Determination of U-Bolt Connection Load Capacities in ...

Determination of U-Bolt Connection Load Capacities in Overhead Sign Support Structures

Final Report June 2019

Sponsored by Iowa Department of Transportation (InTrans Project 18-638)

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Technical Report Documentation Page

1. Report No. InTrans Project 18-638

2. Government Accession No.

4. Title and Subtitle

Determination of U-Bolt Connection Load Capacities in Overhead Sign Support Structures

3. Recipient's Catalog No.

5. Report Date June 2019 6. Performing Organization Code

7. Author(s)

Brent M. Phares (0000-0001-5894-4774) and Zhengyu Liu (0000-0002-7407-0912)

9. Performing Organization Name and Address

Bridge Engineering Center Iowa State University 2711 South Loop Drive, Suite 4700 Ames, IA 50010-8664

12. Sponsoring Organization Name and Address

Iowa Department of Transportation 800 Lincoln Way Ames, IA 50010

8. Performing Organization Report No. InTrans Project 18-638

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

13. Type of Report and Period Covered Final Report 14. Sponsoring Agency Code

15. Supplementary Notes

Visit intrans.iastate.edu for color pdfs of this and other research reports.

16. Abstract

The load capacities of the U-bolt connections used in steel overhead sign trusses for the Iowa Department of Transportation (DOT) are not known because the bolts are used in ways that do not match the available manufacturer data. Although these Ubolt connections appear to have performed satisfactorily in the past, there has been a growing safety concern in recent years because of the need for overhead sign trusses to support larger signs at greater span lengths.

The objective of this project was to develop effective and efficient methodologies to realistically estimate the capacity of the Ubolt connections specified in the actual steel overhead sign truss (SOST) design standards. To achieve this objective, a comprehensive literature search on the utilization and modeling techniques for U-bolt connections was first conducted. Three laboratory tests were then conducted on two types of specimens with loading directions of 0? and 90? for the Type-A specimen and 0? for the Type-B specimen.

The data collected from the tests were used to calibrate the finite element model. The calibrated model was then used in a parametric study to calculate the yield and ultimate capacity of both types of specimens with various material properties and load resultant directions.

Finally, interaction diagrams were developed with limitations for design usage to estimate the capacity of the U-bolt connections with different material types and load directions.

17. Key Words

finite element modeling--highway sign trusses--interaction diagrams-- overhead sign supports--parametric study--U-bolt load capacity

19. Security Classification (of this 20. Security Classification (of this

report)

page)

Unclassified. Form DOT F 1700.7 (8-72)

Unclassified.

18. Distribution Statement No restrictions.

21. No. of Pages 22. Price

70

NA

Reproduction of completed page authorized

DETERMINATION OF U-BOLT CONNECTION LOAD CAPACITIES IN OVERHEAD SIGN SUPPORT STRUCTURES

Final Report June 2019

Principal Investigator Brent M. Phares, Research Associate Professor Bridge Engineering Center, Iowa State University

Research Assistant Zhengyu Liu, Research Engineer Bridge Engineering Center, Iowa State University

Authors Brent M. Phares and Zhengyu Liu

Sponsored by Iowa Department of Transportation

Preparation of this report was financed in part through funds provided by the Iowa Department of Transportation

through its Research Management Agreement with the Institute for Transportation (InTrans Project 18-638)

A report from Bridge Engineering Center

Iowa State University 2711 South Loop Drive, Suite 4700

Ames, IA 50010-8664 Phone: 515-294-8103 / Fax: 515-294-0467

intrans.iastate.edu

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