Design Optimization of Temporary Cross Bracing for Long-Span Cable-Stayed Bridge Pylons Using the Minimum Bending Energy Method

Abstract

The minimum bending energy method is currently used on cable towers of A-frame cable-stayed bridges constructed using the segmental method. In practical applications, the calculation results derived from this method serve merely as guidelines; the precise magnitude of the jacking force must be adjusted based on actual conditions. Furthermore, the applicability of this method to bridge towers employing alternative construction techniques or geometries warrants further investigation. The minimum bending energy method was introduced to determine and validate the jacking force of the temporary cross braces, while a self-developed Bridge Design and Construction Management System (BDCMS) program was used to conduct finite element analysis of the pylon in an ongoing long-span cable-stayed bridge project. Taking into account structural stress and pylon alignment, a comprehensive optimization strategy for the temporary cross braces was implemented. The results suggest that optimizing temporary cross braces using the minimum bending energy method is applicable, with the jacking force magnitude influenced by both the cross-brace position and the pylon’s inclination angle; under the optimized temporary cross-brace strategy, the stress difference following brace removal decreased from 6.2 MPa to 5.3 MPa, while the maximum stress difference after bridge completion was reduced from 5.7 MPa to 5.3 MPa. This ensures that the structural stress of the pylon during both the construction and operational stages complies with the specification requirements, providing valuable guidance for optimizing the temporary cross braces of A-frame pylons constructed in segments.