bridge, card game
bridge, card game derived from whist whist, card game for four players, those on opposite sides of the table being partners. The full pack of 52 cards is dealt. The dealer's last card is turned up to indicate trump, and after he draws this card in hand, the player on the left of the dealer leads...... Click the link for more information. , played with 52 cards by four players in two partnerships.
Basic Rules
The cards in contract bridge rank from ace down to two; in bidding, suits rank spades, hearts, diamonds, and clubs. After all cards are dealt, so that each player holds 13 cards, the dealer begins the auction, which proceeds in rotation to the left. Each player must bid, pass, double (increase the value of the previously stated contract), or redouble (only after a double, further increasing the point value of the contract). A bid is an offer to win a stated number (over six) of tricks with a named suit as trump or with no trump. The lowest bid is one, the highest seven. Each bid, i.e., "one diamond," "one no-trump," "four hearts," must be higher than the preceding bid, with no-trump ranking above spades. Artificial bids are those that convey certain information to a partner and are not meant to be taken literally. The highest bid of the auction becomes the contract after three consecutive passes end the bidding. The player who first named the suit (or no-trump) specified in the winning bid becomes the declarer. The player to the left of the declarer leads any card face up, and the next hand, that of the declarer's partner, is placed face up on the table, grouped in suits. This is known as the dummy, and the declarer selects the cards to be played from this hand. The object of the game for both partnerships is to win as many tricks as possible, a trick being the three cards played in rotation after the lead. Suits must be followed, but a player who has no cards in the suit led may play any card. Highest trump or, if no trump card is played, highest card of the suit led wins. Points are awarded for the number of tricks won. Numerous conventions—generally accepted forms of bidding—are used in bridge, but the four standard ones are Blackwood, Gerber, Stayman, and grand-slam force.
Competitive Bridge
Duplicate bridge, in which the same prearranged hands are played by individuals, pairs, or teams of four, is the main form of competitive bridge. The laws of contract bridge are promulgated in the Western Hemisphere by the American Contract Bridge League, which holds various bridge tournaments. In international contract bridge matches the Bermuda bowl, the trophy for victory, is the emblem of the world championship. In Olympic years an olympiad championship is held by the World Bridge Federation and replaces the team tournament for the Bermuda bowl.
History
Bridge probably originated in the Middle East in the 19th cent. Auction bridge, one form of the game, was developed by the British in India and later was popular in England and the United States. It is still played but has largely been supplanted by contract bridge, which achieved popularity after important innovations were made in 1925 by Harold S. Vanderbilt. Its phenomenal popularity owed much to the activities of Ely Culbertson Culbertson, Ely (ē`lē kŭl`bərtsən), 1891–1955, American authority on contract bridge, b. Romania.
..... Click the link for more information. . The craze subsided but was later revived; books, tournaments, and newspaper columns on bridge abound. Culbertson devised the honor count system to evaluate a hand for bidding. The point count (or standard American) system introduced by Charles H. Goren in the 1940s has generally replaced honor count.
Bibliography
See C. H. Goren, Bridge Complete (rev. ed. 1971); T. Reese and A. Dormer, The Complete Book of Bridge (1974).
bridge, structure
bridge, structure built over water or any obstacle or depression to allow the passage of pedestrians or vehicles. See also viaduct viaduct (vī`ədŭkt') [Lat...... Click the link for more information. .
Early Bridges
In ancient times and among primitive peoples a log was thrown across a stream, or two vines or woven fibrous ropes (the upper for a handhold and the lower for a footwalk) were thrown across, to serve as a bridge. Later, arched structures of stone or brick were used; traces of these, built from 4000 to 2000 B.C., have been found in the E Mediterranean region. The Romans built long, arched spans, many of which are still standing. Bridges built during the Middle Ages usually rested on crude stone arches with heavy piers pier, in engineering, term applied to a mass of reinforced concrete or masonry supporting a large structure, such as a bridge. When piers are built on ground of poor bearing value, it is often necessary to drive piles to obtain a firm base.
..... Click the link for more information. (intermediate supports) that were a great obstruction to river traffic, and their roadways were often lined with small shops.
