Abstract
To investigate the distribution characteristics and development patterns of the hydration heat temperature field in large-tonnage PC box girders during whole-span prefabrication, field monitoring and analysis of the hydration heat temperature field were conducted during the casting process of a 50 m PC box girder. The research results indicate that: during the whole-span prefabrication process, the hydration heat temperature in the box girder exhibits a development process of "rapid heating—high temperature maintenance—slow cooling"; the temperature distribution at each cross-section is left-right symmetrical, with the maximum temperature occurring at the core of the web mid-section of Section S1, reaching 74°C; the maximum temperatures at Sections S1 and S2 both exceed 70°C, and the high temperature duration is relatively long; the temperature difference at each cross-section shows a development process of "rapid increase—slow decrease", with the maximum temperature difference occurring between the web—top slab junction and the top slab surface, and the temperature difference distribution is essentially consistent on both left and right sides; the maximum temperature differences at Sections S1 and S2 both exceed 25°C, which can easily cause concrete cracking, and corresponding temperature control measures should be adopted during the box girder construction process. The research findings can provide a reference for the whole-span prefabrication of large-tonnage PC box girders.
Full Text
Experimental Study on Hydration Heat Temperature Field of PC Box Girders
Wang Xiaofei
China Railway 16th Bureau Group Third Engineering Co., Ltd., Huzhou 313000
Abstract
To investigate the distribution characteristics and development patterns of the hydration heat temperature field in large-tonnage PC box girders during full-span prefabrication, field monitoring and analysis were conducted during the casting of a 50 m PC box girder. The results demonstrate that the hydration heat temperature follows a distinct three-stage development pattern: rapid heating, sustained high temperature, and slow cooling. Temperature distribution is symmetric across each cross-section, with the peak temperature of 74°C occurring at the core of the web mid-section of cross-section S1. Both S1 and S2 cross-sections experienced peak temperatures exceeding 70°C for extended durations.
The temperature differences across cross-sections exhibit a pattern of rapid increase followed by gradual decrease. Maximum temperature differences occur between the web-deck junction and the deck surface, with essentially identical distribution on both sides. Both S1 and S2 cross-sections exhibited maximum temperature differences exceeding 25°C, creating significant cracking risk. Corresponding temperature control measures should therefore be implemented during construction. These findings provide valuable reference for the full-span prefabrication of large-tonnage PC box girders.
Keywords: bridge engineering; concrete box girder; hydration heat; temperature field; field monitoring