SYMPOSIA PAPER Published: 01 January 1976
STP33374S

Fatigue Crack Growth Under Variable-Amplitude Loading in Various Bridge Steels

Source

Well-conceived procedures used to study the safety and reliability of structures recognize that the performance of a structure or a structural component is governed not only by material properties but also by the design, fabrication, inspection, erection, and use of the structure. These parameters govern the initiation of subcritical cracks and their propagation to critical dimensions, and therefore, determine the useful fatigue life of structural components subjected to load fluctuations.

This paper presents the results of the first phase of an investigation sponsored by the National Cooperative Highway Research Program, Project 12-14, to study “Subcritical Crack Growth in Steel Bridge Members.”

The paper describes the fatigue-crack-growth behavior of various bridge steels (A36, A588-A, A588-B, A514-B, A514-E, and A514-F) under variable-amplitude random-sequence stress spectra such as occur in actual bridges. The fatigue crack growth-rate data were obtained by using wedge-opening-loading specimens tested under variable-amplitude random-sequence load spectra that are represented by a Rayleigh distribution function.

The data obtained for these steels showed that the average fatigue crack growth rates, da/dN, under variable-amplitude random-sequence load fluctuation and under constant-amplitude load fluctuation agreed closely when da/dN was plotted as a function of the root-mean-square stress intensity factor range, ΔKrms. Thus, within the limits of the present investigation, the average fatigue crack-growth rates, da/dN, of various bridge steels subjected to variable-amplitude random-sequence load fluctuations, such as occur in actual bridges and to constant-amplitude load fluctuations, can be represented by the equation dadN=A(ΔKrms)n where ΔKrms is the root-mean-square stress intensity factor fluctuation, and A and n are material constants.

Author Information

Barsom, JM
Research Laboratory, United States Steel Corporation, Monroeville, Pa.
Price: $25.00
Contact Sales
Related
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Details
Developed by Committee: E08
Pages: 217–232
DOI: 10.1520/STP33374S
ISBN-EB: 978-0-8031-4672-3
ISBN-13: 978-0-8031-0344-3