G4 - Slabs LT #2 - Slab-on grade & Suspended Flashcards
What is the difference between a flat plate slab and a flat slab?
1) Flat plate has a plain soffit
2) Flat slab will have a drop panel or column capital
What advantage do column capital give?
Increase shear strength and reduce span
What direction does load-carrying steel span?
Perpendicular to the beams
Dome pans are used in which type of slab?
Two way
How does a two-way joist system differ from a single-joist system?
Two-way joists run in 2 directions, One way joists run in one direction
In what sequence does form stripping usually take?
Beam sides first then the slab soffit
How are wooden T-shores set to elevation?
Wedged
How are forms for drop panels supported?
Shores, stringers and joists
What is the slenderness ratio?
1:50 MIN thickness of post:Unsupported height
Describe three ways single shorers are made adjustable
1) Screw jacks
2) Wood wedges
3) Ellis clamp
Why are re-shores not fitted tightly to the concrete that they are supporting?
To not place undue pressure on the concrete while reshoring
Describe a slab table
Truss shoring, stringers, joists, plywood deck and screw jacks
What are flying forms?
Fly tables or gang forms LIFTED by crane
How are Aluma-beams attached to the falsework?
Slotted bottom and bolt
What is a mudsill used for?
Distribute the weight
Using a slenderness ratio of 1:50, what is the maximum unsupported height of a rough 4x4?
(4 X 50 ) / 12 = 16’8
Flat plate slab relies on what for it’s own strength?
It free spans to support and relies on its own strength and rebar, won’t span very far.
What is a flat slab?
Similar to flat plate
1) Columns hold slab up, either a column capital or drop panel or both
What is a column capital?
Column capital and drop panels add extra concrete at the shear areas above the columns, reducing the unsupported span of the slab
What is a column capital?
Column capital and drop panels add extra concrete at the shear areas above the columns, reducing the unsupported span of the slab
What is a one-way slab?
Support running from column to column one way
What is a two-way slab?
Steel runs in both directions
Describe a one-way ribbed slab.
Series of metal pans secured end to end to the slab deck to create a joist pattern in slab
In a ribbed slab, the pour is:
Monolithic and thin, reducing some of the dead loads of the building.
What does a slab band do?
Similar job to the drop panel, except they span continuously from column to column, in one direction only.
The beam at the perimeter of a suspended slab is called what?
A spandrel beam
How are capital forms designed?
To attach to the column’s formwork at the top. Very economical as they can be used again and again. Pre-fab metal and fiberglass mold.
What is a drop panel?
Basically square in shape and flat on the bottom, easier to form out of plywood
The underside of the slab is known as
Soffit
Plywood is known as
decking
Shoring is referred to as
Falsework
Falsework supports what
The formwork for the concrete structure
What does falsework require?
1) Foundation
2) Vert/Horizontal structural components
3) Horizontal bracing in both direction and diagonal bracing
Falsework can be built from wood using
4x4, etc, with 1x6 for bracing
Today most shoring is:
Steel or aluminum, metal is stronger and prefab makes easy and quick set up
What is the slenderness ratio?
Not exceed 1:50, where 1 is proportional to the minimum cross-sectional dimension and 50 is the unsupported height of the shore
What are the two common fly forms?
Gang forms used for forming walls and slab tables used for suspended slabs
