steel beam width not matching the block width

[StructMind]

I have a 254x146x43 steel beam sitting along a block inner wall of 100 mm wide and 300 mm long at one end. So it is about 23 mm stick out on both wings.

On top of the beam, I will have a block inner wall of 100 mm wide to the whole beam length as well. Builder think that the beam width and block width under the beam should match. But there is no load passing the bottom flange with plenty of bearing capacity (300 x100) and the top flange is only partially covered anyway. Any comment from your past experirnce would be useful.

 

[noseall]

What's your question?

 

[RonnyRaygun]

Could you push the beams together so that there is no outstand? The load would be marginally off centre but I don't see that being an issue.
If it does concern you check the web for the additional bending induced or add some stiffeners?

Or could you use a 203 or 254 UC with a top plate?

 

[tony1851]

As above, not sure about the question, but the diagram shows an odd way of doing it. How is your builder going to get
bricks/blocks between the beams? Again as above, just butt them together, the offset won't matter on that scale. Or as advised
use one UC section + plate.

 

[StructMind]

The beams were install ed already. It was designed without eccentric ity with usage of 0.8. the torsion will lead to 10percent usage. I suppose it will still work but not ideal. Would it be better to have the outstand and the load are centric?

 

[tony1851]

It was designed without eccentric ity with usage of 0.8. the torsion will lead to 10percent usage.

?

 

[StructMind]

Yes a calculation including the extra torsion from eccentric cavity wall and minor axis bending gives 0.1 additional utilisation ratio. The as designed beam without eccentric ity has .81 utilisation ratio.

 

[^woody^]

Lol, where are the padstones instead of hollow bricks for a bearing.

Has this even been designed by an engineer to UK building design methods?

 

[tony1851]

What's the span, and what sort of loading?

Wouldn't two 203 x 102s have done?

 

[StructMind]

Builder said it would be better for him to put padstones afterwards. The span is 6 m hence 2 big 254x146x43 ub. I have two options 1 leave as is but accept the additional torsion, option 2 move the beams cejtric but accept the outstand

 

[^woody^]

It looks like beams have a full bearing on the first section of internal wall, and the parts of the beam projecting further past that 100mm are irrelevant. In one sense, the beams are too long.

It's probably the same at the other end

The slight offset of the wall above is not a big deal.

But normally, the beams would be bolted together as a load sharing beam, not just butted.

 

[StructMind]

All thank you. This is the other end. It is fully beared to the internal wall. The bearing is not a problem as Padstones are to be placed. The problem are which options to choose 1 to keep as it is now but accept the eccentric loading from the cavity wall above, or 2 move the beams to align their centre lines with the walls but accept the outstand and two beams not bolted fully as the spacers are short. Please advise.

 

[RonnyRaygun]

As I said earlier, if it looks like the torsion calc shows that the beams are marginally over-utilised, and this concerns you, weld in some stiffeners between the flange on the visible faces. That way the webs can't bend laterally because the stiffeners are there to stop it happening.

Alternatively, rather than simply bolting the beams together, bolt short stubs of 150x75 PFC between the webs which, if done correctly, will also stop the webs bending.

 

[StructMind]

Thanks Ronnie. The beams are installed hence it would be difficult to put the pfc on. The torsion callc gives 0.1 additional utilisation but the total is less than 1.0 i am struggling if i should ask the builder to move the beams to align with the center of the walls but with outstand and lack of connection between thw two beams as the spacers will not be effective or leave it.

 

[RonnyRaygun]

If the total utilisation is less than 1 I certainly wouldn't be worrying about it. By the time you've added in all the factors of safety too there is plenty of spare capacity. There's usually a bit of allowance in the loadings too.