Effects of Cap Gap and Spiral-Welded Seam Composite Defects on Concrete-Filled Steel Tubes

Abstract

Many old concrete-filled steel tube (CFST) arch bridges use consisted of ordinary concrete and spiral-welded steel tubes. However, low strength of spiral-welded seams (SWS) and cap gaps of concrete due to fluidity composed composite defects in CFST arch bridges. In the current work, a finite element analysis has been performed using ultrasonic scanning field tests on the bearing capacity of a serviced CFST arch bridge rib with a cap gap and reduced SWS strength exposed to a weak eccentric axial compression. The nonlinear behaviors of different components and composite defect influence on CFST performance were also studied. Composite defect influences on the bearing capacity of CFSTs were also experimentally studied. This research proposed a theoretical analysis method for the maintenance and restoration strategy of CFST arch bridges.