| 词条 | Bascule bridge | ||||||||||||||||
| 释义 |
|type_name= Bascule bridge |image=MovableBridge_draw.gif |image_title=This animation shows the movement of a double-leaf bascule. |sibling_names= Lift bridge, swing bridge |descendent_names= None |ancestor_names= Drawbridge, Plate girder bridge, cantilever bridge |carries= Pedestrian, automobile, truck, light rail, heavy rail |span_range= Short |material= Steel |movable= Yes |design= Medium |falsework= Site and prefabrication specific |}} A bascule bridge (sometimes referred to as a drawbridge) is a moveable bridge with a counterweight that continuously balances a span, or "leaf", throughout its upward swing to provide clearance for boat traffic. It may be single- or double-leafed. The name comes from the French term for balance scale, which employs the same principle. Bascule bridges are the most common type of movable span because they open quickly and require relatively little energy to operate, while providing the possibility for unlimited vertical clearance for marine traffic. HistoryBascule bridges have been in use since ancient times. However, it was not until the adoption of steam power in the 1850s that very long, heavy spans could be moved quickly enough for practical application. Types{{redirect|Strauss bascule|the company started by its inventor|Joseph Strauss (engineer)#Early career and the bascule bridge}}There are three types of bascule bridge designs,[1] and counterweights required to balance a bascule's span may be located either above or below the bridge deck. The fixed-trunnion (sometimes a "Chicago" bascule) rotates around a large axle that raises the span(s). The Chicago bascule name derives from the location where it is widely used, and is a refinement by Joseph Strauss of the fixed-trunnion.[2] The {{vanchor|rolling lift}} trunnion (sometimes a "Scherzer" rolling lift), raises the span by rolling on a track resembling a rocking chair base. The "Scherzer" rolling lift is a refinement patented in 1893 by the American engineer William Donald Scherzer.[3] The rarer Rall type combines rolling lift with longitudinal motion on trunnions when opening.[4] It was patented (1901) by Theodor Rall.[2][4][5] One of the few surviving examples is the Broadway Bridge (1913), in Portland, Oregon.[4][6] {{clear}}ExamplesSee also
References{{Commons category|Bascule bridges}}1. ^{{cite book | last=Koglin | first=Terry L. | title=Movable bridge engineering | url=https://books.google.com/books?id=_cyqkMJ7QDgC | accessdate=May 25, 2009 | year=2003 | publisher=John Wiley and Sons | isbn=978-0-471-41960-0 | chapter=4. Bascule Bridges | chapterurl=https://books.google.com/books?id=_cyqkMJ7QDgC&printsec=frontcover&cad=0#PPA33,M1 | ref=| postscript=.}} {{Bridge footer}}{{DEFAULTSORT:Bascule Bridge}}2. ^1 {{cite web|title=Landmark Designation Report: Historic Chicago Bridges|origyear=September 2006|date=September 2007|publisher=Commission on Chicago Landmarks|format=PDF| url=http://www.cityofchicago.org/dam/city/depts/zlup/Historic_Preservation/Publications/Historic_Chicago_Railroad_Bridges.pdf |pages=12, 15 (pdf pages 14, 17)|accessdate=April 21, 2013}} 3. ^{{cite patent |country=US |number=511713 |status=grant |title=Lift-Bridge |pubdate= |gdate=26 December 1893 |fdate=29 May 1893 |pridate= |inventor=Scherzer, William |invent1= |invent2= |assign1= |assign2= |class= |url=}} 4. ^1 2 {{cite book | last=Wood Wortman | first=Sharon |author2=Wortman, Ed | title=The Portland Bridge Book (3rd Edition) | publisher=Urban Adventure Press | year=2006 | pages=32, 35 | isbn=0-9787365-1-6 }} 5. ^{{cite web|title=Patent number 669348: T. Rall movable bridge|year=1901|publisher=United States Patent and Trademark Office (referenced online by Google Patents)|url=http://www.google.com/patents/US669348|accessdate=April 21, 2013}} 6. ^{{cite web|author=Historic American Engineering Record|title=Broadway Bridge, Spanning Willamette River at Broadway Street [sic], Portland, Multnomah County, OR|publisher=Library of Congress|url=https://www.loc.gov/pictures/item/or0292/|accessdate=April 21, 2013}} 2 : Bridges by structural type|Bascule bridges |
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