The Practice of Demolishing a Truss-Combined Arch Bridge

The demolition of the severely deteriorated 150-m main span Huayudong truss-combined arch bridge in China presented significant challenges. Because of its location over a primary water source, a nonexplosive approach was needed. This paper details a reconstruction-before-demolition methodology whereby the newly constructed basket-handle concrete-filled steel tubular (CFST) arch structure served dual functions as permanent infrastructure and temporary support structure for dismantling the old bridge. The demolition was guided by the principles of minimizing the internal forces of the main arch and enhancing protective safety measures during the arch-severing process. Through systematic implementation of internal force management strategies comprising three-phase weight reduction (deck removal, chord cutting, and center box dismantling) and two-stage cable tensioning, the axial force at severance section was effectively reduced. The developed safety control system integrated four key components: (1) double vertical web anchoring with threaded bars, (2) hydraulic jack counterforce system, (3) deformation restraint brackets, and (4) phased cutting protocol featuring concave-convex and Z-shaped seam profiles. The successful onsite demolition was characterized by negligible impact or vibration during arch severing, with monitored deformations and cable forces largely corroborating theoretical calculations. The demolition strategies and specific technical measures presented in this paper can serve as a reference for the demolition of other arch bridges.