Overall stability design of L-shaped batten-connected multi-cell concrete-filled steel tube columns under axial compression

Abstract

This paper proposes the L-shaped batten-connected multi-cell concrete-filled steel tube columns (L-BCMC-CFSTCs) and presents its overall stability design method under axial compression. First, the test study is conducted to investigate the failure mechanism and load-carrying capacity of L-BCMC-CFSTCs under axial compression, and the comparison between the test result and the simulation by finite element method (FEM) in Abaqus software is carried out. Then the buckling behaviors and stability load-carrying capacity of the pin-ended L-BCMC-CFSTCs under axial compression is studied theoretically and numerically. The eigenvalue buckling analysis is conducted to investigate numerically into the buckling modes of L-BCMC-CFSTCs, indicating that slender L-BCMC-CFSTCs could mostly buckle in global flexural buckling, while short L-BCMC-CFSTCs could mostly buckle in independent chord buckling. Based on the simplified theoretical formula of the buckling loads corresponding to each buckling mode, the results obtained from FEM are used to establish the modified coefficients for the design formula of each buckling load. On the other hand, the inelastic analysis is carried out to investigate the failure mechanism and overall stability capacity of L-BCMC-CFSTCs under axial compression, which are used to develop the φ-λn curve accordingly. In addition, to attain an economical design, it is recommended that the batten-to-column height ratio should be taken as 30%–50 %, and for slender L-BCMC-CFSTCs, increasing the length of batten in the design could be more efficient than increasing the length of flange column.