Improving the Compression Behaviors of Perforated Plates with Slotted Holes Using Strengthening Stiffeners

Abstract

This research focuses on the strengthening methods used for improving the compression behaviors of plates perforated by slotted holes, as provided in steel bridge pylons for the purposes of access and service. The rectangular plates that were investigated each have a centric slotted hole and are simply supported on four edges in the out-of-plane direction. Three types of strengthening stiffeners, ringed stiffener (RS), flat stiffener (FS), and longitudinal stiffener (LS), are considered. Uniaxial compression tests are first conducted for 41 specimens, of which seven are unstrengthened plates and 34 are strengthened plates. Stress concentrations, failure patterns, and elasto-plastic ultimate strengths are experimentally investigated. Finite element models are further developed to predict the ultimate strengths of plates with various dimensions. The FE results are validated by the test data. The influences of nondimensional parameters including plate aspect ratio, stiffener slenderness ratio, and stiffener thickness on ultimate strengths are revealed on the basis of numerous parametric studies. Comparisons in strengthening efficiencies of stiffeners are also made by considering stiffener weight. The simplified formulations used for predicting the compression strengths of strengthened plates are proposed. The net cross-sectional area–based strength, including stiffeners, is also recommended for the strength approximation in engineering applications.