Mechanical Behavior Control Method of Prefabrication and Cantilever Assembly for Wide Steel- Ultra High Performance Concrete Composite Girder of Kilometer-Span Cable-Stayed Bridge

To optimize the stress of wide steel-ultra high performance concrete (UHPC) composite girders in super-long-span cable-stayed bridges during construction, this study proposes a mechanical behavior control method for the prefabrication and cantilever assembly of the composite girder. First, a finite element model of a cable-stayed bridge with a main span of 1,160 m is established, and the stress and deformation of composite girder segments during prefabrication and assembly are analyzed. Based on the characteristics of composite girder prefabrication, this study proposes a method for applying transverse prestress to the bridge deck during prefabrication of composite girders, theoretically derives this method, and investigates the impact of varying inverted arch degrees on transverse prestress through the model. Subsequently, the deformation behavior of the cross-section of the wide steel-UHPC composite girder during the cantilever assembly is analyzed, and the hanging cable-unloading matching method is proposed, which effectively controls the relative deformation of the girder during installation. The findings of this study demonstrate that the comprehensive methodology proposed in this paper ensures that the bridge deck maintains an adequate compressive stress reserve throughout the entire segment prefabrication process, and the deformation of adjacent segments remains relatively uniform during cantilever assembly, thus realizing high-quality prefabrication and high-precision assembly of composite girders.