Air vents in bridge decks are considered one potential measure for mitigating risk of damage to coastal bridges caused by extreme storm surge because they may reduce hydrodynamic uplift loads significantly. This paper presents a systematic, two-dimensional, numerical study on physical phenomena and hydrodynamic loads involved during the impact of solitary waves on a bridge deck with vents. The effects of the opening size of vents and other prominent factors, including submergence of the deck, wave height, water depth, and number of girders, on hydrodynamic loads were investigated through the numerical study. It was found that, when the deck was submerged initially, the vertical loads on the bridge deck achieved their maximum values at a certain opening size of vents, and their magnitudes could be significantly higher than on a deck without vents. Formulas as functions of these factors were developed based on the computational results to estimate efficiency of air vents to reduce hydrodynamic loads on bridge decks.

In this paper, a numerical wave-loading model using the dynamic-mesh updating technique is combined with a nonlinear finite-element (FE) model to investigate the behavior of costal bridge superstructures under solitary waves. The numerical model has been tested by comparing it with laboratory experiments performed at Oregon State University. It is proven that the proposed model is reliable for predicting the bridge–wave interaction. Full-scale numerical experiments are then conducted to discuss the effect of vertical flexibility on connection forces. In this study, a typical value of horizontal restraint has been assigned to each bridge deck, and the vertical flexibility is introduced by allowing the bridge deck to rotate about the onshore side. The results show that a higher extent of deck rotation movement is accompanied with larger horizontal resultant forces. Also, the pattern of vertical resultant is significantly influenced, whereas the peak value does not change much. Moreover, the general characteristics of the relationship between the vertical resultant force and the overturning moment are discussed in detail for a vertically fixed deck, and they are represented by interaction diagrams. The direction of the overturning moment is distinguished. The significance of a negative overturning moment is revealed. At the end of the paper, an empirical model for predicting the interaction diagrams is proposed and tested.