Hydraulic Loads on Bridges during Floods: Comparative Assessment Based on Code Provisions

Flood hazards are becoming increasingly prevalent in several countries due to multiple reasons including global climate change. Bridge failure statistics indicate that over the last couple of decades, flood-related issues such as scour, hydrodynamic forces, and debris forces have caused the maximum number of bridge failure cases worldwide in comparison with other natural hazards. Such observations clearly demonstrate the need for consistent code provisions among different codes to design highway river-crossing bridges against the growing demand from flowing water during floods. The current study performs a comprehensive review of six international bridge design codes that provide guidelines to calculate flood-induced forces for design of bridges against flood. Following these provisions, flood loads on various components of two bridges with different geometric configurations and material properties are estimated under a number of flood cases. Finite-element (FE) models of the bridges are developed to analyze them for estimated flood loads. The outcomes revealed that obtained bridge response following these six codes varied over a wide range. A comparative assessment among these response values demonstrated the disparity of these code provisions for flood design of bridges.