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REPORT
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Publication Number:  FHWA-HRT-17-093    Date:  February 2018
Publication Number: FHWA-HRT-17-093
Date: February 2018

 

Adjacent Box Beam Connections: Performance and Optimization

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FOREWORD

With the ever-increasing congestion and deterioration of the Nation’s highway system, there is a need to develop highly durable and rapidly constructed infrastructure systems. Durable bridge structures that require less intrusive maintenance and exhibit longer life spans, thus maximizing the use of the facilities, are highly desirable. Expediting bridge construction can minimize traffic flow disruptions. The precast prestressed concrete box beam bridge is one type of bridge system that can be constructed in an accelerated process with wide applications in short- and medium-span bridges in the United States.

The study presented herein was completed as part of the Federal Highway Administration’s Structural Concrete Research Program. It investigated the connection design details for this type of bridge, including novel connection details whose performance surpasses common practice. The findings provide an innovative solution that could advance the state of the practice in bridge construction. An executive summary of the information contained in this report has been published as a TechBrief titled Adjacent Box Beam Connections: Performance and Optimization.(1) This report will be of interest to engineers, academics, researchers, and industry partners who are involved the design, fabrication, construction, or maintenance of short- and medium-span bridges.

Cheryl Allen Richter, Ph.D., P.E.
Director, Office of Infrastructure
Research and Development

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation (USDOT) in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document.

The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ names appear in this report only because they are considered essential to the objective of the document.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

TECHNICAL REPORT DOCUMENTATION PAGE
1. Report No.
FHWA-HRT-17-093
2. Government Accession No. 3. Recipient’s Catalog No.
4. Title and Subtitle
Adjacent Box Beam Connections: Performance and Optimization
5. Report Date
February 2018
6. Performing Organization Code:
7. Author(s)
Jiqiu Yuan, Benjamin A. Graybeal, and Kevin Zmetra
8. Performing Organization Report No.
9. Performing Organization Name and Address
Office of Infrastructure Research & Development
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101-2296
10. Work Unit No.
11. Contract or Grant No.
DTFH61-10-D-00017
12. Sponsoring Agency Name and Address
Office of Infrastructure Research & Development
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101-2296
13. Type of Report and Period Covered
Final Report; March 2013–September 2016
14. Sponsoring Agency Code
HRDI-40
15. Supplementary Notes
This report was developed by research staff at the Turner-Fairbank Highway Research Center. Jiqiu Yuan and Kevin Zmetra are contract researchers who support the Federal Highway Administration’s (FHWA) structural concrete research efforts, and Ben Graybeal of FHWA manages the FHWA Structural Concrete Research Program and leads the Bridge Engineering Research team.
16. Abstract
Precast prestressed concrete adjacent box beam bridges are widely utilized for short- and medium-span bridges throughout North America. However, a recurring issue with this bridge type is the deterioration of the shear key connection, resulting in substandard performance of the overall bridge system. This research investigated partial- and full-depth connection designs utilizing conventional non-shrink grout and ultra-high performance concrete (UHPC) by conducting full-scale structural testing. Quantitative measures to evaluate the connection performance that may assist in examining similar types of bridges are suggested in this study. A model to calculate the shear force in the connection is proposed, and both the shear and tensile stresses at the connection are analyzed. The findings can be used to assist in the design of connections for this bridge type. The performance of conventionally grouted and UHPC connections are presented and compared. It was found that the adjacent box beam bridges with UHPC connections can be a resilient bridge superstructure system, providing an innovative solution that can advance the state of the practice in bridge construction. This report corresponds to the accompanying TechBrief, Adjacent Box Beam Connections: Performance and Optimization.(1)
17. Key Words
Box beam bridge, Connection, Shear key design, Transverse post-tension, Transverse shear, Transverse tension, Ultra-high performance concrete, UHPC
18. Distribution Statement
No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161.
https://www.ntis.gov/
19. Security Classif. (of this report)
Unclassified
20. Security Classif. (of this page)
Unclassified
21. No. of Pages
129
22. Price
N/A

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized.

SI* (Modern Metric) Conversion Factors

TABLE OF CONTENTS

LIST OF FIGURES

LIST OF TABLES

LIST OF ABBREVIATIONS AND SYMBOLS

Abbreviations
AASHTO American Association of State Highway and Transportation Officials
EA exposed aggregate
FHWA Federal Highway Administration
LRFD Load and Resistance Factor Design
LVDT linear variable differential transformer
PT post-tensioning
SB sandblasted
UHPC ultra-high performance concrete
Symbols
b distance from each end support to each loading point
EI beam stiffness
EIeff effective beam stiffness
EIeff,δ effective beam stiffness based on deflection measurements
EIeff,ε effective beam stiffness based on strain measurements
f′c compressive strength of concrete
l span length
M moment at the mid-span
Mequivalent equivalent moment transferred through the connection
Mmax maximum moment transferred through the connection
P load at each load point
v′max maximum distributed shear force
Vy transverse shear distribution
V′y triangular shear distribution
y distance from where the tensile strain is measured to the neutral axis of the cross section
δ deflection at the mid-span
δA deflection of beam A at the mid-span
δAE deflection from the loaded beam on the exterior linear variable differential transformer
δAI deflection from the loaded beam on the interior linear variable differential transformer
δB deflection of beam B at the mid-span
δBE deflection from the unloaded beam on the exterior linear variable differential transformer
δBI deflection from the unloaded beam on the interior linear variable differential transformer
δcalculated calculated deflection of the beam
δmeasured measured deflection in beam B when beam A is loaded at the maximum load and beam B is loaded at the minimum level
Δδ differential deflection
ε longitudinal tensile strain at the mid-span
ε additional strain in beam B due to the equivalent moment
ε5kip strain in beam B when both beams are loaded at 5 kip (22 kN)
εA longitudinal tensile strain in beam A
εB longitudinal tensile strain in beam B
εcalculated calculated strain
εmeasured measured strain in beam B when beam A is loaded at the maximum load and beam B is loaded at the minimum load

Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000
Turner-Fairbank Highway Research Center | 6300 Georgetown Pike | McLean, VA | 22101