Find number of formwork steel H frames that are required for an area

[zillah]

Dear Experts

I couldn't find an answer when I searched google

My friend is a form-worker and he asked me how can we find roughly number of H frames (link below showing dimensions as well)
) that are required for an area ?

https://www.scafeast.com/product/1-8m-h-frame/

https://www.victoriascaffolding.com....uct/frame-set/

distance between one frame and other is approximate 1.5 m

Those frames would be used to support plywood sheets for a slab before pouring concrete similar to the below link

https://www.shutterstock.com/image-p...pfxWBgPvA-1-14

Thx

[AlexS]

You need to ask a structural (Civil) engineer. Designing something like this is not a job for amateurs.

[Beardy]

You don’t need an engineer but if your mate is a formworker he wouldn’t need to ask such a question
The set out of your shoring frames or props will be dictated by the structural form work timber sizes you intend to use and the shape of the area you intend to form up.
Maybe you need someone with more experience for your intended project? A mistake apart from being dangerous will be very costly to rectify

[zillah]

Thx Beardy

he is a form worker and I asked couple of other form workers as well they couldn't figure it out

I will post the question in structural engineer forum and I will see if they have a way to find out

Any way thanks for trying to help

[ian]

There is a reason why you should involve a structural (or formwork) engineer.
When the frames and beams supporting a concrete pour collapse, someone usually ends up DEAD or badly injured. And the person responsible for the formwork "design" spends the following few years battling to stay out of jail.

[zillah]

You are right
Design is approved and distances 1.5 m between frames are approved by structural engineer
There is no risk and OHS issue at all

[ian]

based on your links, each frame set (two H frames and bracing) is 1.2 m wide and 1.5 m long.
each frame can support two beams (or bearers) in either the longitudinal or transverse direction.
Given that one way the supported span is 1.5 m, and the other way it's 1.2 m, what does the design specify?

working out the number of frames should be straight forward maths.

[zillah]

Thx
If area say 650 m2
Bearers or beams run in the direction of 1.2 m
How can i find numbers required ?

[rustynail]

Use the area dimensions and divide by frame centre measurements, will be close enough for quantities.

[rwbuild]

A lot of the specialist formwork hire companies will work it out for you if you give them a plan and the slab engineering details

[ian]

You are right
Design is approved and distances 1.5 m between frames are approved by structural engineer
There is no risk and OHS issue at all

the supports still need to be put together properly, leveled and supported on a base that won't sag (or compress) once loaded with a slab's worth of wet concrete.

[zillah]

Use the area dimensions and divide by frame centre measurements, will be close enough for quantities.

Thx rustynail I guess it might very close , I will try to check it

Credit goes to cyclic from renovate forum

Fairly simple math really.
If a frame is 1.8 meters and has a gap to the next frame of 1.5 meters, then a frame covers 3.3 meters, so, length of deck in meters divided by 3.3 meters = number of frames +1 for the extremity..
Same for width of deck, then multiply the 2 answers.
eg deck is 30 meters x 22 meters.
30 divided by 3.3=9.09+1 for the extremity=10 frames covers 33 meters.
22 divided by 3.3=6.6+1 for the extremity = 7 frames covers 23.1 meters.
So 10 for length multiplied by 7 for width = 70 frames is a rough calculation.
Or am I missing something ???