Dynamic response analysis of widening bridge due to moving vehicles

Rapid economic growth has led to a sharp increase in the highway traffic volume in China, and then more and more bridges widening projects are carried out to reply the situation. When a bridge is widened by constructing a new deck and casting a concrete stitch between the existing deck and the new deck, it is often required to maintain traffic without interruption and as a result the curing concrete stitch would be subjected to traffic induced vibration. The possible damaging effects of traffic vibration on curing concrete stitch have attracted concern from researchers and engineers. Therefore, it is very meaningful for the widening bridges to propose a detailed traffic restrictions or mitigation measures to avoid the adverse effect on the curing concrete stitch. Based on theoretical and experimental research results for concrete stitch of widening bridge, the vibration response threshold value causing crack damage induced by moving traffic load can be determined. The critical index of dynamic response value for a widening bridge is proposed, and its theoretical derivation process is explained in detail. Taking several typical PC simple supported T girder bridges as examples, the dynamic response of widening bridges under various vehicles loading cases are computed by the vehicle and bridge coupled vibration analyses program developed by authors. Some typical trucks and tested data for highway in China are applied on the research. Based on the analysis result, some advices about traffic control measures including limiting load, speed limit and lane limit etc. are presented to reduce or avoid the disadvantage influence of traffic vibration on curing concrete stitch for widening bridges. In addition, the reasonable construction technology is put forward, which provides a reference for the traffic control during constructing widening bridges.