预应力混凝土简支梁徐变应力重分布的研究

The Research on Redistribution of Stress Due to Creep of Prestressed Concrete Built-up Beam

基于平截面变形、徐变与应力之间符合线性关系和徐变特性与加载龄期之间的关系符合老化理论等假定 ,探讨了不同龄期混凝土组合梁的徐变应力重分布问题 ,研究了分片预制桥位设现浇接缝的预应力混凝土简支T梁徐变应力重分布的计算理论和计算方法 ,推导了徐变应力重分布计算公式。组合结构由于先、后浇注的混凝土存在明显的龄期差和应力差 ,徐变将产生明显的应力重分布 ,应力重分布效应取决于先、后浇注的混凝土的龄期差和应力差。秦沈客运专线跨度 16m简支T梁徐变应力重分布测试表明 ,对先期浇注的混凝土部分 ,重分布应力大约占总恒载应力的 10 %～ 2 0 % ,而对后期浇注的混凝土部分 ,影响比值更大 ,甚至有可能使应力反号 。

Based on the assumption of linear relationship between section deformation, creep and stress and the theory of linear creep, the redistribution of creep stress of concrete structure with different loading ages are discussed. The calculation method and theories of creep stress redistribution are studied, and the computing formulas are developed. Due to the loading ages and stress magnitudes between the pre poured concrete and the post poured concrete, the creep stress redistribution is caused in prestressed concrete built up beams. The values of the creep stress redistribution depend on the loading ages and stress magnitudes. The redistribution of creep stress of the T beam of span 16 m at the Qinshen dedicated passenger line is about 10%-20% of the dead load stress for pre poured concrete, the influence on the post poured concrete is lager, and the direction of the stress can be reversed sometimes. The problem of the redistribution of creep stress for the built up beam should be taken care of.