量变大;置梁时间越长,主梁挠度越小,第1个月的置梁对挠度影响最为明显;收缩徐变使混凝土板的压应力减小,在成桥后期,中支点附近的混凝土板将出现拉应力;收缩徐变使钢梁顶的压应力增加,钢梁底的拉应力减小。

Due to the characteristics of light weight and large span,the steel-concrete composite beam bridge,which has the advantages of 2 kinds of material and extends the span capacity of continuous beam bridge,has been applied to the long-span continuous girder bridge in recent years. Because of the difference of the 2 kinds of material,the effect of shrinkage creep after assembly will cause the redistribution of internal forces and additional deformation. The composite beam with flexible joint will slip on the joint surface,and further increase the additional deformation. For long span composite girder bridge,the shrinkage creep effect and the slip effect should not be ignored. However,the degree and law of influence are still not clear. Taking a long span composite continuous beam bridge of Hong Kong-Zhuhai-Macao Bridge as the background,the influence of the shrinkage creep effect on long span continuous beam when there is slip is analyzed. The result shows that(1) under the action of shrinkage creep of concrete slab,the increments of displacement and stress will become larger caused by sliding;(2) the longer the beam storage time,the smaller the deflection of the girder,and the most obvious effect on deflection is first month;(3) shrinkage creep makes the compressive stress of concrete slab decrease,and in the later completion stage,the tensile stress will appear in the concrete slab near the center support;(4) shrinkage creep will increase the compressive stress at the top of steel beam,and decrease the tensile stress at the bottom of steel beam.