Three Case Histories of Cracking Problems Associated with Steel Bridge Floor Beams

Walker, W.H.; Holbrook, M.D.; Cassity, P.A.

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https://hdl.handle.net/2142/14187 Copy

Description

Title

Three Case Histories of Cracking Problems Associated with Steel Bridge Floor Beams

Author(s)

• Walker, W.H.
• Holbrook, M.D.
• Cassity, P.A.

Issue Date

1992-06

Keyword(s)

• highway bridges
• Floorbeams
• Fatigue
• fracture

Abstract

Floor system cracking problems, the focus of the present study, occur in both structures of recent construction and in older bridges which have been in service for many years. The present study has risen out of specific cases of floor system cracks which are not immediately detrimental to the structural integrity of the floor system and which do not at the outset seem related to a usual design basis load effects. The cases forming the central focus of this report are: (1) The 1-474 Shade-Lohmann Bridge over the Illinois River south of Peoria, (2) The 1-74 Bridge over the Vermilion River at Danville, and (3) The 1-74 Bridge over the Sangamon near Mahomet in Champaign County. The following is seen: Case 1: Cracking due to forces not associated with vertical vehicle loading. That is, evidence is strong that cracking arises from longitudinal load transmitted through the out of plane flexure of the floor beam web in the segment between the connection clip angles and the flange at either end. Calculations show that a very modest induced longitudinal deformation is associated with substantialloca1 stresses at the web to flange junction which is the site of the cracking. Case 2: Fatigue failure of a detail with adverse geometry but with forces induced by vehicle loads which clearly account for the damage. A repair detail to reduce member forces has been suggested and is evaluated. Case 3: The development of a fatigue crack at a cope detail associate with a reasonable stress state for the damage observed, but with poor correlation with a limited controlled vehicle test and predictions of bridge behavior using a grid model. Additional field studies with more extensive instrumentation and a more comprehensive analytical model is needed to resolve uncertainties in this case.

Publisher

University of Illinois Engineering Experiment Station. College of Engineering. University of Illinois at Urbana-Champaign.

Series/Report Name or Number

Civil Engineering Studies SRS-569

Type of Resource

text

Language

en

Permalink

http://hdl.handle.net/2142/14187

Sponsor(s)/Grant Number(s)

• Department of Transportation. State of Illinois.
• The U.S. Department of Transportation, Federal Highway Administration.
• Contract IHR-312

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