熊谷 宏之 (Hiroyuki KUMAGAI)
After the collapse of the I-35W Highway Bridge in Minneapolis, Minnesota in 2007, the importance of redundancy of bridges has been recognized. Although the multi-girder bridges are generally classified as redundant structure, it is not trivial which member contributes the redundancy of overall structure. As for composite girder bridges, RC deck and bracing systems are found to be effective in distributing the load after failure of the steel girder. However, for non-composite girder bridges, the contribution of RC deck is not clear since the composite action between deck and main girders has not been clarified under the situation that the bridge is subjected to the load beyond service load level. This study focuses on crossbeams and sway bracings of non-composite multi-girder bridges, and has evaluated the contribution to redundancy of these members through a series of nonlinear finite element analyses. As a result, cross beams and sway bracings are found to be alternate load path when the bridge has severe damage and to contribute the redundancy of the bridge.
Key Words : non-composite multi-girder bridge, redundancy, nonlinear finite element analysis, bracing systems