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Tied-arch
A tied-arch bridge is an arch bridge in which the outward horizontal forces of the arch(es) caused by tension at the arch ends to a foundation are countered by equal tension of its own gravity plus any element of the total deck structure such great arch(es) support. The arch(es) have strengthened chord(s) that run to a strong part of the deck structure or to independent tie-rods below the arch ends. Description Thrusts downwards on a tied-arch bridge deck are translated, as tension, by vertical ties between the deck and the arch, tending to flatten it and thereby to push its tips outward into the abutments, like for other arch bridges. However, in a tied-arch or bowstring bridge, these movements are restrained not by the abutments but by the strengthened chord, which ties these tips together, taking the thrusts as tension, rather like the string of a bow that is being flattened. Therefore, the design is also called a bowstring-arch or bowstring-girder bridge. The elimination ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tied-arch Bridge Pattern
A tied-arch bridge is an arch bridge in which the outward horizontal forces of the arch(es) caused by tension at the arch ends to a foundation are countered by equal tension of its own gravity plus any element of the total deck structure such great arch(es) support. The arch(es) have strengthened chord(s) that run to a strong part of the deck structure or to independent tie-rods below the arch ends. Description Thrusts downwards on a tied-arch bridge deck are translated, as tension, by vertical ties between the deck and the arch, tending to flatten it and thereby to push its tips outward into the abutments, like for other arch bridges. However, in a tied-arch or bowstring bridge, these movements are restrained not by the abutments but by the strengthened chord, which ties these tips together, taking the thrusts as tension, rather like the string of a bow that is being flattened. Therefore, the design is also called a bowstring-arch or bowstring-girder bridge. The elimination o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arch Bridge
An arch bridge is a bridge with abutments at each end shaped as a curved arch. Arch bridges work by transferring the weight of the bridge and its loads partially into a horizontal thrust restrained by the abutments at either side. A viaduct (a long bridge) may be made from a series of arches, although other more economical structures are typically used today. History Possibly the oldest existing arch bridge is the Mycenaean Arkadiko Bridge in Greece from about 1300 BC. The stone corbel arch bridge is still used by the local populace. The well-preserved Hellenistic Eleutherna Bridge has a triangular corbel arch. The 4th century BC Rhodes Footbridge rests on an early voussoir arch. Although true arches were already known by the Etruscans and ancient Greeks, the Romans were – as with the vault and the dome – the first to fully realize the potential of arches for bridge construction. A list of Roman bridges compiled by the engineer Colin O'Connor featur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Through Arch Bridge
A through arch bridge, also known as a through-type arch bridge, is a bridge that is made from materials such as steel or reinforced concrete, in which the base of an arch structure is below the deck but the top rises above it. It can either be lower bearing or mid-bearing. Thus, the deck is within the arch, and cables or beams that are in tension suspend the central part of the deck from the arch. Function For a specific construction method, especially for masonry arches, the proportions of the arch remain similar no matter what the size: wider arches are thus required to be taller arches. For a semi-circular arch, the height is half of the span. Bridges across deep, narrow gorges can have their arch placed entirely beneath a flat roadway, but bridges in flatter country rise above their road approaches. A wide bridge may require an arch so tall as to become a significant obstacle and incline for the roadway. Small bridges can be hump-backed, but larger bridges such as the Old B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fremont Bridge (Portland)
The Fremont Bridge is a steel tied-arch bridge over the Willamette River located in Portland, Oregon, United States. It carries Interstate 405 and US 30 traffic between downtown and North Portland where it intersects with Interstate 5. It has the longest main span of any bridge in Oregon and is the second longest tied-arch bridge in the world (after Caiyuanba Bridge across the Yangtze River, China). The bridge was designed by Parsons, Brinckerhoff, Quade and Douglas, and built by Murphy Pacific Corporation. The bridge has two decks carrying vehicular traffic, each with four lanes. The upper deck is signed westbound on US 30 and southbound on I-405. The lower deck is signed eastbound on US 30 and northbound on I-405. Design and construction Due to the public's dissatisfaction with the appearance of the Marquam Bridge, the Portland Art Commission was invited to participate in the design process of the Fremont. The improvement in visual quality resulted in a bridge that was ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Federal Highway Administration
