Innovative key-segment closing method using thermal prestressing technique for partially earth-anchored cable-stayed bridges

This paper proposes an innovative key-segment closing method for partially earth-anchored cable-stayed bridges erected using free cantilever construction method, and examines its feasibility by performing a construction sequence analysis. The proposed method is based on the thermal prestressing technique, which gives an artificial heat to the girder in a cantilever state, in order to introduce the closing force required for connecting the key-segment to the adjacent segment by means of thermal expansion. The new method not only provides a feasible closing method for partially earth-anchored cable-stayed bridges, but also has a significant effect in reducing the axial force in the girders. A construction sequence analysis of an example bridge shows that the axial forces in the girders and the uplift forces at the bearings are reduced by a considerable amount due to application of the thermal prestressing method, whereas the member forces of cables and pylons are slightly changed. Therefore, it is verified from this study that the structural capacities of the girders and the bearings of the partially earth-anchored cable-stayed bridges can be effectively enhanced by application of the proposed method.