Analysis of the Stress-Strain State of Steel Solid-Web and Perforated I-Beams Used in Pitched Roof Structures

Abstract

The paper presents a numerical investigation of the stress-strain state of steel solid-web and perforated I- beams in pitched roof systems using the finite element method (FEM) implemented in the ANSYS software environment. Single-pitch and double-pitch beams configurations were analysed under different boundary conditions (hinged and fixed supports at both ends) and roof inclinations varying from 0° to 45°, typical for industrial buildings. The principal parameters of the stress-strain state were analysed, namely deflections and equivalent (von Mises) stresses along the beam flanges, as well as equivalent stresses around the web openings. The results show that the largest deflections occur in hinged beams, while fixed significantly reduces them. For most configurations, maximum deflections are located at mid-span; however, in rigidly fixed double-pitched beams, they shift toward the quarter span. Perforated beams exhibit higher stiffness compared to solid counterparts. The distribution of equivalent stresses in perforated beams is non- uniform due to the presence of openings and local stress concentrations, which necessitated evaluation based on averaged values. Fixed beams, particularly double-pitched ones, demonstrate substantially lower average stress levels in flanges than hinged systems. Maximum stresses in perforated beams occur around end openings and generally decrease with increasing slope, with the most pronounced reduction observed in rigidly fixed double-pitched beams.