It was very important that during cast in place cantilever segment construction of a concrete girder bridge the elevation of the traveling form had to be adjusted considering the deflection changes induced by solar temperature effects. In this paper, a practical computation method is presented to simulate instantaneous temperature effects of box girder bridges. Formula of instantaneous temperature and instantaneous relative humidity were proposed according to the observation results of Guanyinsha Bridge and the information of local weather condition. The instantaneous maximum temperature of the deck surface at daytime was determined using boundary conditions of heat flow equations. According to the observation, temperature of the deck surface varies along transverse direction with parabolic distribution, and vertical temperature gradients for the left web region and right web region were different. Therefore, for analysis of thermal stresses using the space beam model, the nodal forces were described separately by a double moment. The errors of deflection were about 6% using this method indicating that it may be applied to predict solar temperature effects of concrete bridges during construction.
