NONLINEAR ANALYSIS OF (UN)BRACED STEEL FRAMES SUBJECTED TO HORIZONTAL LOAD

Abstract

<p>This paper presents a 2D nonlinear analysis of the load-carrying capacity of unbraced and concentrically braced steel frames subjected to lateral loading. The study was conducted using the incremental ("step-by-step") analytical method and finite element analysis. The effects of material and geometric nonlinearities, axial force, and brace cross-sectional area on the structural response were investigated. Axial force had no significant influence on the formation of plastic hinges in the analyzed systems. The results show that including geometric nonlinearity and a strain-hardening material model does not significantly affect the overall structural response. The numerical models were validated against analytical solutions, with differences below 5%. Increasing the brace cross-sectional area improves both the load-carrying capacity and stiffness, without affecting the location or sequence of plastic hinge formation.</p>