Advice for a steel frame construction [pole house on slope]

KateG · Oct 28, 2017 8:12 am

Hi,

we’re going to build our first home as owner builders. The house is completely designed by now. The only thing we’re struggling with is the stilt construction the house has to sit on.

As we’re building on a slope we need a proper steel frame as construction to lift the house out of the ground. The architect came up with an idea but we’re not sure what to do now.

What is the best and most cost efficient way to go on?

Going to a technical engineer to do all the math? (Maybe someone has an idea what this will approximately cost)
Finding a steel frame construction company that will erect the frame in the end and ask them to check integrity?

Or is there any better solution? Any idea is very welcome.

Have nice weekend.

KateG

StructuralBIMGuy · Oct 28, 2017 8:56 am

KateG

The architect came up with an idea but we’re not sure what to do now.
What is the best and most cost efficient way to go on?

Going to a technical engineer to do all the math? (Maybe someone has an idea what this will approximately cost)
Finding a steel frame construction company that will erect the frame in the end and ask them to check integrity?

Or is there any better solution? Any idea is very welcome.

On difficult builds always start with a Design Engineer, Data and Proofs
Architects and designers come up with many ideas but most wouldn't have a clue about optimization and cost benefit analysis in using one type of frame system over another unless they actually engineer and build.
BTW, You will need to put up more information,ie, Size Build, Budget, BAL, Terrain accessibility,Single/split/double storey, Foundation type, Buildability,etc,etc,
Why don't you look into importing prefab steel frames from China?

KateG · Oct 28, 2017 1:31 pm

Thank you for your answer StructuralBIMGuy,that might be the case here. I would rather ask someone, who actually builds these kind of structures and can engineer and build ours as well. I’m happy to share project details and hope that helps to get me some advice.

Building site is on a 25% slope, Type A soil, wind rating N4. Foundation are either concrete footings or maybe those Sure-Footings, that work like tree roots to hold the building down on a windy day.

To import a frame from China sounds good to me and I’m open to every good solution. Would you recommend a company over there? If a Chinese company designs and engineers the frame we have to have an engineer in Australia to sign for it, right?

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StructuralBIMGuy · Oct 28, 2017 6:09 pm

KateG
If you Architect has the 3D Bim Model they can send it to a structural engineer (in RVT or IFC format) to analyse the frame sections with 50m/s (150 kph) wind gust loads
The model will need to be tidied up at a Glance (Compared to very large Billboard) & Quick calc I have those SHS columns failing..UC maybe ?
Then you will need to get all the steelwork connections detailed here, email fabrication Drawings & Details, and they can price up the tonnage plus shipping. BTW you still require a lot more work/details on those drawings. Can you get Crane & Pump access to your block?

manofaus · Oct 28, 2017 7:28 pm

check out duragal flooring system. they have a design guide or technical guide for such things. 90 x 90 x 2mm is good for 4.5m. The cheaper you want to go the more bracing you will need at that height.

Carpentacular · Oct 29, 2017 7:49 am

That's a nightmare so many post seeing it's on such a slope, I'd be getting someone else to design a better subfloor that won't be so difficult.
I'd build two pier and beam arches one half span of course something like in this link and a slab to suit it.
pier and beam arches

The set up on all those posts on such a slope is a difficulty builtin from the start, find an architect who has actually done work on houses and you'll win every time.

StructuralBIMGuy · Oct 29, 2017 9:09 am

manofaus

check out duragal flooring system. they have a design guide or technical guide for such things. 90 x 90 x 2mm is good for 4.5m. The cheaper you want to go the more bracing you will need at that height.

Where does it specifically say that on their technical brochure?
Duragal flooring system
KateG That's the problem LOL... looks great as a rendered Image but in reality it's technically worthless if it can't be build that way within your budget.
OT On difficult builds you should have it roughly designed in sketchup, then have the Structural Engineer do preliminary analysis & estimates for size and tonnage. Instead of Going straight to planning and then having to redesign it for whatever reason.

Beetaloo · Oct 29, 2017 11:35 am

The drawing shows posts at 2400mm centres. That means a lot of posts. I would have the posts a lot further apart with larger beams
(I live in a stilt house built on a very steep block).

Is your land in high BAL area? If it is, special measures may be required to prevent embers blowing in under the house.

KateG · Oct 29, 2017 3:48 pm

Hi Beetaloo, no it is not in a BAL area, we have a 12,5. How big are your poles and how far is the distance between them?
Best regards Kate

manofaus · Oct 29, 2017 10:22 pm

You need the duragal version 7 matey. You are looking at version 6.
https://www.onesteelmetalcentre.com/~/m ... ochure.pdf

manofaus · Oct 29, 2017 10:27 pm

If you considered alternatives to steel, you can use LVL's (use designit software). I have 3.3 cts for LVL bearers and using I joists which are spanning 4.0m (450 cts)

StructuralBIMGuy · Oct 29, 2017 10:58 pm

manofaus
Here's the index link for duragalv Building Products flooring System spans for joist/beams only
None of those brochures refer to Column support heights & engineering section property ...where specifically does it say 4.60m high
because that's what KateG is asking for?

"KateG
How big are your poles and how far is the distance between them?
Best regards Kate" Quote

KateG · Oct 30, 2017 1:08 pm

Yes that's it thank you.

StructuralBIMGuy · Oct 31, 2017 9:16 am

KateG
In the words of Chris Rock, "There's math and everything else is debatable"
The same is said of Architectural/Artistic Rendering without data and proofs
When you compare the various Steel Columns/Floor systems ie, Rolled sections (RSJ), Cold formed sections (CFS) things to consider,ie Site accessibility, material handling, Fixings,Engineering, Owner builder skill set, ease of fabrication, etc,etc
BTW material costs for patented building systems are up to $10K/ tonne, RSJ $1k/Tonne and CFS $5k/Tonne
Get the 3 options drawn/engineered/analyzed, work out the tonnage and do the math... you will see a clear winner
OT i do admit the duragalv brochure does look impressive to owner builders...but you can get the same 3D details and instructions of your customised plans from my structural BIM software with data and proofs
Make sure your Structural Engineer gives you the 3D BIM Model
If you are starting from scratch get the whole Archi/Design, Engineering & Construction (AEC) in 3D BIM by someone who competent in all disciplines and avoid $ticker $hock. HTH
Cheers

KateG · Oct 31, 2017 7:37 pm

Thank you so much for your advice. It helped a lot. To sad that you are in WA and we in NSW.
All the best for you! KateG

StructuralBIMGuy · Oct 31, 2017 9:11 pm

KateG you are welcome..BTW if onsite material handling is going to be a problem then
you might consider asking your Engineer about floor span truss design
The fabrication costs of Light weight Trusses from China are low..HTH
Please keep the forum updated..Thanks