二次预应力梁的徐变和承载力试验研究

在中小跨径的预应力梁式桥中,经常出现张拉过程中直梁反拱过大,弯梁横移,刚构桥立柱开裂等问题,这些都是由于预应力附加内力过大引起的。为了解决此类问题,提出二次预应力新型桥梁结构的概念。通过对这种结构与常规预应力结构的比较分析和10 m跨径的二次预应力梁和常规预应力梁的对比试验,证明二次预应力技术在低高度梁中的应用,可以大大改善低高度梁在施工和长期使用过程中的受力和变形性能。同时推导了二次预应力结构任意时刻的徐变内力计算公式,并验证了二次预应力结构的承载能力。指出二次预应力技术在中小跨径预应力梁式桥中有着广阔的应用前景。

An experimental study on the creep behavior and bearing capacity of twice prestressed concrete beams

Due to the large additional stress from prestressing,many serious problems,such as the camber of a straight bridge beam being too large,curved beam drifting in its transverse direction,and columns of rigid beam bridge cracking frequently,may occur in the pre-stress tensioning process of medium or short span prestressed beam bridges.To deal with these problems,a new type of twice prestressed beam is herein proposed.Through theoretical and experimental comparisons between this new structure and the traditional prestressed concrete structure,it is found that the application of twice prestressing can significantly improve the mechanical performance of the beam in the construction process and long-term use.A theoretical solution is derived for the creep strain and internal force due to twice prestressing,and the bearing capacity of the structure is validated.