The best known early American design is the New England covered bridge, since wood was abundant and cheap, and did not demand trained masons. Colonial American bridge builders were willing to run the risk of rot or fire in exchange for such savings in time and manpower. Beginning with Abraham Darby's bridge at Coalbrookdale in 1779, most bridges began to be built of cast and wrought iron. Robert Stephenson, an English engineer, designed and built a bridge of this type across Menai Strait in North Wales (1850). Another is Victoria Bridge across the St. Lawrence at Montreal. The disadvantage of cast iron for bridges is its low tensile strength.
Modern Bridge Designs
There are six basic modern bridge forms: the beam, the truss, the arch, the cantilever, the cable-stay, and the suspension. A beam bridge is made of long timber, metal, or concrete beams anchored at each end. If the beams are arranged in a lattice, such as a triangle, so that each shares only a portion of the weight on any part of the structure, the result is a truss bridge. An arch bridge has a bowed shape causing the vertical force of the weight it carries to produce a horizontal outward force at its ends. It may be constructed of steel, concrete, or masonry. A cantilever cantilever (kăn`təlēvər), beam supported rigidly at one end to carry a load along the free arm or at the free end.
..... Click the link for more information. bridge is formed by self-supporting arms anchored at and projecting toward one another from the ends; they meet in the middle of the span where they are connected together or support a third member. In a cable-stayed bridge, the roadway is supported by cables attached directly to the supporting tower or towers. This differs from a suspension bridge, where the roadway is suspended from vertical cables that are in turn attached to two or more main cables. These main cables hang from two towers and have their ends anchored in bedrock or concrete.
The modern era of bridge building began with the development of the Bessemer process Bessemer process (bĕs`əmər) [for Sir Henry Bessemer ], industrial process for the manufacture of steel from molten pig iron.
..... Click the link for more information. for converting cast iron into steel. It became possible to design framed structures with greater ease and flexibility. Single-piece, rolled steel beams can support spans of 50 to 100 ft (15–30 m), depending on the load. Larger, built-up beams are made for longer spans; a steel box-beam bridge with an 850-ft (260-m) span crosses the Rhine at Cologne.
Truss, Arch, and Cantilever Bridges
The truss can span even greater distances and carry heavy loads; it is therefore commonly used for railroad bridges. A large truss span like that over the Columbia River at Astoria, Oreg., can extend to 1,232 ft (376 m). If the truss is shaped into an arch, even longer bridges are possible; the Bayonne Bridge between New York and New Jersey, the Sydney Harbor Bridge in Australia, and the New River Bridge in West Virginia are the longest steel arch bridges, at 1,675 ft (510 m), 1,670 ft (509 m), and 1,700 ft (518 m), respectively. Concrete arch bridges tend to be somewhat smaller, the largest being the Krk Bridge in Croatia and the Gladesville Bridge across the Parramatta River at Sidney, Australia, at 1,280 ft (390 m) and 1,000 ft (305 m), respectively; the longest concrete arch bridge in the United States is the Natchez Trace Parkway Bridge in Franklin, Tenn., at 582 ft (177 m). The cantilever, however, is more common for spans of such lengths. The cantilevered Forth Bridge (1890) in Scotland was the first major structure built entirely of steel, the material that made possible its two record-setting spans of 1,710 ft (521 m) each. They remained the longest in existence until 1917, when the St. Lawrence River at Quebec Bridge was built; it has an 1,800-ft (549-m) span. The longest cantilever bridge in the United States is the Commodore John Barry Bridge in Chester, Penn., which has an 1,644 ft (501 m) span.
Cable-Stayed, Suspension, and Combination Bridges
The cable-stayed bridge is the most modern type, coming into prominence during the 1950s. The longest is the Tatara Bridge in Ehime, Japan, which has a 2,920 ft (890 m) span. The Ponte de Normandie in Le Havre, France, spans 2,808 ft (856 m); the Second Yangtze Bridge in Nanjing, China, spans 2,060 ft (628 m); and the Third Yangtze Bridge in Wuhan, China, spans 2,028 ft (618 m). The longest cable-stayed bridge in the United States is the Dame Point Bridge in Jacksonville, Fla., which has a span of 1,300 ft (396 m).
The suspension bridge is used for the longest spans. The earliest suspension bridges built in America were those constructed by the American builder James Finley. The design of suspension bridges advanced when J. A. Roebling Washington Augustus Roebling, 1837–1926, b. Saxonburg, Pa., grad. Rensselaer Polytechnic Institute, 1857, had aided his father in building the Allegheny Suspension Bridge.
