Practical Advanced Analysis for Braced Steel Frame Design

Abstract

This paper presents three practical advanced analysis procedures for a two-dimensional braced steel frame design. These procedures can be used to assess realistically both strength and behavior of a structural system and its individual members in a direct manner. As a result, the procedures can be used for design without tedious separate member capacity checks, including the calculations of K -factor. Herein, key factors influencing steel frame behavior are described (including gradual yielding associated with flexure; residual stresses; second-order effects; and geometric imperfections) and simple procedures to enable designers to assess this behavior are provided. The procedures incorporate the refined plastic-hinge concept for spread of plasticity together with practical modelings for geometric imperfections. The strengths predicted by the proposed procedures are then compared with those predicted by the exact plastic-zone analysis as well as by the conventional LRFD procedure. A case study is also given for a braced frame. It is concluded that the proposed procedures are suitable for adoption in practice.