Spatial and Temporal Load Distribution in Steel Bridge Superstructures (Vol. I): Agency Survey and Preliminary Numerical Modeling of Skewed Steel I-Girder Bridges for Field Instrumentation

Zhou, Siang; Dorado, Ricardo; LaFave, James; Fahnestock, Larry

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https://hdl.handle.net/2142/131132 Copy

Description

Title

Spatial and Temporal Load Distribution in Steel Bridge Superstructures (Vol. I): Agency Survey and Preliminary Numerical Modeling of Skewed Steel I-Girder Bridges for Field Instrumentation

Author(s)

• Zhou, Siang
• Dorado, Ricardo
• LaFave, James
• Fahnestock, Larry

Issue Date

2026-02

Keyword(s)

• Skewed Bridge
• Steel I-Girder Bridge
• Flange Lateral Bending
• Field Monitoring
• Numerical Simulation
• Deck Placement
• Live Load
• Thermal Effect

Date of Ingest

2026-02-11T14:44:15-06:00

Abstract

Highly skewed steel I-girder bridges are used commonly across the US, especially in congested areas, despite complications in their analysis, design, and construction. Systematic investigation of skewed steel I-girder superstructure response, load distribution, and deformation through field monitoring and numerical simulation is needed, including analysis of bridges under construction, short-term live load, and long-term thermal and traffic loads. AASHTO’s load and resistance factor design specification allows for line girder analysis with defined live load distribution factors (considering effects of skew between 30° and 60°) when designing non-curved steel bridges. When considering lateral behavior of skewed bridges, AASHTO provides suggestions for design values of flange lateral bending stress in addition to line girder analysis when bridge skew exceeds 20° for certain cross-frame layouts. This skew limit is 45° in Illinois Department of Transportation’s “Bridge Design Manual.” When designing bridges for lateral bending during deck placement, AASHTO suggests equations to conservatively estimate flange lateral bending moments caused by eccentric loading from an overhang acting on an exterior girder top flange, in the absence of a refined analysis. Efficiency of the simplified design approaches and skew consideration in current standard design practice needs to be further evaluated through field monitoring and companion numerical studies. The research project partially described in this report was initiated in Illinois to investigate demands, load distribution, and static and dynamic responses of composite steel skewed I-girder bridge superstructures during construction and after bridges are in service. Two skewed steel I-girder bridges (41° and 45°), with stub and integral abutments, respectively, were studied through field monitoring and numerical simulations. This report documents the initial phases of the research: a survey to understand practices used and challenges faced by state transportation agencies when designing and constructing skewed steel I-girder bridges, information about and field instrumentation of the two monitored bridges, methods for 3D finite element analysis, and preliminary analysis conducted to guide field instrumentation planning of the bridges.

Publisher

Illinois Center for Transportation/Illinois Department of Transportation

Has Part

ISSN: 0197-9191

Series/Report Name or Number

FHWA-ICT-26-002

Type of Resource

text

Genre of Resource

technical report

Language

eng

DOI

https://doi.org/10.36501/0197-9191/26-002

Sponsor(s)/Grant Number(s)

IDOT-R27-194

Copyright and License Information

No restrictions. This document is available through the National Technical Information Service, Springfield, VA 22161.

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