Tests on CFS Laced Columns Composed of Plain Channels: Behavior and Design

Abstract

A test program on cold-formed steel (CFS) laced columns fabricated using plain channels has been presented in this study. Twelve specimens with single and N-type lacing configurations were fabricated. The lacing plates and the end-plates were connected to the chords by using self-drilling screws. The effect of critical parameters, like lacing slenderness and transverse chord spacing, on the performance of laced columns under concentric axial loading was investigated. The aspect ratio of the built-up section of the specimens varied from 0.75 to 1.25. The relative slenderness of the unsupported chord (with respect to the global slenderness of the column) ranged from 0.31 to 0.87 in single-laced columns and 0.15–0.44 in N-type laced columns. The performance of the specimens was assessed in terms of their failure modes, peak strengths, and load-displacement trends. Lastly, the strength estimations from both the current American (AISI S100-16) and European (EN1993-1-3) standards were evaluated by comparison against the test strengths. It was noted that both these codes overpredicted the strength of the laced column specimens by up to about 25%. The modified design rules catering to both American (AISI S100-16) and European (EN1993-1-3) standards, previously proposed by the authors for CFS battened columns, were assessed, and their strength predictions were found satisfactory for both types of lacing configurations. The reliability index determined using the modified design rules was approximately equal to three, indicating high reliability.