Progressive bridge collapse analysis under both scour and floods by coupling simulation in structural and hydraulic fields. Part Ⅰ: Numerical solver

Abstract

Hydraulic bridge failures have become the greatest threat to the structural safety of bridges. Combined numerical simulations are rare due to the high computational cost of structural nonlinear finite element analysis (NLFEA) and computing fluid dynamics (CFD). Structural analysis and design for extreme hydrological hazards are challenging due to complicated hydrodynamics-soil-structure interactions. This paper proposes a numerical solver to simulate hydraulic bridge failures through coupling simulations. The solver applies hydrodynamic load and updates scour boundary in a structural model by utilizing a scatter linear interpolation method based on the Delaunay triangulation algorithm in each loop solution. Then, a simplified sediment stress model considering external forces in the vertical plane and a complex model with an arbitrary slope in three-dimensional coordinates are introduced into the basic incipient motion model of sediment, resulting in a more realistic stress state of sediment. Finally, the numerical solver is adapted to provide an accessible method to investigate the influence of such a modified model on the scour process and structure response. Meanwhile, the validation of this numerical solver is conducted in a companion paper based on the comparison between the numerical result of the hybrid model and the field data.