REPORT

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Publication Number: FHWA-HRT-09-028 Date: May 2009

Publication Number: FHWA-HRT-09-028
Date: May 2009

Hydrodynamic Forces on Inundated Bridge Decks

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FOREWORD

The Hydrodynamic Forces on Inundated Bridge Decks Study described in this report was conducted at the Federal Highway Administration's (FHWA) Turner-Fairbank Highway Research Center (TFHRC) J. Sterling Jones Hydraulics Laboratory and at the Department of Energy's Argonne National Laboratory's (Argonne) Transportation Research and Analysis Computing Center (TRACC). The study was in response to a request of several State transportation departments asking for new design guidance to predict hydrodynamic forces on bridge decks for riverine conditions. The study included experiments (physical modeling) at the TFHRC J. Sterling Jones Hydraulics Laboratory and High Performance Computational Fluid Dynamics (CFD) modeling at the Argonne National Laboratory. This report will be of interest to hydraulic engineers and bridge engineers who are involved in estimating loads for bridge decks. This report is being distributed as an electronic document through the TFHRC Web site (www.fhwa.dot.gov/research/tfhrc/).

Cheryl Allen Richter

Acting Director, Office of Infrastructure

Research and Development

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation 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.

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Technical Report Documentation Page

1. Report No. FHWA-HRT-09-028	2. Government Accession No.		3 Recipient's Catalog No.
4. Title and Subtitle Hydrodynamic Forces on Inundated Bridge Decks			5. Report Date May 2009
			6. Performing Organization Code
7. Author(s) Kornel Kerenyi, Tanju Sofu, and Junke Guo			8. Performing Organization Report No.
9. Performing Organization Name and Address GKY and Associates, Inc. 4229 Lafayette Center Dr., Suite 1850 Chantilly, VA 20151 University of Nebraska 312 N. 14th Street Alexander Building West Lincoln, NE 68588-0430			10. Work Unit No. (TRAIS)
			11. Contract or Grant No. DTFH-04-C-00037
12. Sponsoring Agency Name and Address Office of Infrastructure Research and Development Federal Highway Administration 6300 Georgetown Pike McLean, VA 22101-2296			13. Type of Report and Period Covered Laboratory Report November 2005-June 2008
			14. Sponsoring Agency Code FHWA Task Order 16
15. Supplementary Notes Contracting Officer's Technical Representative (COTR): Kornel Kerenyi, HRDI-07 Lars Hanson summarized the results and described the procedures used in this study. Afzal Bushra, Zhaoding Xie, and Oscar Berrios provided invaluable assistance with instrumentation, data collection, and analysis.
16. Abstract The hydrodynamic forces experienced by an inundated bridge deck have great importance in the design of bridges. Specifically, the drag force, lift force, and the moment acting on the bridge deck under various levels of inundation and a range of flow conditions influence the design and construction of the bridge. This report explores the forces acting on bridges in two ways. First, through physical experimentation on scaled-down bridge deck models tested in a flume and then with computational fluid dynamics (CFD) simulation models. Three bridge deck prototypes were used for the experimentation: a typical six-girder highway bridge deck, a three-girder deck, and a streamlined deck designed to better withstand the hydraulic forces. The forces (expressed as nondimensional force coefficients) on each of the bridge deck shapes were measured in the laboratory with an ultra-precise force balance under a range of inundation scenarios (including partial inundation) and at four different velocities characterized by Froude numbers in the range of 0.16 to 0.32. CFD modeling was performed using both the Fluent^® and STAR-CD^®software packages. The CFD models were calibrated to the flow conditions of the six-girder bridge, and these same conditions were used for the other two bridge shapes. A range of model options were tested including two-dimensional versus three-dimensional models, different mesh resolutions, boundary conditions, and turbulence models; their effect on the accuracy of results and processing efficiency were noted. Fitting equations were generated to create an envelope around the experimental data and create design charts for each of the bridge types and force coefficients. Finally, the CFD models, though they can match some of the general behavior of experimental models in terms of the relationship between inundation ratio and force measured at the bridge, do not yet faithfully reproduce the critical values of the hydraulic forces and show very little response to velocity. The CFD simulations seem promising as a method to test bridge designs, but more research is needed before complex designs can be tested wholly in the CFD realm. However, the design charts from the experimental results should be a valuable tool for the bridge designer in a wide range of design applications.
17. Key Words Hydrodynamic Forces, Force Balance, CFD, Inundated bridge decks		18. Distribution Statement No restrictions. This document is available to the public through the National Technical Information Service (NTIS), Springfield, VA 22161.
19. Security Classification (of this report) Unclassified	20. Security Classification (of this page) Unclassified		21. No. of Pages 44	22. Price

Form DOT F 1700.7

Reproduction of completed page authorized

SI (Modern Metric) Conversion Factors

1. Introduction

2. Theory and approach

3. Computational Fluid Dynamics Setup and Validation

4. Results

5. Deck force calculation examples

6. conclusion

List of Figures

Figure 1. Diagram. Scaled six-girder bridge deck model used in assessments of drag and lift forces and the nomenclature for bridge deck and flume dimensions