The Federal Highway Administration (FHWA) is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program and the Federal Lands Highway Program. Its role had previously been performed by the Office of Road Inquiry, Office of Public Roads and the Bureau of Public Roads. History Background The organization has several predecessor organizations and complicated history. The Office of Road Inquiry (ORI) was founded in 1893. In 1905, that organization's name was changed to the Office of Public Roads (OPR) which became a division of the United States Department of Agriculture. The name was changed again to the Bureau of Public Roads in 1915 and to the Public Roads Administration (PRA) in 1939. It was then shifted to the Federal Works Agency which was abolished in 1949 when its name reverted to Bureau of Public Roads under the Department of Commerce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Truss
A truss is an assembly of ''members'' such as beams, connected by ''nodes'', that creates a rigid structure. In engineering, a truss is a structure that "consists of two-force members only, where the members are organized so that the assemblage as a whole behaves as a single object". A "two-force member" is a structural component where force is applied to only two points. Although this rigorous definition allows the members to have any shape connected in any stable configuration, trusses typically comprise five or more triangular units constructed with straight members whose ends are connected at joints referred to as ''nodes''. In this typical context, external forces and reactions to those forces are considered to act only at the nodes and result in forces in the members that are either tensile or compressive. For straight members, moments (torques) are explicitly excluded because, and only because, all the joints in a truss are treated as revolutes, as is necessary for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Truss Bridge
A truss bridge is a bridge whose load-bearing superstructure is composed of a truss, a structure of connected elements, usually forming triangular units. The connected elements (typically straight) may be stressed from tension, compression, or sometimes both in response to dynamic loads. The basic types of truss bridges shown in this article have simple designs which could be easily analyzed by 19th and early 20th-century engineers. A truss bridge is economical to construct because it uses materials efficiently. Design The nature of a truss allows the analysis of its structure using a few assumptions and the application of Newton's laws of motion according to the branch of physics known as statics. For purposes of analysis, trusses are assumed to be pin jointed where the straight components meet, meaning that taken alone, every joint on the structure is functionally considered to be a flexible joint as opposed to a rigid joint with strength to maintain its own shape, and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Twin Bridges
Twin bridges are a set of two bridges running parallel to each other. A pair of twin bridges is often referred to collectively as a twin-span or dual-span bridge. Twin bridges are independent structures and each bridge has its own superstructure#bridges, superstructure, Substructure (engineering), substructure, and Foundation (engineering), foundation. Bridges of this type are often created by building a new bridge parallel to an existing one in order to increase the traffic capacity of the crossing. While most twin-span bridges consist of two identical bridges, this is not always the case. For a bridge owner, twin bridges can improve the maintenance and management of the structures. For motorists, twin bridges can limit the risk that both directions of traffic will be disrupted by an accident. Examples *Carquinez Bridge – original cantilever span built in 1927 and later twinned in 1958; a newer suspension span was built in 2003 to replace the original 1927 span, which was l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nielsen Bridge
Nielsen may refer to: Business * Nielsen Gallery, an American commercial art gallery * Nielsen Holdings, global information, data, and measurement company ** Nielsen Corporation, a marketing research firm ** Nielsen Audio, formerly Arbitron, which measures radio listenership ** Nielsen Broadcast Data Systems, a service also known as BDS that tracks monitored radio, television, and internet airplay of songs ** Nielsen Media Research, the company that creates the Nielsen ratings *** Nielsen ratings, a rating system used to gauge audience measurement of television programming habits in the United States * Nielsen Norman Group, a computer user interface and user experience consulting firm Other uses * Nielsen (surname), including a list of people * Nielsen (crater), a lunar impact crater on the Oceanus Procellarum * Nielsen–Olesen vortex, a point-like object localized in two spatial dimensions or a classical solution of field theory with the same property * Nielsen fixed-point theor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infinity Bridge
The Infinity Bridge is a public pedestrian and cycle footbridge across the River Tees in the borough of Stockton-on-Tees in northern England. The bridge is situated one kilometre downriver of Stockton town centre, between the Princess of Wales Bridge and the Tees Barrage. It connects the Teesdale Business Park and the University of Durham's Queen's Campus in Thornaby-on-Tees on the south bank of the Tees with the Tees Valley Regeneration's £320 million North Shore development on the north bank. Built at a cost of £15 million with funding from Stockton Borough Council, English Partnerships and its successor body the Homes and Communities Agency, One NorthEast, and the European Regional Development Fund the bridge is a major part of the North Shore Redevelopment Project undertaken by Tees Valley Regeneration. The bridge had the project title ''North Shore Footbridge'' before being given its official name ''Infinity Bridge'', chosen by a panel of representatives from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
