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Wind-Induced Vibration of Stay Cables

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Wind-Induced Vibration of Stay Cables Wind-Induced Vibration of Stay Cables PUBLICATION NO. FHWA-HRT-05-083 AUGUST 2007 Research, Development, and Technology Turner-Fairbank Highway Research Center 6300 Georgetown Pike McLean, VA 22101-2296 Foreword Cable-stayed bridges have become the form of choice over the past several decades for bridges in the medium- to long-span range. In some cases, serviceability problems involving large amplitude vibrations of stay cables under certain wind and rain conditions have been observed. This study was conducted to develop a set of consistent design guidelines for mitigation of excessive cable vibrations on cable-stayed bridges. The project team started with a thorough review of existing literature; this review indicated that while the rain/wind problem is known in sufficient detail, galloping of dry inclined cables was the most critical wind-induced vibration mechanism in need of further experimental research. A series of wind tunnel tests was performed to study this mechanism. Analytical and experimental research was performed to study mitigation methods, covering a range of linear and nonlinear dampers and crossties. The study also included brief studies on live load-induced vibrations and establishing driver/pedestrian comfort criteria. Based on the above, design guidelines for the mitigation of wind-induced vibrations of stay cables were developed. As a precautionary note, the state of the art in stay cable vibration mitigation is not an exact science. These new guidelines are only intended for use by professionals with experience in cable-stayed bridge design, analysis, and wind engineering, and should only be applied with engineering judgment and due consideration of special conditions surrounding each project. Gary L. Henderson 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. This report does not constitute a standard, specification, or regulation. 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. 2. Government Accession No. 3. Recipient’s Catalog No. FHWA-RD-05-083 4. Title and Subtitle 5. Report Date Wind-Induced Vibration of Stay Cables August 2007 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Sena Kumarasena, Nicholas P. Jones, Peter Irwin, Peter Taylor 9. Performing Organization Name and Address 10. Work Unit No. Primary Consultant: HNTB Corporation 11. Contract or Grant No. 75 State St., Boston, MA 02109 DTFH61-99-C-00095 352 Seventh Ave., 6th Floor, New York, NY 10001-5012 In association with: John Hopkins University Dept. of Civil Engineering, Baltimore, MD 21218-2686 Rowan Williams Davies and Irwin, Inc. 650 Woodlawn Road West, Guelph, Ontario N1K 1B8 Buckland and Taylor, Ltd. Suite 101, 788 Harborside Drive, North Vancouver, BC V7P3R7 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Office of Infrastructure R&D Final Report Federal Highway Administration September 1999 to December 2002 6300 Georgetown Pike 14. Sponsoring Agency Code McLean, VA 22101-2296 15. Supplementary Notes Contracting Officer’s Technical Representative (COTR) Harold Bosch, HRDI-07 16. Abstract Cable-stayed bridges have become the form of choice over the past several decades for bridges in the medium- to long-span range. In some cases, serviceability problems involving large amplitude vibrations of stay cables under certain wind and rain conditions have been observed. This study was conducted to develop a set of consistent design guidelines for mitigation of excessive cable vibrations on cable-stayed bridges. To accomplish this objective, the project team started with a thorough review of existing literature to determine the state of knowledge and identify any gaps that must be filled to enable the formation of a consistent set of design recommendations. This review indicated that while the rain/wind problem is known in sufficient detail, galloping of dry inclined cables was the most critical wind-induced vibration mechanism in need of further experimental research. A series of wind tunnel tests was performed to study this mechanism. Analytical and experimental research was performed to study mitigation methods, covering a range of linear and nonlinear dampers and crossties. The study also included brief studies on live load-induced vibrations and establishing driver/pedestrian comfort criteria. Based on the above, design guidelines for mitigation of wind-induced vibrations of stay cables were developed. 