Flexural performance of circular concrete‐filled double steel tubular members: Testing, modeling, and strength predictions

Abstract

This paper presents experimental and numerical investigations on circular concrete‐filled double steel tubular (CFDST) members under flexural load. Seven specimens including five CFDST specimens were tested and the test parameters included the effects of concrete compressive strength, the thickness of the steel tubes, and the diameter ratio on their flexural performance. The final failure modes, moment (M)‐curvature (ϕ) curves, deflection curves of specimens, and distributions of section longitudinal strains were analyzed and reported in this study. A nonlinear finite element model (FEM) was then developed for the CFDST members. After successful validation in ultimate strengths and failure modes, parametric studies were performed by using the verified FEM. A simple formula for calculating the flexural capacity of CFDST members was proposed and compared against several design codes to investigate the design accuracy. Based on this study, it was found that the CFDST members exhibit ductile behavior under flexural load. Increasing the steel area, particularly for the outer tube improved the flexural capacities of the members. Furthermore, the existing design codes were found to be remarkably underestimating the moment capacities of CFDST members whereas the design formula proposed can predict the ultimate flexural capacity with reasonable accuracy.

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

“…into CFSTs, thus the steel-reinforced concrete-filled steel tubes (SRCFSTs) are formed. [5][6][7][8][9][10][11][12][13] Existing research results have confirmed that some types of steel reinforcing elements (such as reinforcement cages, latticed steel angles, steel tubes, etc.) can provide an additional confining effect on the enclosed concrete, 5,6,12,13 hence the bearing capacity and ductility of SRCFSTs can be improved.…”

“…In recent years, to improve the compression and shear properties of the core concrete in CFSTs, some scholars have added different types of steel reinforcing elements (such as the reinforcement cages, profiled steels, steel tubes and lattice steel angles, etc.) into CFSTs, thus the steel‐reinforced concrete‐filled steel tubes (SRCFSTs) are formed 5–13 . Existing research results have confirmed that some types of steel reinforcing elements (such as reinforcement cages, latticed steel angles, steel tubes, etc.)…”

Seismic Behavior Investigations of the Haunched Joint with Ribbed Anchor Webs in CFDST Structures

“…The concrete-filled double steel tubular (CFDST) column, composed of the circular section, offers improved axial strength, ductility, and energy absorptions compared to its CFST counterparts and, therefore, has significant potential to be widely applied in future constructions, especially in highintensity earthquake areas [1][2][3][4]. Besides, CFDST column facilitates the selection of eco-friendly and green concrete, reducing the adverse impact of concrete on the environment [5].…”