..... Click the link for more information. , a German-born engineer who emigrated to the United States, developed the use of wire cables and stiffening trusses. His first completed suspension bridge spanned the Niagara River in 1854. He also designed the Brooklyn Bridge Brooklyn Bridge, vehicular suspension bridge, New York City, southernmost of the bridges across the East River, between lower Manhattan and Brooklyn; built 1869–83. The achievement of J. A. Roebling and his son W. A. Roebling, it has a span of 1,595.
..... Click the link for more information. across the East River (completed 1883), which was the world's longest suspension bridge at the time of its construction, having a main span of 1,595.5 ft (487 m).
Today the longest spans in the world are suspended. The longest main spans are the Akashi Kaikyo Bridge, Hyogo, Japan, 6,529 ft (1,990 m); Izmit Bay Bridge, Marmara Sea, Turkey, 5,472 ft (1,668 m); Store Bælt Bridge, Denmark, 5,328 ft (1,624 m); Humber River Bridge, Hull, England, 4,626 ft (1410 m); Tsing Ma Bridge, Hong Kong, 4,518 ft (1,377 m); Verrazano-Narrows Bridge Verrazano-Narrows Bridge, vehicular suspension bridge, New York City, across the Narrows at the entrance to New York harbor, linking the boroughs of Brooklyn and Staten Island. Designed by O. H. Ammann , the bridge was completed in 1964.
..... Click the link for more information. , New York City, 4,260 ft (1,298 m); Golden Gate Bridge Golden Gate Bridge, across the Golden Gate from San Francisco to Marin Co., W Calif.; built 1933–37. Its overall length is 9,266 ft (2,824 m); its main span across the strait, 4,200 ft (1,280 m), is one of the longest bridges in the world. Joseph B.
..... Click the link for more information. , San Francisco, 4,200 ft (1,280 m); Hoga Kusten (or High Coast) Bridge, Västernörrland, Sweden, 3,969 ft (1,210 m); Mackinac Straits Bridge, Mich., 3,800 ft (1,158 m); Minami Bisan-Seto Bridge, Japan, 3,668 ft (1,118 m); Second Bosporus Bridge, İstanbul, Turkey, 3,576 ft (1,090 m); First Bosporus Bridge, İstanbul, Turkey, 3,524 ft (1,074 m); and George Washington Bridge George Washington Bridge, vehicular suspension bridge across the Hudson River, between Manhattan borough of New York City and Fort Lee, N.J.; constructed 1927–31. It is one of the longest suspension bridges in the world.
..... Click the link for more information. , New York City, 3,500 ft (1,067 m).
Combination spans are often used to bridge even longer stretches of water. The San Francisco–Oakland Bay Bridge San Francisco–Oakland Bay Bridge, double-decked structure, W Calif.; built 1933–36. It has a total length of 8.25 mi (13.2 km). From San Francisco it crosses the bay to Yerba Buena Island, where a tunnel connects with spans leading to Oakland and Berkeley.
..... Click the link for more information. , noted for its three long spans, of which two are suspension spans and the third a cantilever, has a total length of 8.25 mi (13.2 km). The Chesapeake Bay Bridge-Tunnel Chesapeake Bay Bridge-Tunnel, officially the Lucius J. Kellam, Jr. Bridge-Tunnel, 17.6 mi (28.2 km) long, across the mouth of Chesapeake Bay, E Va., connecting Cape Charles with Norfolk, Va.
..... Click the link for more information. has two 1-mi (1.6-km) tunnels along its 17.6-mi (28.2-km) length, and the 8-mi (12.9-km) Confederation Bridge Confederation Bridge, Fr. Pont de la Confédération, bridge that joins Borden-Carleton in Prince Edward Island with Cape Jourimain in New Brunswick, Canada. Spanning the Northumberland Strait at its narrowest point, the bridge measures 8 mi (12.
..... Click the link for more information. , linking Prince Edward Island to the Canadian mainland, consists of three bridges. The longest combination spans are the twin Lake Ponchartrain Causeways near New Orleans, Louisiana, whose parallel roadways stretch nearly 24 mi (38 km).
