1、Guide Specifications for Wind Loads on Bridges During Construction1st edition 2017AASHTO Publication Code: GSWLB-1ISBN: 978-1-56051-651-4American Association of State Highway and Transportation Officials 444 North Capitol Street, NW, Suite 249 Washington, DC 20001 202-624-5800 phone/202-624-5806 fax
2、 www.transportation.org Cover photos: Top Left: Spruce Street Interchange, Hillsborough County, Florida. Photo provided by Dennis Golabek. Top Right: U.S. 331 over Choctawhatchee Bay, Walton County, Florida. Photo provided by Andre Pavlov, Florida, DOT. Bottom: SR 30 at Cody Avenue, Hurlburt Field,
3、Florida. Photo provided by Mike Lenga, Stantec Consulting Services. 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. 2017 by the American Association of State Highway and Transportation Officials.All ri
4、ghts reserved. Duplication is a violation of applicable law.AASHTO EXECUTIVE COMMITTEE 20162017 Voting Members OFFICERS: PRESIDENT: David Bernhardt, Maine* VICE PRESIDENT: John Schroer, Tennessee* SECRETARY-TREASURER: Carlos Braceras, Utah EXECUTIVE DIRECTOR: Bud Wright, Washington, D. C. REGIONAL R
5、EPRESENTATIVES: REGION I: Leslie Richards, Pennsylvania Pete Rahn, Maryland REGION II: Charles Kilpatrick, Virginia James Bass, Texas REGION III: Randall S. Blankenhorn, Illinois Patrick McKenna, Missouri REGION IV: Carlos Braceras, Utah Mike Tooley, Montana IMMEDIATE PAST PRESIDENT: vacant *Elected
6、 at the 2016 Annual Meeting in Boston, Massachusetts Nonvoting Members Executive Director: Bud Wright, Washington, DC 2017 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.HIGHWAY SUBCOMMITTEE ON BRIDGES AND S
7、TRUCTURES, 2016 GREGG FREDRICK, Chair BRUCE V. JOHNSON, Vice Chair JOSEPH L. HARTMANN, Federal Highway Administration, Secretary PATRICIA J. BUSH, AASHTO Liaison ALABAMA, Eric J. Christie, William “Tim” Colquett, Randall B. Mullins ALASKA, Richard A. Pratt ARIZONA, David B. Benton, David L. Eberhart
8、, Pe-Shen Yang ARKANSAS, Charles “Rick” Ellis CALIFORNIA, Susan Hida, Thomas A. Ostrom, Dolores Valls COLORADO, Behrooz Far, Stephen Harelson, Jessica Martinez CONNECTICUT, Timothy D. Fields DELAWARE, B arry A. Benton, Jason Hastings DISTRICT OF COLUMBIA, Donald L. Cooney, Konjit C. “Connie” Eskende
9、r, Richard Kenney FLORIDA, Sam Fallaha, Dennis William Potter, Jeff Pouliotte GEORGIA, Bill DuVall, Steve Gaston HAWAII , James Fu IDAHO, Matthew Farrar ILLINOIS, Tim A. Armbrecht, Carl Puzey INDIANA, Anne M. Rearick IOWA , Ahmad Abu-Hawash, Norman L. McDonald KANSAS, Mark E. Hoppe, John P. Jones KE
