Effects of temperature on the deflection of cable-stayed bridges during cantilever erection

To investigate the effects of temperature on the deflections of cable-stayed bridges under cantilever construction, the girder and tower of bridges are considered cantilever beams with continuous elastical supports, whose supported stiffness depends on the tensile stiffness of the cables. Then, a finite element model of the beams is built to formulate an approach for calculating the temperature-induced deflections. In this approach, the temperature actions are considered equivalent loads acting on the beam, and the responses of the bridges are analysed under several types of actions. The effectiveness of the approach was validated using temperature and deflection measurements from the Zengjiang Bridge. The results show that a combination of the daytime temperature actions produced downward deflections of the girder, which reached their maximum at approximately 15:00 during a day period, and the deflections are greatly affected by the vertical-temperature gradient along the girder section, as well as cable-temperature variation. With an increase in the cantilever length, the effect of the latter increases, but the effect of the former decreases. These temperature-induced deflections are restricted by the installation of new cables, and some of them may be unrecovered, which affects the alignment of the girder in the completion state.