Wind-Rain-Induced Static And Dynamic Characteristics Of Long-Span Bridge Decks

Entering the 21st century, the construction of sea-crossing projects and isles connection projects all over the world promoted the development of longer-span bridges. Super-long-span bridge structures will suffer more complex loads, especially the extreme loads coupled by several different loads. Wind load and rain load coupling effect therein will be the first consideration for the structure analysis and design of super-long-span bridge structures. At present, researches on the structure analysis and design theory of long-span bridge structures have only used a uniform wind field or turbulent wind field, but the effect of rainfall has not yet been taken into account. In fact, strong wind, especially typhoon, is always accompanied with heavy rain in nature. The coupling interaction between strong wind and rainstorm is the main features for this kind of weather. The simultaneous wind-rain action causes an extreme load condition for the super-long-span bridge structures, which are built in regions frequently attacked by typhoons. When long-span bridge structures are in the environment of simultaneous wind and rain actions, it is not enough to do structural response analysis and design based on previous structure analysis and design theory of long-span bridge structures, which were established by considering single wind field environment. The reason lies in the existence of rain field and the coupling effect between rain and wind. Based on this, this paper analyzes and studies the static and dynamic characteristics of long-span bridge decks under the simultaneous wind and rain actions from the angle of theoretical analysis and wind tunnel experiments. Its main research contents are as follows:1. Three factors of wind-rain-induced static forces, namely, wind-rain-induced static three factors were proposed aiming at the phenomenon of simultaneous actions of wind and rain for long-span bridge decks, based on the theoretical analysis in static. The corresponding testing method was given. The wind-rain-induced static characteristics test was carried out by considering the static performance of a long-span bridge under the joint wind and rain fields, taking a separated twin-box bridge deck section model of a long-span bridge as the research object, utilizing the experimental system of simultaneous interactions of wind and rain built in the atmospheric boundary layer wind tunnel. The influence law of the effect of rainfall on wind-induced static effect of long-span bridge deck sections was obtained.2. For the wind-rain-induced flutter stability of long-span bridge decks, an experiment under simultaneous interactions of wind and rain was carried out utilizing the experimental system of simultaneous actions of wind and rain built in the atmospheric boundary layer wind tunnel. A separated twin-box girder long-span bridge was employed as the specimen. The flutter derivatives of this bridge subjected to joint wind and rain were obtained, and relevant critical flutter wind speeds were calculated by using a simplified flutter analysis method. Through comparing the flutter derivatives and the critical flutter wind speeds under different rainfall intensities, the flutter stability of long-span bridges influenced by rainfall was evaluated.3. For the wind-rain-induced vortex-induced vibration characteristic of large-span bridge decks, an experiment under simultaneous interactions of wind and rain was carried out utilizing the experimental system of simultaneous actions of wind and rain built in the atmospheric boundary layer wind tunnel. A separated twin-box girder section model and its corresponding closed form were employed as the specimens. The wind tunnel test was carried out in the uniform wind-rain field. Through analyzing the testing data, characteristic of vortex-induced vibration for the main girder in joint wind and rain fields was obtained. Finally a high-speed camera was used to observe the coupling characteristics between wind and rain and their impact effect on the bridge deck section.