Effect of Circumferential Gap on Dynamic Performance of CFST Arch Bridges

Abstract Until recently, ordinary concrete has been used to construct concrete-filled steel tube (CFST) arch bridges in China, which has resulted in the formation of circumferential gaps around steel–concrete interfaces. Furthermore, it has been found that harsh environments enlarge gaps, resulting in serious defects that decrease arch rib stiffness and even affect the dynamic features of the whole bridge. Hence, a finite element analysis and a reduced-scale model experiment were performed on a serviced CFST arch bridge rib member containing circumferential gaps to determine member tangent stiffness affected by the gap depth parameters under a small eccentric axial compression test. Next, tangent stiffness was applied to analyze the natural frequencies and modal vibrations of the whole bridge to study the influence of defects on bridge dynamic performance. A determination system was proposed for the effect of interface circumferential gaps on rib member stiffness and the dynamic features of the whole bridge. Therefore, this research provides a theoretical analysis method for CFST arch bridge maintenance and rehabilitation strategy.