Structural Engineering SciTech 11

What is a structure? ______________ – something that is ___________________ Joining parts to meet a certain _______ or perform a _______________

Types of Structures Natural Structures

Types of Structures Human Structures http://www.smh.com.au/articles/2007/11/17/1194767025118.html

Design Design depends on ______ -dam must be ___________ -tower to transmit tv and phone signals must be __________ -houses built for ___________ and _____________ -factories and offices for ______________

Who Designs Structures? Civil Engineers – ______________________ _____________________________________ -most work on roads, water systems, sewers, and public structures Structural Engineers – civil engineers that focus on _____________________ Architect – ______________________ and oversees construction

Who Designs Structures? Questions they might ask: -how many __________ or ____________ on bridge per day -how might skyscraper be affected by ____________________ -how to protect a structure in ____________________

Forces on Structures Force – __________________________ ______________ to an object External force – come from __________, act _____________ the structure Internal force – force that ____________ _____________, act _________ structure

Types of Forces 4 types: compression, tension, torsion, shear 1. _____________ – shortens or crushes 2. __________ – stretches or pulls apart 3. ____________ – twists 4. ___________ – pushes parts in opposite directions

2.3 Internal Forces Within Structures Compression, Tension, and Shear Compression forces crush a material by squeezing it together. Compressive strength measures the largest compression force the material can withstand before it loses its shape or fails. Tension forces stretch a material by pulling its ends apart Tensile strength measures the largest tension force the material can withstand before failing. Shear forces bend or tear a material by pressing different parts in opposite directions at the same time. Shear strength measures the largest shear force the material can withstand before it rips apart. Torsion forces twist a material by turning the ends in opposite directions. Torsion strength measures the largest torsion force the material can withstand and still spring back into its original shape.

Types of Forces Load – _________________ acting on an object, eg: ___________, pressure from wind/water Static Load – _____________________, eg: bricks in a building, twigs in nest Dynamic Load – __________________, eg: car crossing bridge, oil in pipeline

Structural Materials Wood -one of the ______________ used for structures -still the ________________ materials for _________ production -comes in many varieties -for construction, strong wood used = ________ __________ -________ of wood helps determine _________ (size, shape, direction of fibres)

Structural Materials Disadvantages of wood: -_______________________ with changes in ________________ -damaged by _______________________ -breaks down if not maintained

Engineered Wood -_______________ wood strands, fibres, veneers with _____________ -can __________________________ -formed into panels, laminated beams, I-joists -structural panels (___________) most common -made by gluing together ____________ -odd number of layers, _________________ -less likely to ________________________ (_______________________)

Structural Materials ________ -laminated, used for ________ construction in homes -light, available up to 60 ft, don’t ______ or _________ -eliminate ________________ because don’t shrink

Structural Materials _____________________ -glue together ______________ of wood -consistently ____________, can be made very long

Steel Steel is an ________ (metal made of _____________________) made from ________ and _________ may have _____________ and ________ to _____________ made into _________________ (I-beams, pipes, wires) and joined many ways (rivet, bolt, weld) used as _______ or ________ to strengthen _____________

Concrete made by mixing ____________________ ________________________ hardens into strong material examples? very _________ in _______________ poured into forms to make almost ______ ______________

Concrete _______________ -may be reinforced with steel bars to make ____________________ _____________ concrete contains ______ that are under __________ all the time produce beams, floors or bridges with a _____________ than reinforced concrete wires produce a ___________________ that offsets ___________ stresses

Structural Members Structural Members: -building materials joined to make a __________________ Common shapes include:

Bridges Before a bridge is built: -_______ samples -_______ speed and direction -_________ levels and speed of water -models tested in lab or on computer -community hearings -planning takes several _________ and _____________ of dollars!

Bridge Types

Skyscrapers History: -___________________ in ancient Egypt, which was 146 metres (480 ft) tall and was built in the 26th century BC -Ancient __________ housing structures reached 10 stories -Medieval times: many towers built for ______________ -_______________________ built in 1178

Skyscrapers -first “skyscraper” was Home Insurance Building in _____________, 1885 -____ stories -load-bearing ____________ instead of load-bearing walls -practical with the invention of the ______________ (no more stairs!)

Skyscrapers -Current record = ___________ @ ______ __________, 1,670 ft tall -has huge ______________ near top to counteract ______________ http://en.wikipedia.org/wiki/Taipei_101 http://en.wikipedia.org/wiki/Taipei_101

Skyscrapers -high quality ________________ bear immense weight -beams _________, _________, or _________ together -most weight is transferred to _________ _____________, the spreads out at base and substructure -_______________ is a major concern

Wind Resistance -many tall buildings __________________ in strong wind -structure is _____________ constructed to _______ movement -_____________ monitor sway and move huge _________________ to compensate http://www.youtube.com/watch?v=j-zczJXSxnw http://www.youtube.com/watch?v=j-zczJXSxnw http://www.youtube.com/watch?v=j5j20NSFNcg

Earthquake Resistance -ban construction along ______________ -many buildings built on layers of _______ ___________ or a ____________ surface http://www.youtube.com/watch?v=4Y-62Ti5_6s http://www.youtube.com/watch?v=kzVvd4Dk6sw http://www.teara.govt.nz/EarthSeaAndSky/NaturalHazardsAndDisasters/Earthquakes/4/ENZ-Resources/Standard/4/en