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Title:

A Study of Stiffness of Steel Bridge Cross Frames

Authors:

by Weihua Wang

Published:

2013

Austin, Texas

University of Texas at Austin

Type:

Online document

1 PDF (xix, 231 pages)

Online Access:

https://repositories.lib.utexas.edu/handle/2152/21...

Access Note:

Web page with download option(s)

Summary

Cross frames are critical components in steel bridge systems. Cross frames brace girders against lateral torsional buckling and assist in distributing live loads to girders during the service life of the bridge. In curved bridges, cross frames also serve as primary structural members in resisting torsion generated by the traffic loads. The conventional cross frames are often constructed in X- or K- type shapes with steel angle sections. However, the actual stiffness of these cross frames are not well understood or quantified, leading to potentially inaccurate prediction of bridge behavior and safety during construction and in service. Previous studies have shown the possibility of employing new sections, such as tubular members and double angles, in cross frame designs. In addition, a type-Z cross frame, or single diagonal cross frame was also found to be a potential use to simplify the design. However, the effectiveness of these innovative cross frame types has not been completely examined. And these new cross frames have yet compared with the conventional ones in terms of their stiffness and strength capacity. This dissertation documents the results of a study on the stiffness of various types of cross frame systems. Full size cross frames were tested to establish actual stiffness of the cross frames specimens. The tests results revealed a significant discrepancy between the actual measured stiffness and the stiffness calculated using methods commonly employed by bridge designers. The research showed that the major source of this discrepancy was eccentricity in the connection. The stiffness reduction was quantified by employing analytical derivation and finite element modeling. As a result, methods were developed to account for the stiffness reduction.

Publ. Place

Austin, Texas

Contents

Chapter 1. Introduction (Conventional Cross Frame; Single-Diagonal Cross Frames) --
Chapter 2. Background (Lateral Torsional Buckling; Bracing Requirements; Fundamentals of Beam Bracing; Beam Bracing Stiffness; Equivalent Stiffness of Cross Frames; Stiffness Reduction Due to the Eccentric Connection; Beam Bracing Strength) --
Chapter 3. Laboratory Tests (Test Setup; Cross Frame Test Program; Single Angle X-frame; Single Angle K-frame; Square Tube Z-frame; Double Angle Z-frame; Single Angle Z-frame; Coupon Tension Tests) --
Chapter 4. Computer Models for Cross Frame Stiffness (Truss Model; Shell Element Model; Results of Computer Models) --
Chapter 5. Analytical Solution for Stiffness Reduction --
Chapter 6. FEA Parametric Studies for Stiffness of Single Angle X-frame --
Chapter 7. FEA Parametric Studies for Stiffness of Single Angle K-frame --
Chapter 8. Impact of Stiffness Reduction on Cross Frame Design and Bridge Behavior --
Chapter 9. Conclusions and Recommendations --
Appendix. Coupon Test Results

Notes

"August 2013"
• Doctor of Philosophy
• Thesis supervisor: Todd A. Helwig; Co-supervisor: Michael D. Engelhardt

Print Copy

Collection:

Theses Online Only

Call Number:

Wang, W. 2013 Diss.

OCLC No.

858450900

More Like This

Topics

Bridge construction
Bridges
Curved bridges
Finite element method
Frames
Girder bridges
Mechanical stability
Steel
Steel bridges
Stiffness

Related to

• Cited in 2023 NCHRP Report 1045, "Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections." https://library.ctr.utexas.edu/Presto/catalogid=40984

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