Fatigue Analysis of Unconfined Concrete Columns

Abstract

Using an energy based methdology, this report explores the various possible failure modes in non-seismically designed concrete structures including: unconfined concrete fatigue; bond failure in anchorages and lap splices; compression buckling of the longitudinal reinforcement; fracture and fatigue of the longitudinal reinforcement; and shear failure of the columns. Theoretical models capable of predicting strength degradation over the cycles of loading that lead to failure are developed and verified by comparing with experimental results. Numerical examples are presented at the end of each section to explain the working procedure of the proposed evaluation methodology. The individual fatigue theories are generalized so that mixed failure modes in reinforced concrete pier bents can be tracked during cyclic loading. Progressive failure modes can therefore be explained. This generalized fatigue theory is validated against experimental results on a model pier bent which was tested at the SUNY testing facility. Good agreement between the theoretically predicted behavior and observed performance is obtained.