Details:

Creators:
Helwig, Todd ; Egilmez, Ozgur ; Jetann, Charles
Helwig, Todd ; Egilmez, Ozgur ; Jetann, Charles Less -
Corporate Creators:
University of Houston
Corporate Contributors:
Texas. Dept. of Transportation. Research and Technology Transfer Section ; United States. Federal Highway Administration
Texas. Dept. of Transportation. Research and Technology Transfer Section ; United States. Federal Highway Administration Less -
Subject/TRT Terms:
[+]
Bracing Bridge Construction Computer Models Finite Element Method Girders Laboratory Tests Permanent Metal Deck Forms Steel Bridges
Publication/ Report Number:
Research Report 4145-1
Resource Type:
Tech Report
Geographical Coverage:
United States
TRIS Online Accession Number:
01650945
Edition:
Final Report
Corporate Publisher:
Texas. Dept. of Transportation
Abstract:
Lateral torsional buckling is a failure mode that often controls the design of steel bridge girders during construction. Bracing in the form of cross-frames and diaphragms are often provided at locations along the bridge length to reduce the unbraced length and increase the buckling capacity. Although they are not currently relied upon for bracing, permanent metal deck forms (PMDF) are frequently used to support the wet concrete for the bridge deck during construction. Similar forms used in the building industry are commonly relied upon for beam bracing. The forms typically behave as a shear diaphragm that restrains the warping deformation in the top flange. The main difference between the forms used in the building and bridge industries are the method of connection. In the building industry, the forms are typically fastened directly to the top girder flange by the shear studs, puddle welds or other mechanical connections. In the bridge industry, the forms are supported on a coldformed angle that allows the contractor to adjust the form elevation to account for variations in the flange thickness or differential camber between adjacent girders. The support angles lead to eccentric connections that substantially reduce the stiffness of the PMDF systems. The objective of the research outlined in this report is to improve the understanding of the bracing behavior of PMDF systems used in the bridge industry as well as developing improved connection details between the support angles and the girder flanges. The research included laboratory tests and finite element analytical (FEA) modeling. The laboratory studies included shear tests, full scale testing of a twin girder system with a 50 ft. span. Both lateral load tests and buckling tests were conducted on the twin girder system with PMDF for bracing. In addition to demonstrating the behavior of the bracing systems, the laboratory studies were also used to validate the computer models of the bracing systems so that parametric FEA studies could be conducted. Modified details for the connection angles consisted of stiffening angles that span between adjacent girders at intermediate locations along the girder length. The stiffening angles substantially increased the stiffness of the PMDF system The modified details make PMDF systems a viable bracing alternative in steel bridges that can significantly reduce the number of cross-frames and diaphragms required for stability bracing.
Format:
PDF
Funding:
Research Study 0-4145
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:d74ce0fae38a7c06f3f19c0c6f9d92e0d26068df60802c12b23ba6733cbcc2d8
Download URL:
https://rosap.ntl.bts.gov/view/dot/34237/dot_34237_DS1.pdf
File Type:

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