Bridge test

What are 8 key questions to consider when designing and building a bridge? (p. 8)

1. What is the span of the bridge? 2. What will be the load on the bridge? 3. What type of load will the bridge have? 4. What environmental factors will affect the bridge? 5. What is the budget allowance for the bridge? How much will it cost? 6. What are the soil characteristics of the banks where the abutments will be? 7. What are the soil characteristics at the bottom of a body of water if support columns are needed? 8. What is the time frame in which the bridge must be built?

What is a bridge?

A bridge is a structure designed to permit pedestrians and vehicles to cross over some obstacle (rivers, bays, or other bodies of water, deep gorges, another road, railroad yard, etc.)

Explain the importance of using a triangle in bridge design

A triangle is a very strong geometric shape (stronger than a four-sided shape) and difficult to change. The triangle is able to distribute forces equally over the entire shape so that the load is not concentrated on one member.

Compare and contrast tension and compression

Both are forces acting on the structure of a bridge. Tension is a pulling force and is active in the cables of a suspension bridge. Compression is a pushing or squashing force and is active in the stones of a stone arch bridge (or the concrete towers of a suspension bridge)

Name several of the most important suspension bridges and where they are located

Brooklyn Bridge - New York City Golden Gate Bridge - San Francisco Akashi-Kaikyo Bridge - Japan

What is civil engineering/ what do they do

Civil engineering is a profession dedicated to the construction of roads, dams, communication towers, etc. (p. 7)

3 earliest bridge types

Pier & beam: fallen logs or clapper bridge — Tarr Steps; Suspension bridge: woven grass fiber rope bridges of the Inca Indians; Stone arch bridge: Romans

What is racking and how can racking be fixed? (p. 9) Draw a diagram to help explain the idea of racking.

Racking is the kind of stress that distorts a square. Add a diagonal from corner to corner to prevent racking.

What people were responsible for building the ancient stone arch bridges?

Romans

What kinds of stresses occur in the cables of a suspension bridge.

Tension

What happens to a deck when the deck's upper surface is compressed and its lower surface is under tension? (see Fig. 3 p.8)

The deck will bend

List the factors that led to the halting of bridge building during the dark ages. (p. 1)

The economic and social breakdown of the period led to the stoppage of bridge construction.

Where did most bridge trusses get their names?

The ppl who designed and built them

What are the advantages of using wood for bridge building? (p. 5)

Wood is readily available, cheap, renewable, and strong. Its greatest disadvantage is that it rots over time and when left untreated, is also subject to insect damage.

T-beam(t-brace)

a T-shaped support added to the end posts, top chord, etc. to strengthen a wood splint bridge

Gusset plate

a plate used to reinforce a joint

Truss

a structural framework made up of straight members arranged into triangles

Strut

a support holding the left and right sides of a bridge together

Floor beam

cross member beneath the road that helps to support the road

Span

length of the bridge from one end support to the other

bridge efficiency

mass of load ÷ mass of bridge be able to calculate the efficiency

Steel cables

suspension bridge structures which hold up the deck

Substructure

the part of the bridge below the road

Deck (or roadway)

the structure on which vehicles travel

Superstructure

the truss above the deck or road

Load (live and dead)

the weight supported by the bridge; live load is the weight of the traffic expected on the bridge; dead load is the weight of the bridge itself.

Bottom chord

very top horizontal beam of a bridge truss

Top chord

very top horizontal beam of a bridge truss