Study On Equivalent Wind Load Of Long-Span Railway Continuous Rigid-Frame Bridge

When Long-Span Continuous Rigid-frame Bridge was built, it has big stiffness and good wind resistance. Influenced by the method of construction, in the stage of longest cantilever construction, the stiffness of bridge will be smaller than when it was completely built and the wind causes the buffeting response of the bridge. Too big buffeting response will influence the safety and common construction of the bridge. So the longest cantilever construction condition is the most unfavorable condition for wind resistance. And the wind load calculation in the longest cantilever construction condition has been the critical considered factor in bridge design.Equivalent wind load research in the bridge wind resistance researching area is relatively few, and the study of equivalent wind loads of continuous rigid frame bridge at longest cantilever condition is even less. This paper will study the equivalent wind loads of continuous rigid frame bridge at the longest cantilever state, based on the existing theory of equivalent wind loads and take the Wulongjiang bridge and the Beidongkou bridge as the research objects. The research of the simplified method of equivalent wind loads of continuous rigid frame bridge in this paper has the following main steps:first, we use the finite element software ANSYS to analysis the dynamic characteristics of the objects in different construction conditions. Then use the section modal wind tunnel experiment and the numerical calculation method to obtain the static load coefficients of the girder and bridge pier. The equivalent wind loads conclude three parts:average wind load, background wind load and inertial wind load. Different bridge responses (such as the displacement of the end of the cantilever, the moment of the cantilever and the moment of the bridge pier) correspond to different influence functions and vibration mode functions. Based on this, we researched the simplified method of the equivalent wind load of girder and pier, intend to obtain some simplified calculation formulas that can be used in the practical engineering and then used these formulas to calculate the different responses in the longest cantilever condition. To verify the correctness of these formulas, the research use the simplified calculation result compare with the LRC method result, standard method plus inertial wind load result, then we take error analysis, to get the scope of application and the degree of accuracy of the simplified calculation formulas.