Abstract Summary
As a short bridge is subject to a high speed train traveling over it with (sub-)resonance speeds, the dynamic interactions between the supporting bridge and moving train plays an important role in estimating the resonance speeds of the bridge for its coupling effects may result in the bridge response reducing and further down-shift the (sub-)resonant speeds. However, the well-developed theoretical (sub-)resonant speed (= fD/n) with n=1,2,3… of a typical railway bridge is only related to the bridge frequency (f) and car length (D), but the train-bridge-interaction (TBI) effects were neglected. Such an overestimatio of resonance speeds may result in mistaking the train-induced reonance of the bridge in design stage. To predict the sub-resonance speed(s) of a short railway bridge that can take TBI effects into account, an equivalent modal mass method will be proposed so that the down-shifted frequency due to the presence of multiple train cars on the bridge can be accounted for. From numerical demonstrates, the proposed method can estimate the shifted resonant speeds and further explain the shifted-resonance phenomenon of short railway bridges under train passage.