10、NTUCKY, Mark Hite, Marvin Wolfe LOUISIANA, Arthur DAndrea, Paul Fossier, Zhengzheng “Jenny” Fu MAINE, Jeffrey S. Folsom, Wayne Frankhauser, Michael Wight MARYLAND, Earle S. Freedman, Jeffrey L. Robert, Gregory Scott Roby MASSACHUSETTS, Alexander K. Bardow, Thomas Donald, Joseph Rigney MICHIGAN, Matt
11、hew Jack Chynoweth, David Juntunen MINNESOTA, Arielle Ehrlich, Kevin Western MISSISSIPPI, Austin Banks, Justin Walker, Scott Westerfield MISSOURI, Dennis Heckman, Scott Stotlemeyer MONTANA, Kent M. Barnes, David F. Johnson NEBRASKA, Mark Ahlman, Fouad Jaber, Mark J. Traynowicz NEVADA, Troy Martin, J
12、essen Mortensen NEW HAMPSHIRE, David L. Scott , Peter Stamnas NEW JERSEY , Xiaohua “Hannah” Cheng, Nagnath “Nat” Kasbekar, Eli D. Lambert NEW MEXICO , Ted L. Barber, Raymond M. Trujillo, Jeff C. Vigil NEW YORK , Wahid Albert, Richard Marchione NORTH CAROLINA, Brian Hanks, Scott Hidden, Thomas Koch N
13、ORTH DAKOTA, Terrence R. Udland OHIO, Alexander B.C. Dettloff, Timothy J. Keller OKLAHOMA, Steven Jacobi, Walter Peters OREGON, Bruce V. Johnson, Tanarat Potisuk, Hormoz Seradj PENNSYLVANIA, James M. Long, Thomas P. Macioce, Lou Ruzzi PUERTO RICO, (Vacant) RHODE ISLAND, Georgette Chahine SOUTH CAROL
14、INA, Barry W. Bowers, Terry B. Koon, Jeff Sizemore SOUTH DAKOTA, Steve Johnson TENNESSEE, John S. Hastings, Wayne J. Seger TEXAS, Bernie Carrasco, Jamie F. Farris, Gregg A. Freeby U.S. DOT, Joseph L. Hartmann UTAH, Carmen Swanwick, Cheryl Hersh Simmons, Joshua Sletten VERMONT, James LaCroix, Wayne B
15、. Symonds VIRGINIA, Prasad L. Nallapaneni, Kendal R. Walus WASHINGTON , Tony M. Allen, Thomas E. Baker, Bijan Khaleghi WEST VIRGINIA , Ahmed Mongi, Billy Varney WISCONSIN , Scot Becker, William C. Dreher, William Olivia WYOMING , Paul G. Cortez, Gregg C. Frederick, Michael E. Menghini GOLDEN GATE BR
16、IDGE, HIGHWAY AND TRANSPORTATION DISTRICT, Kary H. Witt MDTA, Dan Williams N.J. TURNPIKE AUTHORITY, Richard J. Raczynski N.Y. STATE BRIDGE AUTHORITY, Jeffrey Wright PENN. TURNPIKE COMMISSION, James Stump U.S. ARMY CORPS OF ENGINEERSDEPARTMENT OF THE ARMY, Phillip W. Sauser, Christopher H. Westbrook
17、U.S. COAST GUARD, Kamal Elnahal U.S. DEPARTMENT OF AGRICULTUREFOREST SERVICE, John R. Kattell KOREA, Eui-Joon Lee, Sang-Soon Lee SASKATCHEWAN, Howard Yea TRANSPORTATION RESEARCH BOARD, Waseem Dekelbab 2017 by the American Association of State Highway and Transportation Officials.All rights reserved.