Movable Bridges
Movable bridges are generally constructed over waterways where it is impossible or prohibitive to build a fixed bridge high enough for water traffic to pass under it. The most common types of movable bridge are the lifting, bascule, and swing bridges. The lifting bridge, or lift bridge, consists of a rigid frame carrying the road and resting abutments, over each of which rises a steel-frame tower. The center span, which in existing bridges is as long as 585 ft (178 m), is hoisted vertically. The bascule bridge follows the principle of the ancient drawbridge. It may be in one span or in two halves meeting at the center. It consists of a rigid structure mounted at the abutment on a horizontal shaft, about which it swings in a vertical arc. The lower center span of the famous Tower Bridge in London is of the double-leaf bascule type. Because of the need for large counterweights and the stress on hoisting machinery, bascule bridge spans are limited to about 250 ft (75 m). The swing bridge is usually mounted on a pier in midstream and swung parallel to the stream to allow water passage.
Military Bridges
In wartime, where the means of crossing a stream or river is lacking or a bridge has been destroyed by the enemy, the military bridge plays a vital role. Standard types of military bridges include the trestle, built on the spot by the engineering corps from any available material, and the floating bridge made with portable pontoons pontoon, one of a number of floats used chiefly to support a bridge, to raise a sunken ship, or to float a hydroplane or a floating dock. Pontoons have been built of wood, of hides stretched over wicker frames, of copper or tin sheet metal sheathed over wooden
..... Click the link for more information. .
Bibliography
See D. Plowden, The Spans of North America (1984); H. Petroski, Engineers of Dreams: Great Bridge Builders and the Spanning of America (1995); J. Dupré and F. O. Geary, Bridges: A History of the World's Most Famous and Important Spans (1996); S. A. Ostrow, Bridges (1997); F. Gottemoeller, Bridgescape: The Art of Designing Bridges (1998); K. Willard, Bridges: Designing the Future (1999). See also bibliographies for articles on individual bridges.
bridge
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bridge
Card game similar to whist. Bridge is any one of several games, including games such as auction bridge and contract bridge, which retain the essential features of whist: Four players participate, two against two in partnership. They play with a 52-card pack, all cards of which are dealt face downward one at a time, clockwise. When play begins, the object is to win tricks, consisting of one card from each player in rotation. The players must, if able, contribute a card of the suit led, and the trick is won by the highest card. All tricks taken in excess of the first six tricks are known as odd tricks. Before play begins, a suit may be designated the trump suit, in which case any card in it beats any card of the other suits. In all types of bridge a certain number points are needed to win a game, and two games won by the same team allows them to win the rubber.
bridge
(1) To cross from one circuit, channel or element over to another.
(2) See Wi-Fi bridge and wireless bridge.
(3) A device that connects two LAN segments together, which may be similar or dissimilar, such as Ethernet and Token Ring. A bridge is inserted in the network to keep traffic contained within the segments to improve performance. By monitoring which station acknowledged receipt of the address, bridges learn which nodes belong to the segment and maintain their own address tables. Multiport bridges have more than two ports and perform a switching function just like a LAN switch.
Bridges Vs. Routers
Bridges work at layer 2 and are not protocol dependent. Routers work at layer 3 and are protocol dependent. Bridges are faster than routers because they do not have to glean routing information. See LAN, transparent bridge, repeater, router, gateway and hub. See also conference bridge.
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bridge1
www.worldbridge.org
bridge2
www.worldbridge.org
Bridge
bridge [brij]
Bridge
A structure built to provide ready passage over natural or artificial obstacles, or under another passageway. Bridges serve highways, railways, canals, aqueducts, utility pipelines, and pedestrian walkways. In many jurisdictions, bridges are defined as those structures spanning an arbitrary minimum distance, generally about 10–20 ft (3–6 m); shorter structures are classified as culverts or tunnels. In addition, natural formations eroded into bridgelike form are often called bridges. This article covers only bridges providing conventional transportation passageways.
Bridges generally are considered to be composed of three separate parts: substructure, superstructure, and deck. The substructure or foundation of a bridge consists of the piers and abutments which carry the superimposed load of the superstructure to the underlying soil or rock. The superstructure is that portion of a bridge or trestle lying above the piers and abutments. The deck or flooring is supported on the bridge superstructure; it carries and is in direct contact with the traffic for which passage is provided.
