Evaluation of Proper Level of the Longitudinal Prestress for the Precast Deck System of Railway Bridges

철도교용 프리캐스트 바닥판의 적정한 종방향 프리스트레스 수준의 산정

Precast concrete deck has many advantages comparing with the in-situ concrete deck, and has been successfully applied to replacement of the deteriorated decks and to the newly constructed highway bridges in domestic region. In order to apply the precast decks into the railway bridges, however, differences of the load characteristics between the highway and the railway should be properly taken into account including the train load, longitudinal force of the continuous welded rail. acceleration or braking force, temperature change and shrinkage. Proper level of the longitudinal prestress of the tendons that can ensure integrity of the transverse joints in the deck system is of a primary importance. To this aim, the longitudinal tensile stresses induced by the design loads are derived using three-dimensional finite element analyses, design codes and theoretical equations for the frequently adopted PSC composite girder railway bridge. The estimated proper prestress level to counteract those tensile stresses is over 2.4 MPa, which is similar to the case of the highway bridges.