Fatigue in High Strength Reinforcement Bars: An Overview

Abstract

Fatigue is a process of progressive structural change in a material subjected to transient loads, stresses or strains. Fatigue strength is defined as the maximum transient stress range (S) that may be repeated without causing failure for a specified number of loading cycles (N). The stress range is defined as the algebraic difference between the maximum and the minimum stress in a stress cycle: S = fmax - fmin; that is: the transient stress. Most ferrous materials exhibit an ‘endurance limit’ or ‘fatigue limit’ below which failure does not occur for an unlimited number of cycles, N. High strength bars can optimize design and cost as a result of high strength concrete, shallower sections of concrete and shuttering; with smaller foundations to carry the smaller loads. It is noted that normal allowable design stress is not invalidated by fatigue considerations.

Keywords: Fatigue, endurance limit, stress range, ADTT, relative rib area, AASHTO, DL, ADTT_SL, ADT, tensile strength, welded wire fabric, yield strength, anchorage, offshore, salinity