18、 Duplication is a violation of applicable law.GUIDE SPECIFICATIONS FOR WIND LOADS ON BRIDGES DURING CONSTRUCTION i INTRODUCTION Wind load provisions in the AASHTO LFRD Bridge Design Specifications were developed for bridges after the deck is placed. Originally, these provisions traced their roots to
19、 research work performed in the early 1950s (Vincent, 1953). In 2015, AASHTO adopted new provisions for determining wind loads on bridges based on work by Wassef and Raggett (2014). The response of bridge structures to wind loads before the deck is placed is significantly different from that of the
20、completed bridges. The flow of wind around the structure and, thus, the wind pressure acting on individual girders is different. Another difference between bridges during construction and bridges in service is the short length of time expected between the erection of the girders and the placement of
21、 the deck. Wind maps used in AASHTO LFRD Bridge Design Specifications for bridges in service are based on 7 percent probability of exceedance in 50 years. During construction, the period between girder erection and the placement of the deck can be as short as a few weeks. For the same probability of
22、 exceedance, the wind speed decreases with the decrease of time period. The basic general wind pressure equation used by many design specifications is as follows: 2Z zDP V KGC= where: PZ= design wind pressure = constant related to the density of air V = wind speed at a set elevation (usually 10 m or
23、 33 ft) KZ =pressure exposure and elevation coefficient accounting for the effect of the elevation of the bridge or bridge component, site topography, and surrounding obstructions on wind speed G = gust effect factor accounting for the distribution of wind pressure on the surface and/or the dynamic
24、effects CD= drag coefficient accounting for the effect of the shape of the component on wind pressure During construction of a multi-girder bridge, the drag coefficient varies from one girder to the next. Following are some of the factors affecting the drag coefficient for any of the girders in the
25、cross section during the period between girder erection and deck placement: The Position of the Girder in the Girder Groupthe windward girder is usually subjected to higher wind loads than other girders. The second girder typically sees a negative pressure, i.e. the pressure is in opposite direction
26、 to the wind direction. Wind loads start increasing for the following girders and generally become similar for girders six and higher. Type of Girdersteel I -girders, concrete I-girders and box-girders have different drag coefficients Geometry of the Girder Cross-Sectionfor the same type of girder,
27、the geometry of the section affects the drag coefficient. For example, for the same I-girder depth, the drag coefficient varies with the variation in flange width. For box-girders, the drag coefficient is affected by the box width-to-depth ratio and by the slope of the webs. Ratio of girder spacing
28、to girder depth The Angle between the Plane Passing through the Top of Girder Webs and the HorizontalThe value of this angle depends on the roadway cross slope or superelevation. The difference in this angle affects the flow characteristics of the wind around the girders and the resulting wind press
29、ure. Regardless of the differences between bridges during construction and completed bridges, very little research was performed on bridges during construction. Consolazio et. al. (2013), Consolazio and Edwards (2014), and Wassef and Raggett (2014) performed wind tunnel testing to determine wind loa
30、ds on bridges during construction before the deck is placed. This work formed the basis for the design provisions presented herein. The proposed design provisions follow to a great degree the wind load design provisions specified in the AASHTO LRFD Bridge Design Specifications, but are modified to a
31、ccount for the difference between completed bridges and bridges during construction. 2017 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.ii GUIDE SPECIFICATIONS FOR WIND LOADS ON BRIDGES DURING CONSTRUCTION
32、This page has intentionally been left blank. 2017 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.GUIDE SPECIFICATIONS FOR WIND LOADS ON BRIDGES DURING CONSTRUCTION iii TABLE OF CONTENTS 1S COPE 1 2D EFINITIO
33、NS 2 3N OTATION . 3 4W IND LOAD. 4 4.1Exposure Conditions 4 4.1.1General 4 4.1.2Wind Speed . 4 4.1.3Wind Direction for Determining Wind Exposure Category 7 4.1.4Ground Surface Roughness Categories . 7 4.1.5Wind Exposure Categories 7 4.2Wind Load on Structures . 8 4.2.1General 8 4.2.2Loads on the Sup
