G-3 Build Footing and Vertical Formwork Flashcards
Fottings
at the base of foundation walls there is a footing. they must be accurately placed and level to make rest of build easier.
Three types of simple footings
- trenched
- partially trenched
- fully formed
Footing latters
simple way to form footings. boards held together by cleats. assembled and then connected to form footprint of building.
Continuous strip footings
footings that support a foundation wall are usually continuous
Keyways
placing a beveled 2x4 blockout into the footing that is removed to leave a small channel.
Steel stakes
perfect if the ground is solid. keep forms from moving and can be used to set height of footing
Column Footings
footings for small columns are usually rectangular boxes made from 2” material and are pre build using wrap “around technique”
Tapered pier footings
pressure from concrete always pushes outwards on forms. these forms need to be weighted down to resist upward push
Bearing on soil Raft slab
The most common type of raft slab is used to spread the weight of the building somewhat evenly over the entire footprint
Bearing on piles
raft foundations can be set on piles instead of soil if drilling to them makes sense.
Floating foundations
Deep raft and concrete foundation walls displace enough soil by weight to equal the weight of the building placed on the foundation.
Mass slab foundation
Mass slab footing is a heavy block of concrete used to anchor down a tall building.
Pile Foundations
Are used when the soil bearing capacity is insufficient to carry the required loads. “deep foundations” are used that have piles or caissons going down deep to bedrock. can be driven in vertically or on and angle to protect against seismic or wind events
Caisson.
larges hollow concrete sections are driven with pile driving equipment
Bearing piles
consist of different materials such as wood and steel and concrete. these extend down to bedrock or other solid soils that can withstand and support structure.
Bearing piles transfer vertical loads down to solid ground.
Point of refusal
bedrock or soil that is able to withstand the loads placed upon by structure. this is a measurement of resistance against the pile driving equipment.
Pie swelll
displacement of soil by the pile being driven into ground
Pre fab forms (GANG forms)
these save time and money during construction. come in many forms and shapes.
Self climbing forms
use tie holes or tie hardware from previous concrete placement to anchor climbing shoes and support the forms and working decks. once concrete is set then it is transferred up to next level
Slip Forming
also known as “gliding formwork”, is a process where formwork moves continuously. uses very strong yokes to support wall forms. used for forming round or rectangular shapes.
ICF (insulated concrete forms)
Forms are left in pace to act as insulation.
Flat wall
a wall that has uniform concrete thickness over the height and width of the wall.
ICF concrete wall thickness is specified based on?
backfill height. and the amount of rebar used.
Plywood forming systems
standard 4x8 ply used
12” increments for holes is common
normally paper-faced produces a good look after form is stripped.
Wall form Corners
built and assembled first. usually required extra reinforcements (corner clamps). must be plum and level
Setting up panels
begins at the corners, once they are braced and plumb the rest of the full panels are installed. make sure they are tight together to prevent leakage
then whalers and ties/ bracing is installed to complete outside wall form.
Gang form construction
forms are lifted and moved by a crane and used again and again. these use fewer form ties and have heavier studs and walers.
ALuma beam system
works well for gang forms because they are very strong light and easy to connect together.
Moving two gang panels at once
this is a fast way of concrete corming where both sides of a form can be rigged up and moved at the same time. the use of a spreader bar so that the strings are straig
why must you have a spreader bar when moving gang forms.
so that the ropes fall vertically and do not pull the strong backs together.
Concrete strength
cast in place concrete members will not reach their fill strength until 28 days after the concrete is placed.
removal procedure of cast in place concrete
- cast in place concrete must not be subjected to loads for 28 days
- forms of walls must be left for 7 days
- forms for beam girders and soffets left for
14 days if less then 20 feet
bigger then 20 feet 21 days
slabs 28 days - time above are minimim
- remove forms carefully
- limit loads until this time has passed
Pre mature stripping can cause
can cause spalling: pulling out chunks of concrete
