Experimental Study of CFST Interface Bonding Damage under Sustained Loading
长期荷载作用下CFST界面粘结损伤试验研究

In order to investigate the relation between interface bonding property and loading time of in-service concrete-filled steel tube (CFST), push-out test of 7 round CFST specimens was carried out by taking time period as basic parameters. Experimental results indicate that the interface cohesive force of concrete-filled steel tube declines with the extension of loading time. Then, load-slip curves for each specimen were obtained, based on experimental results. According to ANSI/ACI 308-1992 concrete curing procedure, concrete creep strain produced by sustained loading for each tested specimen was obtained. Based on damage mechanics, the interface damage variable was defined, and the relation between the concrete creep strain and the damage was derived. Finally, the interface bond-slip constitutive relation including interface damage variable was obtained by regression.