Hydration Heat Stress Change Rule in the Construction of Segment No. 0 of PC Box Girder Bridge

In the construction process of segment No. 0 of large PC box girder bridge, the time difference of hydration beginning time, exothermic speed and temperature peak beginning time between the lower first casting and upper later casting concrete, so as to result in the obvious temperature gradient with time changes in the internal structure. The lower concrete would be constrained by the upper concrete and produce constraint internal force, which results in the temperature crack. Combined with engineering examples and comprehensively considering the climate characteristics and the temperature change rule in Changchun, the hydration heat analysis model is established in this paper. By defining the construction phase and stimulating the casting time difference of each layer in the casting process of segment No. 0, the distributions of temperature field and stress field in all critical periods can be obtained. By comparison with measured data, it can be concluded that the identified analysis parameters, such as heat conduction coefficient, heat transfer coefficient, and convection coefficient, all adapt to the climate characteristics in Changchun. Besides, temperature analysis model of hydration heat is accurate and user friendly. What's more, the method of defining construction phase can effectively stimulate the on-site casting process of concrete box girder. Therefore, the outcome has a certain reference value for engineering practice, especially for the construction of segment No.0, where the climate characteristics are similar to Changchun.