Century-old Covered Bridge with Cantilever Beams in China

Abstract

Covered bridges are well-known ancient structures in China due to their unique construction and appearance. Among the remaining covered bridges, cantilever covered bridges have been best preserved, as they are mostly distributed in remote and isolated mountain areas and are thus free from the destruction caused by modern civilization. Changfeng covered bridge, located in a mountain area in Xinhua County, Hunan, China, is a well-preserved cantilever timber bridge with more than 150 years of history and is still in service today. This paper describes the structures and component materials of this particular bridge in detail. The novel construction idea and its functional flexibility are also discussed. The structural system efficiently reduces the deflections and bending moments of the wooden beams, thus extending the spans. The stress state and mechanical behaviour of the bridge were also analyzed using the finite element method. According to the results, the bridge transfers the loads downward layer-by-layer through its cantilevers. The various cantilever beams tend to even the forces and provides a better structural integrity and safety. This ancient wooden covered bridge should be well protected for its special features of light weight, large carrying capacity and environmental friendliness. This type of bridge can also be constructed as a scenic pedestrian bridge of small-medium span.