San Francisco Oakland Bay Bridge Retrofit 3

A lattice girder is a

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 assembla ...

girder A girder () is a support beam used in construction. It is the main horizontal support of a structure which supports smaller beams. Girders often have an I-beam cross section composed of two load-bearing ''flanges'' separated by a stabilizing ...

where the load is carried by a web of latticed metal.

Overview

The lattice girder was used prior to the development of larger rolled steel plates. It has been supplanted in modern construction with

welded Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as braz ...

bolted The BOLT Browser was a web browser for mobile phones including feature phones and smartphones that can run Java ME applications. The BOLT Browser was offered free of charge to consumers and by license to mobile network operators and handset manuf ...

plate girders, which use more material but have lower fabrication and maintenance costs. The term is also sometimes used to refer to a laced strut or laced tie, structural members commonly made using a combination of structural sections connected with diagonal lacing. This form allows a

strut A strut is a structural component commonly found in engineering, aeronautics, architecture and anatomy. Struts generally work by resisting longitudinal compression, but they may also serve in tension. Human anatomy Part of the functionality o ...

to resist axial

compression Compression may refer to: Physical science *Compression (physics), size reduction due to forces *Compression member, a structural element such as a column *Compressibility, susceptibility to compression *Gas compression *Compression ratio, of a c ...

and a (

tie Tie has two principal meanings: * Tie (draw), a finish to a competition with identical results, particularly sports * Necktie, a long piece of cloth worn around the neck or shoulders Tie or TIE may also refer to: Engineering and technology * Ti ...

) to resist axial tension. A lattice girder, like any girder, primarily resists

bending In applied mechanics, bending (also known as flexure) characterizes the behavior of a slender structural element subjected to an external load applied perpendicularly to a longitudinal axis of the element. The structural element is assumed to ...

. The component sections may typically include metal beams, channel and angle sections, with the lacing elements either metal plate strips, or angle sections. The lacing elements are typically attached using either hot rivets or threaded locator bolts. As with lattice girders, laced struts and ties have generally been supplanted by hollow box sections, which are more economic to produce with modern technology. In some case

seismic retrofit Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. With better understanding of seismic demand on structures and with our recent e ...

modifications replace riveted lacing with plates bolted in place.

Examples of lattice girders

Manhattan Bridge The Manhattan Bridge is a suspension bridge that crosses the East River in New York City, connecting Lower Manhattan at Canal Street with Downtown Brooklyn at the Flatbush Avenue Extension. The main span is long, with the suspension cables ...

Runcorn Railway Bridge The Runcorn Railway Bridge, Ethelfleda Bridge or Britannia Bridge crosses the River Mersey at Runcorn Gap between Runcorn and Widnes in Cheshire, England. It is alongside the Silver Jubilee Bridge. The bridge is recorded in the National Her ...

Kew Railway Bridge Kew Railway Bridge spans the River Thames in London, England, between Kew and Strand-on-the-Green, Chiswick. The bridge was opened in 1869. History The bridge, which was given Grade II listed structure protection in 1983, was designed by ...

Dowery Dell Dowery Dell, between Rubery and Halesowen in Worcestershire, was a , nine span lattice steel, single-track railway viaduct that carried the Halesowen to Longbridge railway. A 10 mph speed limit was in operation. The line opened in 1883. Trai ...

Viaduct *

Bennerley Viaduct The Bennerley Viaduct is a disused railway viaduct spanning the Erewash Valley between Awsworth (Nottinghamshire) and Ilkeston (Derbyshire) in central England. It was built in 1877 but closed to rail traffic in 1968, as part of the Beeching cu ...

Cayey Bridge The Cayey Bridge, also known as Puente de Cayey, is an iron lateral lattice girder bridge in Puerto Rico that was built in 1891. It brings Puerto Rico Highway 15 over the Guamaní River. It is an extremely rare example of such a bridge in the ...

Dalguise Viaduct The Dalguise Viaduct is a lattice girder viaduct in Dalguise, Perth and Kinross, Scotland.Dalguise, Tay ...

Viaduc d'Ormaiztegi The Viaduc d'Ormaiztegi or Ormaiztegi Viaduct is a lattice girder viaduct in Ormaiztegi, Spain that was formerly used by a railroad to link a line from Madrid to Irun. It is now considered a historical monument. History The viaduct was designed ...

Examples of laced struts or ties

*The

Eiffel Tower The Eiffel Tower ( ; french: links=yes, tour Eiffel ) is a wrought-iron lattice tower on the Champ de Mars in Paris, France. It is named after the engineer Gustave Eiffel, whose company designed and built the tower. Locally nickname ...

. *The obsolescent eastern span of the

San Francisco–Oakland Bay Bridge The San Francisco–Oakland Bay Bridge, known locally as the Bay Bridge, is a complex of bridges spanning San Francisco Bay in California. As part of Interstate 80 and the direct road between San Francisco and Oakland, it carries about 260,000 ve ...

. The western span has been retrofitted with bolted plates replacing the lacing for added strength. The eastern span has been replaced. *The internal structure of the Statue of Liberty. *The sides of the

Cape Fear Memorial Bridge The Cape Fear Memorial Bridge is a steel vertical-lift bridge in North Carolina, USA. It carries US 17/ US 76/ US 421 across the Cape Fear River between Brunswick County and New Hanover County. It also carried U.S. Route 74 until ...

. *Certain viaducts of the Chicago "L" system.

References

{{Reflist Girders Trusses Girder

Overview

Examples of lattice girders

Examples of laced struts or ties

See also

References