"Inelastic Behaviour Of Thin-Walled Circular Steel Tubular Columns Unde" by Njiru J. Mwaura

Date of Award

January 2022

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

First Advisor

IRAJ D. MAMAGHANI

Abstract

Thin-walled circular steel tubular columns have been used as bridge piers widely around the globe because of their excellent seismic performance: ductility, strength, and energy dissipation capacity. This thesis investigates the inelastic behavior of thin-walled circular steel tubular columns with a uniform section and thin-walled circular steel columns with diaphragms. The loading protocol considered for this study is either pushover or cyclic lateral loading in the presence of a constant axial load. The effects of a pushover and cyclic lateral loading on the behavior of the thin-walled circular steel tubular bridge piers have been evaluated through analysis of failure mode, hysteresis curve, envelope curve, stiffness and strength degradation characteristic, and energy-dissipating capacity, including interaction effects of local buckling and flexural buckling, and post-buckling regimes. The analysis applies the finite element model (FEM) that considers the effect of both material and geometric nonlinearities. Also, in this research a comprehensive parametric study was carried out to investigate the effects of the key design parameters and namely are: the radius to thickness parameter (Rt), the column slenderness ratio parameter (λ), and the magnitude of axial load (P/Py). Finally, a series of proposed formulae for strength and ductility evaluation for thin-walled circular steel tubular columns are given.

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