Reliability-Based Design Optimization of a River Bridge Considering Uncertainty in Scours

Abstract

Safety assessments of river bridges have attracted a great deal of attention from researchers. Regardless of whether a bridge is being constructed or retrofitted, an integrated analysis of many factors, such as hydraulic conditions, geological conditions, and structural strength, is necessary. A three-dimensional finite-element model is used here to perform structural analysis. The uncertainty in important parameters (such as water level, water flow rate, scouring depth, and the N value of the standard penetration test) was considered via a reliability analysis. A parameterized bridge model was established to perform the iterative calculations required for the optimization and reliability analysis, in which the preprocessing, solution, and postprocessing were all performed automatically to facilitate a reliability-based optimization. To reduce the number of calculations, a surrogate model was adopted, in which the reliability analysis uses the first-order second-moment method and the optimization uses the particle swarm optimization method. A numerical example (the Dongshi Bridge) is given to demonstrate the methodologies proposed in the study.