Pattern and extreme value for insolation temperature gradient of concrete solid slab girder bridges

ObjectiveThis study investigates to clarify the temperature gradient patterns for concrete solid slab bridge, and to accurately evaluate the temperature effects in insolation conditions.MethodFirst, the finite element analysis with ABAQUS was conducted on the temperature field of concrete slab bridge. The simplified temperature distribution characteristics yielded the vertical temperature gradient patterns. Second, the long-term simulations of concrete slab temperatures were conducted by using observational data for a decade from a meteorological station at the bridge site. A super-threshold extreme value model based on GP distribution yielded representative temperature difference values for a 100-year-return period event. Finally, the proposed temperature gradient pattern was compared with existing specifications. The influence of different asphalt pavement thicknesses on temperature distribution was investigated.ResultThe outer surface of slab beam rapidly heated up under insolation and ambient temperature effects, while the core concrete exhibited slow heat transfer and gradual warming. The cross-section displayed the gradient pattern characterized by high temperatures at the top and bottom surfaces, and low temperatures internally. The nonlinear temperature distribution along the height of concrete slab beam could be described using two exponential curves, i.e., one for the top surface heating segment due to direct radiation, and the other for the bottom surface heating segment due to reflected radiation. The asphalt pavement significantly influenced the top temperature difference in vertical thermal gradient of concrete slab bridges. As the pavement thickness increased from 0 to 150 mm, the top temperature difference decreased from 21.59 ℃ to 10.86 ℃, exhibiting a clear linear relation with the R2 of 0.989 5. This excellent fit provided a reference for accurately determining temperature gradient of concrete slab bridges with different pavement thicknesses.ConclusionThe proposed vertical temperature gradient pattern for concrete slab bridges eliminates the isothermal segments found in China's specifications and European specifications, achieving better temperature continuity. The derived temperature difference values align more closely with the requirements of the limit state design method.