Abstract:
To address the construction control problem in the integral lifting of arch ribs for long-span steel tube arch bridges, proposed is an optimization method that considers the coupling effect of tower and of temporary horizontal tie bar positions. Taking the G75 Qinjiang Bridge of the Pinglu Canal crossing project on the "New Western Land-Sea Corridor" as a case study, a mechanical model for the construction process is developed using the OpenSeesPy open-source library. A mapping relationship between the temporary horizontal tie bar forces and the arch rib construction state is established via a modified influence matrix. Subsequently, an unconstrained optimization model is constructed using a first-order optimization method with a penalty function. This model iteratively solves for the optimal tower positions, for the temporary horizontal tie bar locations, and for their corresponding tensioning forces. The approach effectively controls the geometric deviation during the lifting process and ensures the final arch state meets design requirements. Research results indicate that after arch closure and cable relaxation, the maximum arch rib deformation is less than 4.4 mm, showing a deviation of less than 8% in internal force distribution compared to the single-stage support removal condition. The fact, that the arch rib deformation after lifting is significantly smaller than permissible regulatory values, validates the control accuracy of the method proposed for the integral lifting construction of large-span arch bridges, providing a reliable theoretical foundation and practical reference for similar projects.