Steel Beam into Cavity Wall without pillar?

[geraint]

unfortunately your bolting method is unsound.....

Go on then I'll bite, I'm struggling to see any major problems with this, so what's the problem with it?

to use m16 mm bolts is impossible with a 102mm section.. or possible but not structually sound...

any SE would laugh...

 

[freddiemercurystwin]

Even the one who designed it and drew it I suppose!

 

[karlosmaximos]

Have you thought about building a section of the internal wall in 7n blocks?

I've done this before in an extansion where the steel beams were approx 9m wide and were welded together before being craned in.

The section was 3 blocks wide, with a conc padstone on top,the customer designed bridges for a living, so it was well within spec.

Just my two penneth worth and i prepare to be slated for my comments lol

 

[seasickstevie]

With 7N block, I presume he'd have to insulate internally.
Then he's lost his super-smooth flat finish.

Or am I wrong?

 

[RonnyRaygun]

to use m16 mm bolts is impossible with a 102mm section.. or possible but not structually sound...

any SE would laugh...

Can't believe I'm going to say this but Grrraint is right...
BS5950 says

6.2.2.4Minimum edge or end distance.
The distance from the centre of a bolt hole to the edge or end of any part should be not less than the value given in Table 29

Table 29 gives 1.25D for rolled edges, which is 20mm for an M16 bolt. You are only left with around 12mm if using an M16 in a 178x102 UB.
It seems that this is a hard and fast rule, although as the connection is a simple connnection and the bolts aren't doing any real work, M12s would be ample anyway.

 

[alittlerespect]

Hi

You need to consult a structural engineer and the worst part about this whole situation is that the Architect should have advised you of this requirement right at the start of the design process.

The real issue here is 'can the existing walls and foundations take the additional loading'?

Solutions are various and the Structural Engineer will be able to provide the best advice!

Regards

 

[freddiemercurystwin]

Well blow me down, the old duffer gets us on a technicality!!! I'd better ring the client and make sure his extension hasn't fallen down!

 

[Ossy]

I think the technicality is wrong though.

According to the steel designer's manual (2003) the minimum cross c/c for a 102 wide UB is 50mm based on M16 bolts. This leaves an edge distance of (102-50)/2=26mm which is more than adequate for that bolt size. The drawing gives 60mm c/c which leaves (102-60)/2=21mm. This is still within the 1.25xdia. that BS5950 requires for a rolled edge. If memory serves the 178x102 is actually 101.9 or 101.6mm wide but it doesn't make any significant difference.

This may be below the given edge distance for the full bearing capacity (Pbs) of the bolt (not got the code to hand) but even so, this isn't going to have any significant horizontal load so it isn't an issue.

 

[RonnyRaygun]

You're right, was thinking the dimension was taken from the edge of the hole... so yeah, you end up with an edge distance on the info given of 20.6mm.

Although looking more closely 1.25D refers to the diameter of the hole, so we still need 22.5mm.

I agree though that the connection is never going to see any significant horizontal load anyway.

 

[GeorgeWBush]

With 7N block, I presume he'd have to insulate internally.
Then he's lost his super-smooth flat finish.

Or am I wrong?

What about insulate externally?

You need to consult a structural engineer and the worst part about this whole situation is that the Architect should have advised you of this requirement right at the start of the design process.

Down to bad communication really. The vision I had did not match what the architect had in mind. Architect made it clear on the plans there would be pillars - my own fault really for not taking this up with him.

 

[geraint]

You're right, was thinking the dimension was taken from the edge of the hole... so yeah, you end up with an edge distance on the info given of 20.6mm.

Although looking more closely 1.25D refers to the diameter of the hole, so we still need 22.5mm.

I agree though that the connection is never going to see any significant horizontal load anyway.

so why state m16. surely m12...

but again people using generic sketches....

easy money....

or pure laziness

 

[GeorgeWBush]

Our structural engineer has come back with some detail. Would really appreciate feedback on the following proposed approach:

View media item 31541View media item 31542
In summary, she has proposed the main beam would be a 254x254x89 UKC (Grade 275jr hot finished) fixed to 600mmx100mmx300mm pad stones with G8.8 M10 cast in rag bolts.

This single beam will be supporting the new back wall of our house, the upstairs new floor area, the roof above it and the new monopitch roof over the downstairs extension (please see link at the beginning of the post).

 

[geraint]

Our structural engineer has come back with some detail. Would really appreciate feedback on the following proposed approach:

View media item 31541View media item 31542
In summary, she has proposed the main beam would be a 254x254x89 UKC (Grade 275jr hot finished) fixed to 600mmx100mmx300mm pad stones with G8.8 M10 cast in rag bolts.

This single beam will be supporting the new back wall of our house, the upstairs new floor area, the roof above it and the new monopitch roof over the downstairs extension (please see link at the beginning of the post).

the grade and hot finished is nonsense...

and what the cast in bolts will do.... well.....

 

[GeorgeWBush]

Thanks Geraint.

How about the size of the beam (254x254x89 UKC) and padstones (600mmx100mmx300mm) and the bolts G8.8 M10? Is this a particularly large beam and does it 'seem' to be about the right size for the job?

I'm not a builder and have no experience of building - just concerned as to whether this will be up to the job?

I guess what I'm asking for is confirmation that this sounds about right.

 

[deanomy]

Beam and padstone calc's look good to me, the only thing I would be concerned about is the lateral stability (side to side) of the overall structure. The walls from side to side will act as shear walls resisting the wind load acting on the side of the building. The Engineer may well have considered this in her calculations and is probably OK, not a problem though as Building Control's checking engineer will check and should hopefully pick up on any potential problems like these. Not personally a big fan of bolting beams to padstones, though I guess it's up to the engineers preference. I have recently seen similar calc's the inner leaf of cavity wall was supported by 254x146x43 UB and the outer leaf a 260x90x35 PFC bolted together. I guess 2 small beam is easier to lift the 1 bigun.