Ancient wooden covered bridge in Taoyuan, China – A mechanical analysis

Wooden covered bridges attract attention due to their architectural appearance and manufacturing technique. In this study, an ancient wooden covered bridge in Taoyuan, China, has been investigated, mainly with respect to its construction form and mechanical behavior. First, the same type of raw material used for the bridge, namely, beech, was tested to obtain its mechanical properties. Then, the material experimental values were used in a finite element model to study the mechanical behavior of the bridge, and the stress state and internal forces of the bridge were obtained. The numerical results indicate that the maximum deflection of the bridge of 10.73 mm under gravity load meets the requirements of not exceeding L/600 in the specification while it reaches 15.62 mm under both the gravity load and crowd load, exceeding the limit by 1.3%. The maximum and minimum normal stress of 1.13 MPa and -2.03 are much less than the ultimate tensile and compression strength of the wood, respectively. This means that the structural safety performance of the ancient wooden covered bridge is acceptable if the pedestrian number be controlled effectively. Finally, some tiny damage of the bridge was apparent. Some suggestions were provided according to the numerical results and the complex actions of long-term loads and a severe environment on the bridge to preserve this old historical bridge.