17. Key Words 18. Distribution Statement cable-stayed bridge, cables, vibrations, wind, No restrictions. This document is available to the public through rain, dampers, crossties the National Technical Information Service, Springfield, VA 22161 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No of Pages 22. Price Unclassified Unclassified 281 Form DOT F 1700.7 (8-72) Reproduction of completed pages authorized SI* (MODERN METRIC) CONVERSION FACTORS APPROXIMATE CONVERSIONS TO SI UNITS Symbol When You Know Multiply By To Find Symbol LENGTH in inches 25.4 millimeters mm ft feet 0.305 meters m yd yards 0.914 meters m mi miles 1.61 kilometers km AREA in2 square inches 645.2 square millimeters mm2 ft2 square feet 0.093 square meters m2 yd2 square yard 0.836 square meters m2 ac acres 0.405 hectares ha mi2 square miles 2.59 square kilometers km2 VOLUME fl oz fluid ounces 29.57 milliliters mL gal gallons 3.785 liters L ft3 cubic feet 0.028 cubic meters m3 yd3 cubic yards 0.765 cubic meters m3 NOTE: volumes greater than 1000 L shall be shown in m3 MASS oz ounces 28.35 grams g lb pounds 0.454 kilograms kg T short tons (2000 lb) 0.907 megagrams (or "metric ton") Mg (or "t") TEMPERATURE (exact degrees) oF Fahrenheit 5 (F-32)/9 Celsius oC or (F-32)/1.8 ILLUMINATION fc foot-candles 10.76 lux lx fl foot-Lamberts 3.426 candela/m2 cd/m2 FORCE and PRESSURE or STRESS lbf poundforce 4.45 newtons N lbf/in2 poundforce per square inch 6.89 kilopascals kPa APPROXIMATE CONVERSIONS FROM SI UNITS Symbol When You Know Multiply By To Find Symbol LENGTH mm millimeters 0.039 inches in m meters 3.28 feet ft m meters 1.09 yards yd km kilometers 0.621 miles mi AREA mm2 square millimeters 0.0016 square inches in2 m2 square meters 10.764 square feet ft2 m2 square meters 1.195 square yards yd2 ha hectares 2.47 acres ac km2 square kilometers 0.386 square miles mi2 VOLUME mL milliliters 0.034 fluid ounces fl oz L liters 0.264 gallons gal m3 cubic meters 35.314 cubic feet ft3 m3 cubic meters 1.307 cubic yards yd3 MASS g grams 0.035 ounces oz kg kilograms 2.202 pounds lb Mg (or "t") megagrams (or "metric ton") 1.103 short tons (2000 lb) T TEMPERATURE (exact degrees) oC Celsius 1.8C+32 Fahrenheit oF ILLUMINATION lx lux 0.0929 foot-candles fc cd/m2 candela/m2 0.2919 foot-Lamberts fl FORCE and PRESSURE or STRESS N newtons 0.225 poundforce lbf kPa kilopascals 0.145 poundforce per square inch lbf/in2 *SI is the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. (Revised March 2003) ii TABLE OF CONTENTS EXECUTIVE SUMMARY .....................................................................................1 CHAPTER 1. INTRODUCTION...........................................................................5 BACKGROUND ....................................................................................................................... 5 PROJECT OBJECTIVES AND TASKS................................................................................ 7 CHAPTER 2. COMPILATION OF EXISTING INFORMATION ...................9 REFERENCE MATERIALS................................................................................................... 9 INVENTORY OF U.S. CABLE-STAYED BRIDGES .......................................................... 9 CHAPTER 3. ANALYSIS, EVALUATION, AND TESTING..........................11 MECHANICS OF WIND-INDUCED VIBRATIONS ........................................................ 11 Reynolds Number................................................................................................................ 11 Strouhal Number ................................................................................................................ 11 Scruton Number.................................................................................................................. 12 Vortex Excitation of an Isolated Cable and Groups of Cables....................................... 12 Rain/Wind-Induced Vibrations ......................................................................................... 13 Wake Galloping for Groups of Cables.............................................................................. 14 Galloping of Dry Inclined Cables .......................................................................................15
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