A new study published in Engineering presents an innovative cyclic construction method for steel–ultra-high-performance concrete (UHPC) composite truss (SUCT) arch bridges, addressing key challenges in the construction of long-span arch bridges and offering significant cost and load-bearing advantages.

The research, conducted by a team from Hunan University, China, introduces a cyclic construction method that involves multiple closures of the arch ring from inside to outside, using an automated sliding connector to mitigate stress superposition and reduce construction costs. The proposed method aims to extend the span of arch bridges to 600–1000 m, overcoming limitations posed by the substantial self-weight, high construction expenses, and complex erection processes of conventional arch bridges.

According to the paper, the cyclic construction method divides the process into six stages, starting with the prefabrication and cantilever assembly of the inner arch using temporary cables. Once the inner arch is closed and can bear loads independently, the cables are removed and reused for the outer arch. The sliding connectors, which link different arches, are designed to release vertical shear forces and transfer bending moments to the inner arch, ensuring minimal stress superposition.

Experimental analysis revealed that when the sliding connectors are in the slidable state, approximately 10% of the load is transferred to the inner arch, representing about 20% of the load in the locked state. However, during spring conditions, about 25.5% of the negative bending moments are transferred to the inner arch. The study also found that optimizing the sliding surface to a vertical orientation (0°) and lubricating the sliding plate and chute effectively isolate negative bending moments and vertical loads from the inner arch, significantly enhancing crack resistance and load-bearing capacity.

The optimized design reduces the load borne by the innermost arch to 48% compared to the non-sliding connector scheme and 85% compared to the original design. Moreover, the load distribution across all truss arch rows becomes more uniform, advancing both the theoretical understanding and practical implementation of innovative arch bridge construction.

The findings suggest that the cyclic construction method offers distinct advantages over traditional techniques, ensuring the construction feasibility of SUCT arch bridges. The study concludes that the proposed method and optimized sliding connectors can significantly reduce construction costs and improve the structural performance of long-span arch bridges, offering valuable insights for the infrastructure sector.

Future research will focus on further examining the working mechanism of the sliding connectors through numerical analysis and parameter studies, as well as investigating the mechanical performance of the arch ring after completing cyclic construction. This continuous improvement aims to lay a foundation for promoting the construction of SUCT arch bridges and enhancing their applicability in practical engineering projects.

The paper “Cyclic Construction and Load Redistribution in Steel–Ultra-High-Performance Concrete Composite Arch Using Optimized Sliding Connectors,” is authored by Guang He, Xudong Shao, Suiwen Wu, Junhui Cao, Xudong Zhao, and Wenyong Cai. Full text of the open access paper: https://doi.org/10.1016/j.eng.2025.05.014. For more information about Engineering, visit the website at https://www.sciencedirect.com/journal/engineering.