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

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