Journal:Structures

Abstract:This study investigates the compressive behavior and constitutive relationship of concrete confined by steel tubes with delayed confinement, a condition arising from interfacial void defects between the steel tube and concrete infill in concrete-filled steel tubes (CFSTs). Axial compression tests were conducted on 24 delayed confined CFST (DC-CFST) specimens, considering key parameters including the magnitude of gap between steel tube and concrete core and the diameter of high-strength bolts connecting the steel tube components. The failure modes, load-displacement, and load-strain responses were systematically analyzed. The results demonstrate that the DC-CFST specimens failed by concrete crushing coupled with tensile fracture of the high-strength bolts. Notably, the load-displacement curves of specimens with void defects exhibited a distinct bilinear response, characterized by a sharp post-peak strength degradation followed by a secondary ascending branch, which significantly differed from the responses of fully bonded specimens. The extent of the strength decay intensified with an increasing void gap, while the slope of the secondary branch gradually decreased. Based on the experimental data and theoretical analysis, a stress-strain model was developed for axially compressed DC-CFST. The proposed model shows good agreement with the test results, effectively capturing the unique mechanical behavior of DC-CFST. Furthermore, finite element analysis models established in ABAQUS validated the experimental findings and provided additional insights into the mechanical performance.

Indexed by:Journal paper

Page Number:2026,89:112000

Translation or Not:no

Included Journals:SCI

First Author:柴振岭

Co-author:董思涵,林志颖,姜航

Correspondence Author:叶勇