Eccentric loading behavior of steel tube columns filled with steel‐fiber‐reinforced recycled concrete

Abstract

A comprehensive study focuses on the eccentric compressive behavior of steel‐fiber‐reinforced recycled concrete filled steel tube (SRCFST) columns. A total 39 stub columns are tested, and the variables include eccentricity ratio (e/r), steel fiber volume, quality replacement rate of recycled aggregate, concrete strength grade, and diameter–thickness ratio of steel tube. Failure mode, the load–lateral deflection behavior and the moment–curvature response are analyzed. The load–moment interaction relationships, the load–strain responds and the neutral axis position are researched. The results show that the use of recycled aggregate causes the little‐to‐no influence on the eccentric loaded performance of SRCFST columns with a relative smaller e/r. However, the ultimate load and deformability of the columns with higher e/r both decreases rapidly. Adding steel fibers can offset this adverse effect. The addition of steel fibers sustains a higher relative compression region height in the cross section. The ultimate load descent of SRCFST columns due to the increase of e/r is slower than ordinary concrete filled steel tube and recycled aggregate concrete filled steel tube columns. Moreover, on the basis of the unified theory, a calculation model is proposed to predict the ultimate capacity of SRCFST columns under combined loadings. The model captures well the compressive response of SRCFST columns.

Eccentric compression behavior of circular concrete‐filled steel tubes reinforced with internal latticed steel angles

“…It should be noted that the simulated bending strength of the counterpart specimens which were used for plotting the interaction curves was acquired from the previous study, 16 the bending moment caused by eccentric compression was equal to the product of the compression load and the sum of eccentric distance and lateral deflection. 29 As can be seen from Figure 12, the structural steel index ρ has an obvious influence on the interaction curves, for specimens with higher value of ρ, the "Balance point" 2 moved inwardly. The result showed that the horizontal coordinate of the "Balance point" was relatively smaller for specimens with higher structural steel index ρ.…”

“…Figures 12 and 13 depicted the influence of the structural steel index ρ , confining factor ξ and slenderness ratio λ on the N / N u ‐ M / M u curves of the CFSTs reinforced with latticed steel angles. It should be noted that the simulated bending strength of the counterpart specimens which were used for plotting the interaction curves was acquired from the previous study, 16 the bending moment caused by eccentric compression was equal to the product of the compression load and the sum of eccentric distance and lateral deflection 29 …”