Study on In-Plane and Out-of-Plane Stiffness of Cold-Formed Steel Composite Floor with Opening

Abstract

In this study, experimental investigations were conducted to study the hysteresis and flexural performances of cold-formed steel (CFS) composite floors. The failure modes of the hysteresis specimens were damage of the screws connecting the composite slab and end joists, as well as bond-slip failure between the slab material and CFS form-deck. The failure modes of the flexural specimens involved shear deformation and buckling of the joists, as well as bond-slip failure between the slab material and CFS form-deck. Second, finite-element (FE) models were constructed and validated against the test data. Subsequently, numerical analysis models for floors with openings were developed. Also, parametric studies were performed by considering the influences of opening size, strengthening, and eccentricity on stiffness for floors with openings. The results revealed that actions to enhance stiffness for floors with openings involve minimizing the opening size, setting the opening strengthening, and keeping the opening centered. Finally, theoretical methods to determine the in-plane and out-of-plane stiffness for the floors with openings were proposed, and the calculations matched well with the numerical results.