Wall removed, rsj installed but failed on buckling resistance

[Trevor martin]

hi, long story cut short

We had a builder into remove wall in the kitchen. Who was ment to be qualified to self certificate his own work. But as you can guess was full of rubbish.

So contacted another builder who said the pad stones don’t look right. Get a structural engineer to draw a plan

Anyway we’ve had the plans back and the beam and pad stones are fine but he’s failed it on buckling resistance moment

Saying all we need to do is

Provide positive fixing between every 3rd joist and top flange of beam to enable effective length of 1.0 to be taken - beam adequate

Existing 178x102x19ub to be fixed to timber joists at every 3rd joist with heavy duty Simpsons strongtie brackets or ties positively fixed to top of ub and joists

I’ve looked at the said ties but there are loads of different designs any idea which I’d need?

Also am I right in thinking as we only need 2 brackets to have 1 going left and 1 going right.

As well fixing to the steel beam would I add wood in to the c by drill and bolt then screw the bracket to it

Thanks for any advice

 

[Trevor martin]

Pictures of drawings

 

[JohnD]

presumably you paid this structural engineer?

And he calculated something that is wrong, or at least disputed?

Surely it's up to him to get it agreed.

What if some anonymous numbskull on the internet tells you something wrong?

 

[Trevor martin]

Yes John But he has since stopped trading and vanished. Ive been chasing him for 18months
I’m just after advice to try and rectify the problem so we can move on with the rest of the renovation

 

[^woody^]

It could be something as simple as a right-angled bracket. Or if fixing timber to the web, then straping the joists to that should do. In either case, it may need noggins above the beam too.

 

[Trevor martin]

Much appreciated woody thank you

 

[John D v2.0]

The idea is to stop the beam twisting under load. By restraining the top flange of the beam it would prevent the twist. Sounds like you have to drill and screw into the beam, and strap it to the joists on either side. You can get various plates and brackets in Wickes or builders merchants so I'd just see if there's something that looks the right shape. Even a roll of builders band might be enough.
You can always check with the new SE to see whether your plan is adequate.
Ps I'm not a builder or an SE.

 

[^woody^]

Where's our resident Manchester SE when you need him?

 

[Notch7]

Where's our resident Manchester SE when you need him?

I think he maybe in Marble Arch

 

[Notch7]

We had a builder into remove wall in the kitchen. Who was ment to be qualified to self certificate his own work. But as you can guess was full of rubbish.

Ive never heard of a builder that can self certificate.......I mean there is a reason why SE study for years and pay PI insurance to underwrite their work.

There are very experienced builders who will have a good idea what steels maybe needed, but experienced builders will always say 'Ill build to your engineers details....'

 

[tony1851]

@op - looking at the plan, the span doesn't seem all that great, and a 178 x 102 seems not unreasonable without lateral restraint.

I suspect the problem for you is how the SE has worked out the effective length of the beam. The BS code states that the effective length should be taken as (1.2 x the actual length + the depth of the beam), and this makes the situation far worse for lateral buckling.

Eg if your span was - say 3.4 m, the spreadsheet the SE is working with will automatically increase it to (1.2 x 3.4 + 0.178 = 4.25m) which makes the buckling situation worse. If you look back through the figures, you will see this increase in effective length somewhere.

However, many SEs believe the increased figure is too conservative, and that it is perfectly OK to use the actual length as the effective length, particularly in domestic situations where the loads supported are not particularly high.

There was a paper published in the Structural Engineer magazine some years ago which addressed this issue, and showed how it is almost always OK to use the actual length for buckling purposes when supporting a timber floor. In the real world away from unimaginative spreadsheets, your beam could well be OK without messing about with restraints.

 

[^woody^]

I suspect the problem for you is how the SE has worked out the effective length of the beam. The BS code states that the effective length should be taken as (1.2 x the actual length + the depth of the beam), and this makes the situation far worse

Isn't EL span + 1/2 the bearings.

 

[^woody^]

I think he maybe in Marble Arch

I never had him down as someone who protests or argues.

 

[tony1851]

Isn't EL span + 1/2 the bearings.

For steel beams, it depends on the support conditions (eg whether bolted rigidly to some other member or just sitting on a padstone) and the way the loading is applied (eg resting on the top flange, or suspended from the bottom, as with a lifting hoist), or whether it is a cantilever.
The Code gives standards for different combinations.

 

[tony1851]

I never had him down as someone who protests or argues.

Only against Remainers or climate-change zealots.