Steel and joists

[liam546]

I have put in a steel beam today which is bolted to two steel posts which in turn sit on pad stones under the floor. On the bottom of the steel is also welded a plate for the joist to sit on. I'm an hiding the steel within the floor so have cut the joists.

However the joist closest to the wall we had to cut short in order to get the post in. I now have a joists floating mid air (currently under acrow prop) I need to support as the length is now not long enough to fit on the steel.

Could I coach bolt or anchor bolt with resin to the wall instead? Or what is best solution? You can see in pic below at the top right where the joist is now short

Untitled

• liam546
• 18 Jan 2014
• 1

 

[Norcon]

Whats the white thing the prop is leaning against?

A big angle plate with a gusset and bolted against the wall would hold them good and proper.

 

[liam546]

Thanks for reply, the white thing is actually just the wall, but painted plaster. It looks deceiving in pic i know.

Would you use chemical anchor bolts with the resin?

 

[Norcon]

Thunder bolts.

 

[liam546]

I've just looked up thunderbolts. Not used them before.

My bricks are a type of brick with around 16 hollow holes in them. It's annoying because whenever I drill into my bricks they just crack and split as the hollow holes cause this to happen. Which is why I initially thought of resin and studs.

Do you think thunderbolts will be ok for this type of brick

 

[Norcon]

I'd plug the hole with resin and then screw in the thunder bolt.

Will be there for eternity.

 

[Rosco906]

I wouldn't use a thunder bolt with resin,

I would drill hole, stick in a bolt/threaded rod, wait till the resin goes off and stick on a nut and washer,

Sticking a thunder bolt into wet resin won't do nothing.

 

[liam546]

Would a couple of M12 threaded rods be ok for this 1st floor joist that needs supporting? .......with about 100mm going into the brick face

 

[loply]

Why not just extend the joist?

 

[liam546]

Well yes....if I could extend the joist to also sit on the steel that would be great but I wasn't sure if it was sensible or if there was a practical way of joining timber to timber and extending the joist whilst still maintaining its strength and stability.

Id like to hear some solutions please if you have any?

 

[loply]

I thought there may have been a reason you couldn't.

Just get a matching piece of joist (or laminate one from plywood). Attach initially with nail plate to hold it, then reinforce with an overlapping piece of joist say 300mm each side screwed in with say 5 decent screws (like 10mm thick things) each side.

It would be ideal to reinforce it with an overlapping piece on each side but it looks like you won't have space.

Either way the result will be stronger than the original joist in all likelihood.

 

[Rosco906]

I'm not sure if it would work but when we have to join big beams we have chunky steel plates either side of the beam and usually m20 bolts but with wood if imagine you could get away with 4 m12's with steel plates either side?

 

[loply]

I don't think the size of the fixing is that important, an M10 bolt will not shear with the loads involved, the joist would split long before 10x M10 bolts would shear! You'd need thousands of tons on there...

The important part is over what distance the load if distributed ie how far apart the fixings are. The danger is that the fixings will split the wood when loaded.

I suggested overlapping 300mm each side, maybe go 500mm or 600mm if in doubt. That way the joint is 1m long in total.

Would take a pretty incredible force to break that...

 

[liam546]

Thank you for all the advice.....Loply I'm thinking yoir idea us the best as a 1 meter long fixing or joint I'd imagine should be a lot stronger than if I bolt existing joist to wall or use a shorter steel plate to join the timber. I'd worry the two later may split the wood under load.

By making the joint longer using two bits of timber each side of the joint snd fixing with screws or bolts I think this sounds the most solid solution.

Thanks again for all advice.

 

[Norcon]

I wouldn't use a thunder bolt with resin,

I would drill hole, stick in a bolt/threaded rod, wait till the resin goes off and stick on a nut and washer,

Sticking a thunder bolt into wet resin won't do nothing.

Garbage.
A thunder bolt hold' s because of the friction between the spirals and the aggregates.
When the aggregates are porous or void then any addition applied via chemical application or otherwise to help increase the density of the substrate will automatically increase the holding force.