Failure mechanism and load carrying capacity of an arched partially CFST bridge tower considering different concrete filling lengths

The Partially Concrete Filled Steel Tube (PCFST) structure has gradually been applied to bridges as the main load carrying components in recent years, owing to the advantages of light weight and high stability. The failure mechanism and load carrying capacity of PCFST structure highly depends on the concrete filling ratio. For this purpose, the failure mechanism and parametric analysis of a single arched PCFST cable stayed bridge tower are investigated by using both refined solid element simulation and quasi-static experiment. The results shows that the PCFST arched tower experiences asymmetrical instability failure subjected to quarter span symmetrical loading, and the plastic hinges appears firstly at the tower arch closely above the tower columns, and then the bottom of the tower columns, forming a rotating mechanism leading to the instability failure. Filling concrete or not will result in two opposite deforming propagations of the plastic hinges, and when the concrete filling length exceeds the length of plastic hinge, the initial rigidity and ultimate load carrying capacity of the PCFST structure will sharply increase. Finally, according to the results of the extended parametric analysis based on the real size simulation, an improved initial stress reduction coefficient of PCFST structure is then suggested.