后结合预应力组合梁桥的混凝土预应力实效测试与分析

Field Test and Effect Analysis of Concrete Prestress for the Post-Combined Prestressing Composite Girder Bridge

摘要:

为了研究后结合预应力法在组合结构连续梁桥中的应用效果，并与常规预应力组合梁的预应力实施情况进行比较，基于换算截面法分别推导了后结合和常规结合连续组合梁桥的中支点截面应力计算公式，结合国内首座大跨度后结合预应力组合连续梁桥开展实桥受力性能测试，测量负弯矩区中支点截面在各施工工况中的应力状态。测量结果表明：后结合预应力法不会在钢梁中产生压应力，有效提升了预应力在混凝土中的施加效率，后结合法产生在混凝土中的预压应力是常规预应力法的1.3倍。计算分析表明，采用后结合预应力法在跨径70 m以下连续组合梁中可以实现混凝土桥面板为全预应力状态，在跨径110 m以下连续组合梁中可以实现混凝土不开裂的A类预应力状态。

关键词:钢混组合梁桥;后结合预应力法;负弯矩区;混凝土桥面板

Abstract:

In order to evaluate the application of the post-combined prestressing method in continuous composite bridge， and compare the post-combined prestressing method with the conventional pre-combined method， the formulas of section stress at the intermediate support from a post-combined and pre-combined composite bridge were derived based on the transformed section method. The field test was also conducted on the first large span post-combined continuous composite bridge constructed in China. The section stress at the intermediate support was measured during each construction stage. The test result shows that the post-combined method will not introduce compressive stress in the steel beam， which improves the efficiency of the prestressing the concrete deck. The concrete stress generated by the post-combined method is 1.3 times that of the concrete stress generated by the conventional prestressing method. The calculation that the post-combined method can achieve the full prestressing state of the concrete deck in the continuous composite bridge with a span less than 70 m， and the concrete deck without cracking can be realized in the continuous composite bridge with a span less than 110 m.

Key words:steel-concrete composite bridge;post-combined prestressing method;negative bending region;concrete deck