Incremental Launching Control Techniques for Wide Composite Girder Bridge with Complex Vertical Curves

The Fenghuangling Bridge in Liuzhou, Guangxi Province, is a continuous steel-concrete composite girder bridge with spans ( 96 + 124 + 3 X 130 + 90) m. The superstructure, measuring 46.6 m wide, consists of constant-depth single-cell steel trough girders that act compositely with the overlaid concrete slabs. The bridge is composed of three circular curved axes and two straight axes. The steel trough girders were incrementally launched, with a maximum launching distance of 130 m, and no temporary piers were added to assist the construction. The complex vertical curves of the bridge, long incremental launching distance, complicated construction procedures of concrete slabs and external prestressing tendons posed great challenges for the construction. To ensure the safety of the structure during construction, as well as the alignment and internal forces of the bridge after completion could meet the design requirements, the alignment, the launching nose needing crossing piers, and the concrete slab installation were all brought under control. During incremental launching, the geometric state transfer method was used to predict and control the installation alignment of the girder segments to ensure the completed alignment of the bridge. The displacement response of the end of the launching nose to the tensioning of the temporary stay cables as well as the ambient temperatures was analyzed. The launching nose was guided to cross the piers via tensioning temporary stays. The concrete slabs were placed following a modified Pilger process, to ensure the required stresses in the steel girders and concrete slabs and shorten the construction schedule. The measured alignment of the superstructure after completion meets the design requirements, and the completed bridge is sound. © 2023 Wuhan Bridge Research Institute. All rights reserved.