Integrated analysis of the performance of pile-supported bridges under scoured conditions

Evaluation of scour effects on bridge performance helps predict the safety of bridges under critical scoured conditions, and as a result, may help prevent unnecessary losses. However, very few studies have been conducted on scour evaluation involving an integrated analysis of interactions between water, soils, pile foundations, and bridge structures. In this study, integrated analyses were conducted based on the following procedure: (1) nonlinear soil-structure interactions were considered for foundation analyses; (2) superstructure analyses were conducted by considering a bridge model under design flood conditions; and (3) integration of foundation and superstructure analyses was achieved based on iterative calculations of the stiffness matrices between the two models. The integrated analysis technique described in this paper enables bridge engineers to model the substructure and superstructure elements separately using software well-suited for the respective analyses, and to link the separate results using an iterative approach, forming a complete integrated analysis. Bridge 45 was selected as a case study to evaluate scour performance using the developed integrated analysis technique. Results show that scour increased lateral deflections of pile caps in an exponential manner. Greater lateral load was supported by the abutments as scour proceeded, while the resistance of pile foundations to lateral loads decreased at interior piers. Scour resulted in higher shear force and bending moment exerting on the pile foundation, and consequently increased the possibility of the failure of piles.