Bridges are classified in several ways. Thus, according to the use they serve, they may be termed railway, highway, canal, aqueduct, utility pipeline, or pedestrian bridges. If they are classified by the materials of which they are constructed (principally the superstructure), they are called steel, concrete, timber, stone, or aluminum bridges. Deck bridges carry the deck on the very top of the superstructure. Through bridges carry the deck within the superstructure. The type of structural action is denoted by the application of terms such as truss, arch, suspension, stringer or girder, stayed-girder, composite construction, hybrid girder, continuous, cantilever, or orthotropic (steel deck plate).
The two most general classifications are the fixed and the movable. In the former, the horizontal and vertical alignment of the bridge are permanent; in the latter, either the horizontal or vertical alignment is such that it can be readily changed to permit the passage beneath the bridge of traffic. Movable bridges are sometimes called drawbridges in an anachronistic reference to an obsolete type of movable bridge spanning the moats of castles.
A singular type of bridge is the floating or pontoon bridge, which can be a movable bridge if it is designed so that a portion of it can be moved to permit the passage of water traffic.
The term trestle is used to describe a series of short spans supported by braced towers, and the term viaduct is used to describe a high structure of short spans, often of arch construction.
Fixed bridges
This type of construction is selected when the vertical clearance provided beneath the bridge exceeds the clearance required by the traffic it spans. For very short spans, construction may be a solid slab or a number of beams; for longer spans, the choice may be girders or trusses. Still longer spans may dictate the use of arch construction, and if the spans are even longer, stayed-girder bridges are used. Suspension bridges are used for the longest spans.
Beam bridges consist of a series of beams, usually of rolled steel, supporting the roadway directly on their top flanges. The beams are placed parallel to traffic and extend from abutment to abutment. Plate-girder bridges are used for longer spans than can be practically traversed with a beam bridge. In its simplest form, the plate girder consists of two flange plates welded to a web plate, the whole having the shape of an I. Box-girder bridges have steel girders fabricated by welding four plates into a box section. A conventional floor beam and stringer can be used on box-girder bridges, but the more economical arrangement is to widen the top flange plate of the box so that it serves as the deck. When this is done, the plate is stiffened to desired rigidity by closely spaced bar stiffeners or by corrugated or honeycomb-type plates. These stiffened decks, which double as the top flange of the box girders, are termed orthotropic. The wearing surface on such bridges is usually a relatively thin layer of asphalt.
Truss bridges, consisting of members vertically arranged in a triangular pattern, can be used when the crossing is too long to be spanned economically by simple plate girders. Where there is sufficient clearance underneath the bridge, the deck bridge is more economical than the through bridge because the trusses can be placed closer together, reducing the span of the floor beams.
The continuous bridge is a structure supported at three or more points and capable of resisting bending and shearing forces at all sections throughout its length. The bending forces in the center of the span are reduced by the bending forces acting oppositely at the piers. Trusses, plate girders, and box girders can be made continuous. The advantages of a continuous bridge over a simple-span bridge (that is, one that does not extend beyond its two supports) are economy of material, convenience of erection (without need for falsework), and increased rigidity under traffic. The disadvantages are its sensitivity to relative change in the levels of supporting piers, the difficulty of constructing the bridge to make it function as it is supposed to, and the occurrence of large movements at one location due to thermal changes.
The cantilever bridge consists of two spans projecting toward each other and joined at their ends by a suspended simple span. The projecting spans are known as cantilever arms, and these, plus the suspended span, constitute the main span. The cantilever arms also extend back to shore, and the section from shore to the piers offshore is termed the anchor span. Trusses, plate girders, and box girders can be built as cantilever bridges. The chief advantages of the cantilever design are the saving in material and ease of erection of the main span. The cable-stayed bridge, a modification of the cantilever bridge which has come into modern use, resembles a suspension bridge. It consists of girders or trusses cantilevering both ways from a central tower and supported by inclined cables attached to the tower at the top or sometimes at several levels.
The suspension bridge is a structure consisting of either a roadway or a truss suspended from two cables which pass over two towers and are anchored by backstays to a firm foundation. If the roadway is attached directly to the cables by suspenders, the structure lacks rigidity, with the result that wind loads and moving live loads distort the cables and produce a wave motion on the roadway. When the roadway is supported by a truss which is hung from the cable, the structure is called a stiffened suspension bridge. The stiffening truss distributes the concentrated live loads over a considerable length of the cable.
