Experimental behaviour of concrete-filled double-skin corrugated steel tubes under eccentric compression

Abstract

Concrete-filled double-skin corrugated steel tube (CFDCST) is a novel type of hollow section steel-concrete composite member comprising inner and outer layers of galvanized corrugated steel tubes (CSTs) with an interlayer of hollow reinforced concrete (HRC). Previous studies have clarified its behaviour under axial compression. This study further conducted an experimental investigation on 14 large-scale short specimens subjected to eccentric compression, including 11 CFDCST and 3 HRC specimens. The experimental variables are eccentricity ratios, hollow ratios, outer CST thicknesses, and longitudinal reinforcement ratios. The failure modes, load–lateral displacement curves, key mechanical indicators, and strain/stress distributions were analyzed, with the working mechanisms addressed. The experimental results indicate that the CFDCST specimens exhibited desirable mechanical performance and high structural efficiency. The failure modes and mechanical performances showed effective improvement compared to the HRC specimens with the same reinforcement configuration. Specifically, the compressive bearing capacity improved by 32.2–34.9 %, while the ductility index increased by 68.5–115.2 %. The outer thin-walled CSTs provided high-level confinement while the inner thin-walled CSTs effectively maintained the cross-section integrity to prevent performance deterioration. Ultimately, the bearing capacity prediction methods for CFDCST members under eccentric compression are discussed, with design suggestions proposed.