A theoretical model for estimating the flexural stiffness of CHC joints

The CHC joint is a steel–concrete composite insert-type joint, which has been successfully implemented at Shenzhen Pingxi station in China, and has advantages in terms of construction efficiency and environmental sustainability. However, the design methodology for CHC joints remains unreported. This study began by clarifying the moment–rotation relationship of CHC joints through experimental methods. Subsequently, a novel a dual-spring–rigid arm (DSRA) theoretical model to estimate the joint's bending stiffness was developed. The parameters for the DSRA were derived from a series of rigorous mechanical theoretical derivations, resulting in a concise explicit expression for the bending stiffness. It was found that the theoretical DSRA model was able to accurately estimate the bending stiffness of CHC joints during service, with an average error in the calculated results of just 2.1%. This innovative approach holds promise for broader application in joint design and analysis, offering valuable insights for future research and practical implementation.