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What are Joist?
Repetitive Members.
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What are Steel Joists?
Steel beams that replace 2x4 w/ C-Sections (C-Joists, or light-gauge joists)
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What is a Gauge
- The thickness of steel (G.A.)
- The smaller the number, the thicker the steel.
- - floor systems, they are thicker steel
- - thickness will always be 1-1/2" wide
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How to use steel joists in flooring.
- Bolt or rivet together.
- Need to double or triple up to create stairway (a cut in the middle we must box it out.
- Subfloor can still be plywood
- - common w/ wood flr const.
- 4' O.C. or 5' O.C.
- - can span greater distances
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What are Open Web Steel Joists (Bar Joists)? 4.19
- Very light weight, can span very long distances (60') but are very tall
- To connect to foundation system, they need a bar joist seat (4.20)
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What are Metal Decks? 4.22
- They are corrugated
- Strong in axio direction
- We want ribs to run perpendicular of bar joists
- Pour concrete on top
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What are Metal Form Deck?
It's a form for the concrete
- Wire welded mesh
- We end up w/ a roughly 3.5-4" concrete slab
- Once concrete is cured, the deck doesn't do much.
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Why in Metal Form Decks, when concrete is cure, the deck doesn't do much?
- Concrete in drying process actually contracts, it looses a lot of it's water.
- Spawling (concrete chips away)
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What are Metal Composite Decks?
- Stud Welds (weld-studs) are used
- - when pouring concrete, it goes around wel-studs and the deck and concrete become one.
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What are Metal Cellular Decks?
Take form deck and putting sheet metal at the botton to run communication lines.
We don't really see this anymore.
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What are different sizes of Steel Beams?
- S-Section
- W-Section
- C-Section
- Angle Iron
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What are S-Sections?
- Steel Beams
- more light weight
- more residential
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What are W-Sections?
- Wide Flange Beams / steel beams
- Flange wider than the S-Section
- Much Stronger.
- W 10X32
- - W= Wide Flange
- - First number = height of the member
- - Second number = weight/foot (lbs)
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What are C-Sections?
Steel Beam that look like a C
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What is an Angle Iron?
- Most common lintel to bridge across a window opening
- Equal and Unequal
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What are the 2 types of categories in Concrete Floor Construction?
- Pre-Cast Concrete Floor Systems
- Pour in Place (Cast in Plate) Concrete
- Pre-Stressing Concrete
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What are Pre-Cast Concrete Floor Systems?
- Created at a factory in sections and trucked to the site and lifted by planks.
- In conventional system, it would be used as flooring.
- Width of the rooms and corridors are the same, good for motels, dorms, etc.
Hollow Core Pre-Cast Planks
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What are Hollow Core Pre-Cast Planks?
The cores are used for electrical and small plumbing.
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What are Pour in Place (Cast in Place) Concrete 4.05,4.06,4.07
Hard to conceal mechanical or electrical concrete
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What is Pre-Stressing Concrete?
- Positive Camber
- 2 Methods trying
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What is Positive Camber?
If we create a positive camber on a pre-loaded floor, we anticipate the floor and when loading the floor will flatten. If it's not positive camber and we apply load, it will deflect sooner.
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What is Pre-Tensioning?
- Take steel before concrete is poured and put a tension on it (rubber band and stretching)
- Hold steel in stretch position
- Pour concrete and let cure
- Cut off the steel, it will rebound then, spring back a lil' (1/4-3/8")
- STRETCH STEEL PRE CONCRETE
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What is Post-Tensioning?
- You pour the concrete
- Let concrete to cure to a point, not fully
- Then around 75% we then stretch the steel
- Let concrete to cure, cut ends of steel and it springs back.
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