What are Joist?
What are Steel Joists?
Steel beams that replace 2x4 w/ C-Sections (C-Joists, or light-gauge joists)
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
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
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)
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
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.
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)
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.
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.
What are different sizes of Steel Beams?
- Angle Iron
What are S-Sections?
- Steel Beams
- more light weight
- more residential
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)
What are C-Sections?
Steel Beam that look like a C
What is an Angle Iron?
- Most common lintel to bridge across a window opening
- Equal and Unequal
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
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
What are Hollow Core Pre-Cast Planks?
The cores are used for electrical and small plumbing.
What are Pour in Place (Cast in Place) Concrete 4.05,4.06,4.07
Hard to conceal mechanical or electrical concrete
What is Pre-Stressing Concrete?
- Positive Camber
- 2 Methods trying
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.
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
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.