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Bay Bridge Info

Glossary

Glossary

Abutment – The outermost end supports on a bridge, which carry the load from the deck

Anchorage – A secure fixing, usually made of reinforced concrete to which the cables are fastened

Beam – A rigid, usually horizontal, structural support element

Bedrock – The solid rock layer beneath sand or silt

Brace – A structural support; (v) to strengthen and stiffen a structure to resist loads

Cable – A structural element formed from steel wire bound in strands; the suspending element in a bridge

Caisson – A watertight, dry chamber in which people can work underwater

Cantilever – A projecting structure supported only at one end, like a shelf bracket or diving board

Catenary – The inverted arch shape that the main cables of a suspension bridge make by supporting the weight of the bridge’s deck

Cofferdam – A temporary dam built to divert a river around a construction site so the dam can be built on dry ground

Column – A vertical structural support element

Compression – A pressing force that squeezes a material together

Concrete – A mixture of water, sand, small stones and gray powder called cement

Deck – Supported roadway on a bridge

Deform – Change in shape

Force – Any action that tends to maintain or alter the position of a structure

Joint – A device connecting two or more adjacent parts of a structure; a roller joint allows adjacent parts to move controllably past one another; a rigid joint prevents adjacent parts from moving or rotating past one another

Load – Weight distribution throughout a structure; loads caused by wind, earthquakes and gravity affect how weight is distributed throughout a structure

Maximum Credible Earthquake – An earthquake of magnitude 8 on the Richter scale along the San Andreas Fault, or a magnitude 7.25 quake along the Hayward Fault

Pier – A vertical supporting structure, such as a pillar

Pile – A long, round pole of wood, concrete, or steel driven into the soil by pile drivers

Pile Driver – A noisy machine that repeatedly drops a heavy weight on top of a pile until the pile reaches solid soil or rock or cannot be pushed down any farther

Shear – A force that causes parts of a material to slide past one another in opposite directions

Span – The distance a bridge extends between two supports

Stable – Ability to resist collapse and deformation; stability characteristic of a structure that is able to carry a realistic load without collapsing or deforming significantly

Steel – An alloy of iron and carbon that is hard, strong, and malleable

Stiff – Ability to resist deformation

Strong – Ability to carry a realistic load; strength the measure of a structure’s ability to carry a realistic load

Suspension Bridge – A bridge in which the roadway deck is suspended from cables that pass over two towers; the cables are anchored at either end of the bridge

Tendon – A pre-stressed cable, strand or bar

Tension – A stretching force that pulls on material

Tower – The vertical structure in a suspension bridge or cable-stayed bridge from which cables are hung

Truss – A rigid frame composed of short, straight pieces joined to form a series of triangles or other stable shapes

Unstable – Characteristic of a structure that collapses or deforms under a realistic load

Superstructure – A section of a bridge that is supported from beneath