The influence of rainfall on the static characteristics of bridge deck sections

The three influencing factors of windraininduced static forces were analyzed aiming at the phenomenon of simultaneous actions of wind and rain for longspan bridge decks, based on the analysis of static load on the bridge deck section. The test method of the increment of windraininduced static forces in joint wind and rain comparing to windinduced static forces in single wind is given. The windraininduced static characteristics test was carried out in the surroundings of simultaneous actions of wind and rain built in the atmospheric boundary layer wind tunnel, taking a twinseparated box girder as research object. The influencing rule of rainfall on the windinduced static forces of bridge deck sections was obtained. Experimental results display the effect of impact force of rain on the windinduced drag force of bridge deck sections is dominant in the large negative angle of attack of circumstances. The effect of change of flow field and water film on the surface of bridges on the windinduced drag force of bridge deck sections is dominant in the small negative and positive angle of attack of circumstances. The gravity of raindrops, impact force of rain, change of flow field and water film on the surface of bridges all have certain contribution on the windinduced lift force of bridge deck sections. The change of flow field and water film on the surface of bridges play the most important role on the windinduced pitching moment of bridge deck sections, followed by the gravity of raindrops, finally is the impact force of rain. The result shows that the effect of rainfall on the windinduced static forces of bridge deck sections is mainly depended on the change of flow field and water film on the surface of bridges.