Effective slab width for beam-end flexural strength of composite frames with circular-section columns

Abstract

The calculation of the ultimate loading capacity of composite frame beams is an important step in the design of composite frame structural systems. This paper puts forward the Compression-on-Column-Face, Compression-on-Transverse-Beam and Tension-on-Transverse-Beam mechanisms to explain the mechanism of the circular-section column frame in the ultimate loading state, and an extensive parametric analysis is conducted on a series of typical composite beam–column joint subassemblies using the nonlinear finite-element simulation method. First, an elasto-plastic elaborate finite element model is established to conduct the parametric analysis of the exterior joint of the circular-section column frame under negative and positive moment. Furthermore, based on the parametric analysis, the simplified design formulae of the slab effective width are derived. The proposed formulae and numerical results are compared for the effective slab width for composite frames with circular-section columns, and the relative errors are little. In addition, the applicability of the formulae to calculate the effective slab width at the interior joints in the circular-section column frame is verified. Finally, this paper compares the proposed formulae with formulae in the current design codes, and the proposed formulae provide the most accurate results to predict the effective slab width and ultimate loading capacity.