Study of wave forces acting on the box-girder superstructure of coastal bridges in the submerged condition based on potential flow theory

Bo Huang,Bing Zhu,Jiawei Zhang,Xiaolu Cui,Qingyang Ren

doi:10.1186/s43251-020-00018-3

Abstract

The box-girder superstructure of coastal bridges is vulnerable to wave-induced damage in the case of small clearances. The analytical method for estimating the wave forces on the box-girder superstructure of coastal bridges is proposed based on the potential flow theory in this paper. The two-dimension problem of the box-girder superstructure under the wave action is defined with some necessary simplifications first. Then, the analytical solutions are solved by the eigenfunction matching method, and the wave force on the submerged box-girder superstructure is calculated using the Bernoulli principle. After validating the accuracy of the proposed method by previous calculations and the experimental test, the influences of the girder type and structural configuration on the wave forces of submerged box-girder are conducted using the proposed analytical method. The results show that the girder type has a significant effect on the wave forces of the submerged superstructure, and the influence of various structural parameters should be considered comprehensively in the structural safety design under wave actions. The results of the present study can provide a useful reference for the estimation of wave forces and the structural design of the box-girder superstructure of coastal bridges.

Highlights

With the continuous development of coastal traffic engineering and the frequent occurrence of marine disasters in recent years, the wave force has become the control load of coastal bridges
The box-girder superstructure widely used in the long-span coastal bridges is quite different from the T-type superstructure in structure type, and the flow field and the wave forces for these two superstructures will be different under the action of extreme waves
Researches on the wave forces of box-girder superstructures have found that the calculation methods and empirical formulas applicable to the extreme wave forces on T-girder superstructures cannot be directly applied to the calculation of extreme wave forces on box-girder superstructures

Summary

Introduction

With the continuous development of coastal traffic engineering and the frequent occurrence of marine disasters in recent years, the wave force has become the control load of coastal bridges. The wave-current interactions (Qu et al 2018; Huang et al 2018b), the effect of inclinations of the deck (Xu and Cai 2014; Motley et al 2015), the effect of submersion depth (Huang et al 2019a; Qu et al 2020) and the accuracy of particle finite element method in simulating the wave forces on bridge superstructures (Zhu et al 2018) were comprehensively studied using numerical methods Both experimental tests and numerical calculations require the necessary test site or large computing equipment, and the professional foundation and operational experience of relevant personnel are needed. Based on the experimental tests of wave forces on the box-girder superstructure and the empirical equation proposed by Xu et al (2016b), Huang et al (2018a) took the blocking effect of box-girder during the wave-bridge interactions into consideration and proposed an empirical method to estimate the maximum wave forces on box-girder. The influences of the girder type and structural configuration on the wave forces of the box-girder superstructures are conducted using the proposed method

Mathematical formulation

Results and discussion

Conclusions