Measurement and Analysis of Distortion-Induced Fatigue in Multigirder Steel Bridges
Publication: Journal of Bridge Engineering
Volume 8, Issue 2
Abstract
Fatigue damage to multigirder steel bridges on skew can result from distortion caused by differential deflection of adjacent girders that impose out-of-plane bending of girder web gaps. Existing design procedures give recommendations to mitigate the effects of distortional fatigue but do not directly address secondary, out-of-plane deformations, nor do they provide guidance in determining the magnitude of out-of-plane stresses in girder webs. An experimental study was conducted to (1) implement a field monitoring program for a typical multigirder steel bridge on skew supports; (2) assess the frequency and magnitude of distortional fatigue stresses at web-stiffener connections; and (3) evaluate the impact of these stresses on fatigue life. Measurements from twelve strain gauges were continuously monitored and recorded for a period exceeding three months on Minnesota Department of Transportation Bridge #27734. Web-gap stresses in negative-moment regions were found to be much larger than flange stresses. The results of a detailed finite-element study indicate that actual strains at the web gaps may be much larger than the values measured at the strain gauge locations. This study also revealed the mechanism of web-gap distortion, suggesting an approximate method for predicting web-gap stress based on known girder differential deflection.
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Information & Authors
Information
Published In
Journal of Bridge Engineering
Volume 8 • Issue 2 • March 2003
Pages: 84 - 91
Copyright
Copyright © 2003 American Society of Civil Engineers.
History
Received: Oct 31, 2000
Accepted: Apr 9, 2002
Published online: Feb 14, 2003
Published in print: Mar 2003
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