Figure 2. Equation. Inundation ratio

Figure 3. Equation. Froude number

Figure 4. Diagram. Definition sketch of forces acting on bridge deck

Figure 5. Equation. Drag coefficient

Figure 6. Equation. Lift coefficient

Figure 7. Equation. Moment coefficient

Figure 8. Diagram. Dimensions of the six-girder bridge deck

Figure 9. Diagram. Dimensions of the three-girder bridge deck

Figure 10. Diagram. Dimensions of the streamlined bridge deck

Figure 11. Diagram. Side view of railings with dimensions for the six-girder and three-girder bridge decks

Figure 12. Diagram. Test section of deck force analyzer showing strain gauge configuration

Figure 13. Photo. Deck force analyzer system at the TFHRC hydraulics lab

Figure 14. Image. Comparison of flow fields for the 2-D and 3-D models for the STAR-CD^® simulations

Figure 15. Image. Segment of bridge used for 3-D model

Figure 16. Diagram. Coarse meshes for STAR-CD^® simulation

Figure 17. Diagram. Partially refined meshes for STAR-CD^® simulation

Figure 18. Model. A rendering of the 3-D six-girder bridge deck in Fluent^®

Figure 19. Image. Velocity profile from the 2-D Fluent^® model

Figure 20. Image. Velocity profile from the 3-D Fluent^® model

Figure 21. Diagram. Fluent^® unstructured mesh in the vicinity of the bridge

Figure 22. Image. Velocity profile from the Fluent^® κ-ε CFD model for the six-girder bridge

Figure 23. Image. PIV velocity profile for the six-girder bridge

Figure 24. Image. Velocity profile from the Fluent^® κ-ε CFD model for the three-girder bridge

Figure 25. Image. PIV velocity profile for the three-girder bridge

Figure 26. Image. Velocity profile from the Fluent^® κ-ε CFD model for the streamlined bridge

Figure 27. Image. PIV velocity profile for the streamlined bridge

Figure 28. Graph. Drag coefficient versus inundation ratio for the six-girder bridge

Figure 29. Graph. Lift coefficient versus inundation ratio for the six-girder bridge

Figure 30. Graph. Moment coefficient versus inundation ratio for the six-girder bridge

Figure 31. Graph. Drag coefficient versus inundation ratio for the three-girder bridge

Figure 32. Graph. Lift coefficient versus inundation ratio for the three-girder bridge

Figure 33. Graph. Moment coefficient versus inundation ratio for three-girder bridge

Figure 34. Graph. Drag coefficient versus inundation ratio for streamlined bridge deck

Figure 35. Graph. Lift coefficient versus inundation ratio for the streamlined bridge

Figure 36. Graph. Moment coefficient versus inundation ratio for the streamlined bridge

Figure 37. Equation. Drag coefficient fitting equation for three- and six-girder bridges

Figure 38. Equation. Lift coefficient fitting equation for three- and six-girder bridges

Figure 39. Equation. Moment coefficient fitting equation for all bridge types

Figure 40. Equation. Drag coefficient fitting equation for the streamlined bridge

Figure 41. Equation. Lift coefficient fitting equation for the streamlined bridge

Figure 42. Equation. Upper fitting equation for drag coefficient as a function of h*

Figure 43. Equation. Total drag force per unit length on the example six-girder bridge for the 1,000-year flood

Figure 44. Equation. Velocity, v, at h*_crit

List of Tables

Table 1. Fitting equation coefficient values for six-girder (6-g) and three-girder (3-g) bridges

Table 2. Fitting equation coefficient values for the streamlined bridge

Table 3. Critical coefficient values by bridge type

Table 4. Bridge example dimensions

Table 5. Flow conditions for example design floods

Table 6. High and low force coefficients for the two example floods

List of Acronyms and Abbreviations

2-D	Two-dimensional
3-D	Three-dimensional
ADV	Acoustic Doppler Velocimeter
Argonne	Department of Energy's Argonne National Laboratory
CFD	Computational fluid dynamics
FHWA	Federal Highway Administration
LES	Large Eddy Simulation
PISO	Pressure-Implicit Split-Operator
PIV	Particle Image Velocimetry
PVC	Polyvinyl Chloride
R&D	Research and Development
RANS	Reynolds-averaged Navier-Stokes
SIMPLE	Semi-Implicit Method for Pressure Linked Equations
TFHRC	Turner-Fairbank Highway Research Center
TRACC	Transportation Research and Analysis Computing Center
VoF	Volume of fluid

List of Symbols

C_D	Drag coefficient
C_L	Lift coefficient
C_M	Moment coefficient
F_D	Drag force
F_L	Lift force
Fr	Froude number
g	Gravitational acceleration
h*	Inundation ratio
h*_crit	Critical Inundation ratio resulting in maximum forces
h_b	Height from bottom of flume to bottom of bridge
h_u	Height of water from bottom of flume
κ-ε	Turbulence model
L	Bridge length
M_cg	Moment about the center of gravity
Re	Reynolds number
s	Deck thickness
V, v	Free stream velocity
W	Bridgewidth
ρ	Fluid density (or water density)

Page Owner: Office of Research, Development, and Technology, Office of Infrastructure, RDT

Topics: research, infrastructure, structures, bridge hydraulics, scour
Keywords: Bridge decks, bridge design, bridge foundations, bridge hydraulics, bridge inundation, bridge scour, pressure flows, pressure scour, submerged flows
Scheduled Update: Archive - No Update needed

This page last modified on 07/18/2012