Thin-Walled Steel Tubular Circular Columns with Uniform and Graded Thickness under Bidirectional Cyclic Loading

Abstract

Abstract Thin-walled steel tubular circular columns are becoming an increasingly attractive choice as cantilever bridge piers due to their architectural, structural and constructional advantages. This paper aims to evaluate the strength and ductility of thin-walled steel tubular circular columns with uniform thickness (BC) and graded thickness (BGC) under bidirectional cyclic lateral loading in the presence of constant axial force. The analysis is carried out using a finite-element model (FEM) which is substantiated based on the experimental results in the literature. Then, the proposed BGC column with size and volume of material equivalent to the BC column is investigated. As a part of this research, a comprehensive parametric study is carried out to investigate the effects of main design parameters including: radius-to-thickness ratio parameter (Rt), column slenderness ratio parameter (λ), magnitude of axial load (P/Py), and number of loading cycles (N) on the strength and ductility of both BC and BGC columns under bidirectional cyclic lateral loading. Finally, design formulae of ultimate strength and ductility of BC and BGC columns are derived.