Tech bridges test

dynda 9.28.26

bridges

because our ancestors were wanderers, there first production projects were probably _______________

tensile

Forces that try to tear something apart are called ________ stress

compression

Forces that squeeze things together are known as _______ stress

shear

When two materials try to slide by each other causing the material to tear, the stress is known as _________ stress

torsion

When materials twist and bend, the forces are called _________ stress

Galloping Gertie

A bridge that blew down in Tacoma, Washington moved around so badly that before it blew down it was called __________ _____________

compression, tension

When a heavy load is put on a bridge, the material on top _____________ while those on the bottom are acted on by _______________ forces

twisting

When a bridge twists due to wind or uneven loads, ________ forces act on the bridge materials

steel, concrete

In modern bridges the two most often used materials are __________ and ___________

girders

Steel bridge parts are often in the shape of box or an "I". These shapes are called ___________

sand, stone, cement

Concrete is a mixture of ______, _______, _______, and water

compression, tension

Concrete has good __________ properties, but is poor in ___________

steel rod

Thaddeus Hyatt discovered that a _______ _____ put near the bottom of a concrete beam would give more support for the beam

pre - stressed

When rods, wires, or cables are put inside a drying concrete beam and tightened before the concrete dries, the result is known as _____ - _________ concrete

girder

When steel beams are laid between two piers or supports, the bridge is known as a __________ beam bridge

cantilever

When a beam bridge supports a middle beam the bridge is known as a ______________ beam bridge

truss

When a beam bridges uses a series of triangular shapes to support a beam, the bridge is known as a ____________ beam bridge

arch

When the Romans built aqueducts some of them had bridges going through them, they were usually ________ bridges made from stone

Abutments

Part of a bridge that rests on the ground is called an ________

keystone

Stone used in the top of a stone arch bridge is known as a ________

suspension, long

Bridges that hold the road surface by cables are known as __________ bridges and are usually used over __________ distances

cable - stayed

A bridge that suspends the road surface from only one tower is called a ________ - __________ bridge

cassion, bedrock, pressurized

When bridge piers need to be built underwater, a heavy, reinforced ___________ is lowered into the water. Its wait forces it down towards ___________ where it will remain filled with concrete as the bridge pier. A __________ work chamber allows workers to dig through the sand and keep water from entering

coffer dam

When building piers in shallow rivers, where bedrock is close to the surface, a cassion with an open top and no pressurized work area can be used. This device is called a ________ _____

Terrain, reason, length of span, and weather

When designing a bridge 4 things must be considered: ________, _________, _______ __ _______, and _________

wood, stone, metal, concrete, composite

Bridge construction materials

wood

used in early beam

stone

used to make arches

metal

used to make beam & suspension

concrete

used with metal in modern beam

composite

newest construction in all

tension bridges

Cable-Stayed, Suspension

Arch bridges

Through Arch, Deck Arch, Half - Through Arch

Beam bridges

Girder, Truss, Cantilever

Types of bridges

Beam, Truss, Arch, Suspension

buckling

Heavy compressive load that causes spontaneous and extreme bending and, inevitably structual failure.

Bending

a combination of tension and compression in a single element and, inevitably structural failure. (bottom is tension top is compression)

shear

cutting

torsion

twisting

compression

pushing

tension

pulling

Dynamic load (live load)

Like the strike of a hammer, Causes the structure to move

Static load (dead load)

Static load (dead load)

Gravity

Buildings and their contents have weight, Foundations must support all things

Wind

Sideways pressure

Earthquakes

In some locations like California

Gravity

The force of gravity on an object is large if the body that pulls on it is large, like the earth. If the body that pulls on it is only one-sixth as large as the earth, like the moon, the pull is six times smaller.