Structural Performance of Concrete-Filled Rectangular Steel Tubular Joints with Perfobond Rib in Bridges using Damage Model

A composite tubular truss bridge has been widely used in highway projects because of its short construction period and excellent mechanics characteristics. The joints' configuration and deformation of the composite truss bridge are of vital importance. Concrete filled tubular joint (CFTJ) has been approved as an effective way to enhance the loading capacity. Although the bonding force between concrete and rectangular tube is not distributed uniformly, this will cause the bond-slip behavior in the tube. To improve the interface bonding strength, perfobond rib is installed inside tube on the joint. This paper represents the damage mechanism of both CFTJ and CFTJ with perfobond rib through experiment calibration and numerical methods. The author proposes a new method to evaluate the steel joints' damage and fracture based on the stress-modified fracture strain model. The damage model, which considers both critical fracture strain and stress triaxiality, is calibrated by experiment to validate its accuracy. The user subroutine tool provided by commercial software ABAQUS was implemented to establish the damage model. Through analysis of CFTJ and CFTJ with perfobond rib, CFTJ with perfobond rib was found to have considerably much high constraint capability to concrete than CFTJ. The damage mechanism difference of the two types of joints is compared in the paper.