新旧钢筋混凝土梁横向拼接的收缩徐变效应分析

Analysis of shrinkage and creep effects in widening reinforced concrete girder

为了研究旧桥横向拓宽时混凝土梁的收缩徐变效应,采用错位法对新、旧梁横向拼接后收缩徐变产生的应力重分布进行了分析,在不考虑重力情况下推导了拼接后新、旧梁横截面上的纵向应力及拼接处的纵向剪应力计算公式.以空心板梁为例,分析了由收缩徐变效应引起的新、旧梁上的纵向应力,比较了不同配筋率对板中纵向应力的影响.分析结果表明,新梁中的纵向拉应力可能会引起新梁横向开裂,纵向配筋率对混凝土梁的受力影响较大,而新旧梁拼接处的剪应力则较小.

To investigate the shrinkage and creep effects in transversally widened old bridges, the stress redistribution due to long term shrinkage and creep was analyzed using lack-of-fit approach after old girders were widened with new girders. Furthermore, formulae of vertical stress at cross sec- tion and shear stress at contact surface were presented without consideration of gravity. Taking hollow slabs as examples, vertical stress at the slabs due to shrinkage and creep was calculated and vertical stresses under influence of different reinforcement ratios were compared. The results show that vertical tensile stress would probably cause transversal cracks in new girders, vertical reinforcement ratios make remarkable effects on stress of concrete girders, and the shear stress produced by shrinkage and creep effects is small.