34、erstructure 14 4.2.2.1Wind Loads on the Girders 14 4.2.2.2Wind Loads on Cross-Frames, Diaphragms and Braces 15 4.2.3Loads on the Substructure . 15 4.2.3.1Loads from the Superstructure 15 4.2.3.2Loads Applied Directly to the Substructure . 16 4.3Control of Wind- Induced Bridge Motions . 16 4.3.1Gener
35、al 16 4.3.2Peak Wind- Induced Motions . 17 4.3.3Control of Dynamic Responses . 18 5R EFERENCES 20 2017 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.GUIDE SPECIFICATIONS FOR WIND LOADS ON BRIDGES DURING CON
36、STRUCTION 1 1 SCOPE These guide specifications establish minimum requirements for wind loads on bridges during construction before the deck is placed. All other aspects of the design shall be performed in accordance to the AASHTO LRFD Bridge Design Specifications or as specified by the bridge owner,
37、 as appropriate. C.1 The wind loads determined using these specifications are to be used for checking bridge girders, temporary and permanent bracing, and the permanent substructure during the erection of the girders and up to the time of placement of the deck. In cases where temporary bridge works,
38、 such as temporary support towers, are used during construction, the wind transmitted from the superstructure to the temporary components should be used in the design of the latter. Except for determining the wind load from the superstructure transmitted to the temporary bridge works, all other aspe
39、cts of the design of temporary bridge works should be performed in accordance to AASHTO Guide Design Specifications for Bridge Temporary Works (2017). 2017 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.2 GU
40、IDE SPECIFICATIONS FOR WIND LOADS ON BRIDGES DURING CONSTRUCTION 2D EFINITIONS Active Work ZoneWork zone during the time workers are on- site and erection of the structure is in progress. Inactive Work Zone Work zone during the time construction work is not being performed, including time between wo
41、rk shifts and overnight, and the time between the erection of the girders and the placement of the deck. Temporary Bridge WorksTemporary components and structures used in the construction of bridges that are meant to be removed during or after the completion of the structure, such as construction to
42、wers and temporary substructures. 2017 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.GUIDE SPECIFICATIONS FOR WIND LOADS ON BRIDGES DURING CONSTRUCTION 3 3 NOTATION CD= drag coefficient (dim.) (4.2.1) (4.2.
43、2.1) D = the vertical dimension of the box-girder (ft) (4.3.2) (C4.3.2) E = Youngs Modulus (psi) (C4.3.2) G = gust effect factor (dim.) (4.2.1) g = gravitational acceleration: 32.2 (ft/s2) (C4.3.2) I = moment of inertia of the girder about the horizontal axis (ft4) (C4.3.2) KZ =pressure exposure and
44、 elevation coefficient (dim.) (4.2.1) (C4.2.1) (C4.2.3) KZ(B) = pressure exposure and elevation coefficient for Wind Exposure Category B (dim.) (4.2.1) (C4.2.1) (4.3.3) KZ(C) = pressure exposure and elevation coefficient for Wind Exposure Category C (dim.) (4.2.1) (C4.2.1) (4.3.3) KZ(D) = pressure e
45、xposure and elevation coefficient for Wind Exposure Category D (dim.) (4.2.1) (C4.2.1) (4.3.3) L = beam length (ft) (C4.3.2) n = fundamental vertical natural frequency of vibration of the box-girder (Hz) (4.3.2) (C4.3.2) PZ= design wind pressure (ksf) (4.2.1) (C4.2.2.1) R = wind speed reduction fact
46、or during construction (dim.) (4.2.1) U1000= mean 10-minute averaged wind speed with an approximate mean recurrence interval of 1000 years (mph) (4.3.3) U10000= mean 10-minute averaged wind speed with an approximate mean recurrence interval of 10,000 years (mph) (4.3.2) V = reference 3-second gust w
47、ind speed (mph) (4.1.2) (4.3.2) (C4.3.2) w = weight per unit length of beam (klf) (C4.3.2) Z = structure height (ft) (4.2.1) (C4.2.1) 2017 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.4 GUIDE SPECIFICATION
48、S FOR WIND LOADS ON BRIDGES DURING CONSTRUCTION 4 W IND LOAD 4.1 EXPOSURE CONDITIONS 4.1.1 General Wind pressure shall be assumed to be uniformly distributed on the area exposed to the wind. The exposed area shall be the area of the structure components, as seen in elevation taken perpendicular to t
49、he wind direction. The wind load shall be the product of the wind pressure and exposed area. The wind shall be assumed horizontal and can come from any horizontal direction. Areas that do not contribute to the extreme force effect under consideration may be neglected in the analysis. Structures shall be checked a