Since the development of the prestressing method, bridges of almost every type are being constructed of concrete. Prior to the advent of prestressing, these bridges were of three types: (1) arches, which were built in either short or long spans; (2) slab bridges of quite short spans, which were simply reinforced concrete slabs extending from abutment to abutment; and (3) deck girder bridges, consisting of concrete slabs built integrally with a series of concrete girders placed parallel to traffic. The advent of prestressed concrete greatly extended the utility and economy of concrete for bridges, particularly by making the hollow box-girder type practicable. See Prestressed concrete
Movable bridges
Modern movable bridges are either bascule, vertical lift, or swing; with few exceptions, they span waterways. They are said to be closed when set for the traffic they carry, and open when set to permit traffic to pass through the waterway they cross. Bascule and swing bridges provide unlimited vertical clearance in the open position. The vertical clearance of a lift bridge is limited by its design.
The bascule bridge consists primarily of a cantilever span, which may be either a truss or a plate girder, extending across the channel. Bascule bridges rotate about a horizontal axis parallel with the waterway. The portion of the bridge on the land side of the axis, carrying a counterweight to ease the mechanical effort of moving the bridge, drops downward, while the forward part of the leaf opens up over the channel much like the action of a playground seesaw. Bascule bridges may be either single-leaf, where rotation of the entire leaf over the waterway is about one axis on one side of the waterway, or double-leaf, where the leaves over the waterway rotate about two axes on opposite sides of the waterway.
The vertical-lift bridge has a span similar to that of a fixed bridge and is lifted by steel ropes running over large sheaves at the tops of its towers to the counterweights, which fall as the lift span rises and rise as it falls. If the bridge is operated by machinery on each tower, it is known as a tower drive. If it is driven by machinery located on the lift span, it is known as a span drive.
Swing bridges revolve about a vertical axis on a pier, called the pivot pier, in the waterway. There are three general classes of swing bridges: the rim-bearing, the center-bearing, and the combined rim-bearing and center-bearing. Rim-bearing bridges are supported on circular girder drums on rollers, center-bearing on a single large bearing at the center of rotation.
Substructure
Bridge substructure consists of those elements that support the trusses, girders, stringers, floor beams, and decks of the bridge superstructure. Piers and abutments are the primary bridge substructure elements. Other types of substructure, such as skewbacks for arch bridges, pile bents for trestles, and various forms of support wall, are also commonly used for specific applications.
Degradation
Many factors can cause bridges to degrade and become structurally deficient and in need of repair. Two environmental factors that cause significant damage to primarily concrete components in bridges are excessive changes in temperature and freeze-thaw cycles in the presence of moisture. Steel structures are vulnerable to corrosion, especially in prolonged moisture environments. Use of deicing salts on concrete pavements and bridge decks produces chemical reactions that accelerate the corrosion of reinforcing steel. A significant cause of bridge damage is vehicular impact and fatigue from repeated truck loads. Special loads, such as seismic, wind, and snow, also may produce dramatic degradation of bridge structures. See Mechanical vibration
Strengthening techniques
The strengthening of concrete bridges is generally achieved by replacing the damaged material, incorporating additional structural members, as in external prestressing, or increasing the size and capacity of existing members.
Repair techniques
Numerous repair techniques have evolved for concrete members in both bridges and buildings for replacing damaged concrete, repairing cracks, and repairing corroded reinforced steel bars. Steel bridges are most often strengthened by the addition of new steel members or smaller elements. Steel welding and bolting are well-developed techniques for steel connections. Thus, strengthening of steel bridges is perhaps more defined than for the concrete bridges. Techniques for repairing steel bridge elements include flame straightening, hot mechanical straightening, cold mechanical straightening, welding, bolting, partial replacement and complete replacement.
Bridge
| 1. | BRIDGE - A component of ICES for civil engineers. [Sammet 1969, p. 616]. | ||
| 2. | (networking, hardware) | bridge - A device which forwards traffic between
network segments based on data link layer information.
These segments would have a common network layer address. Every network should only have one root bridge. See also gateway, router. |
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