Numerical Simulation on Thermomechanical Coupling Behavior of Early-Age Concrete in the Large-Scale Steel-Concrete Connecting Segment of a Hybrid-Girder Cable-Stayed Bridge

摘要

Large-scale connecting segments can provide reasonable load transition in hybrid girders, and have been broadly used in long-span cable-stayed bridges. However, the large volume of concrete in connecting segments bears a high cracking risk at an early age in the life of the concrete. In this study, field measurement and numerical simulation were performed on a large-scale connecting segment with early-age concrete to investigate its thermomechanical coupling behavior. Based on the thermal behavior modeling, mechanical behavior modeling was subsequently carried out by considering the comprehensive effects of temperature history and actual age on the development of the hardening concrete's mechanical properties. Both measurement and simulation show that the peak temperature can reach about 90 degrees C, which is far beyond expectation, and high cracking risks exist in the external surfaces of concrete in the monitored connecting segment. To reduce the cracking risk, methods of multilayer pouring and cooling pipes were then adopted to quantitatively evaluate the anti-cracking effects. Results show that embedding cooling pipes in the thick concrete slabs can significantly lower the peak temperature, further reducing the cracking risk of the concrete. (C) 2020 American Society of Civil Engineers.