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Engineering
Science
term/ question | answer/ definition |
---|---|
Three main kinds of bridges | beam, arch, suspension |
span | length of the whole bridge from end to end |
truss | a framework of beams arranged in Xs or triangles |
piers | vertical supports that hold up bridge made up of prestressed concrete or steel |
abutments | the land on both ends of the bridge |
bridge deck | roadway or walkway part of the bridge |
reebar | thin steel rods used to strengthen prestressed concrete |
I beam | steel beam used to build large structures |
cantilever bridge | a beam bridge with special structures projecting from piers |
caisson | special box used to keep water out while digging piers |
cable- stayed | special kind of suspension bridge with cables connected directly to bridge deck at an angle |
goals of an engineer for designing a bridge | Safe, strong, visually appealing, economical, long lasting |
what does safe mean in the goals of an engineer while designing a bridge | safe: look at what could possibly happen that wouldn't keep the traffic moving safely and plan/build for it |
what does strong mean in the goals of an engineer while designing a bridge | using the correct size and strength of materials for amount of traffic and future traffic |
what does long lasting mean in the goals of an engineer while designing a bridge | get the most years by good planning and long lasting materials |
what does economical mean in the goals of an engineer while designing a bridge | stay on budget, don't spend more money than need for this bridge in this place |
what does visually appealing mean in the goals of an engineer while designing a bridge | make it look good, think about if it is a place that could become a tourist attraction |
two reasons bridges fail | weather; wind and storms too strong for the designs and building mistakes/bad job by workers during construction |
two other reasons bridges fail | incorrect strength or quality of materials used during construction natural disasters; unforeseen events such as earthquakes or floods |
what kinds of models are by engineers/architects before building structures | 2 dimensional models- blue prints or drawings 3 dimensional models are built in miniature version |
2 things engineers and architects must consider about a specific bridge type | - how long the bridge will need to be to reach the abutments - what the bridge will be used for or traffic it will need to carry |
2 other things engineers and architects must consider about a specific bridge type | - how strong the riverbed earth is - the currents and tides in the area |
two modern materials used most today | prestressed concrete and steel |