Bearing plates...

[jmgh]

Hi,

After a bit of reassurance regarding steel bearing plates.

I have been recommended a builder and structural engineer. They have worked together in the past for a good friend of mine.

The builder requested that I ask the se to spec steel bearing plates rather than concrete padstones (less masonry to remove). So far so good.

One of the beams going in is a 203x203 UC 46 spanning approx 4.5M with 100mm bearing at either end on the party walls.

The bearing plates specified are 1000x100x50!!!mm thick.

Does this seem right? Seems massive to me and is not going to be cheap.

Just wondering if anyone's heard of using bearing plates this big.

Any opinions would be appreciated, just to put my mind at ease.

Many thanks.

J

 

[^woody^]

Did you ask him to design a bearing plate or armour plate?

It looks like a fair sized beam with perhaps above average bearing stress, but 50mm seems like someone may be being a bit lazy and a bit over-cautious with his calculations

 

[RonnyRaygun]

...someone may be being a bit lazy and a bit over-cautious with his calculations

A bit!! Either that or someone has made a cock up!

No, you won't need a bearing plate anywhere near that size.

It wouldn't need to be any longer than a pad stone, and even in poor brickwork, these usually don't need to be any longer than around 550mm, often less.

Also, the thickness of the steel is usually no more than 30mm max.

Obviously without knowing the load from the beam and masonry type we can't be sure, but no way do you need a 1m x 50mm thick bearer.

 

[jmgh]

Hmmm.

Thank you both, I thought as much...

As for the loads, its a 2 up 2 down victorian terrace built circa 1895. There will be no masonry load on this beam. the 1st floor will bear on it, and also the roof, but I wouldn't have thought the loads would be extreme.

So, how to broach this with the SE... ? Its a tough one.

J

 

[RonnyRaygun]

So, how to broach this with the SE... ? Its a tough one.

J

Yeah, people often don't like having their work questioned by a layman, but it's so glaringly obviously wrong...

Just say something like "The bearing plates seem a bit large. I was wondering if they are the correct size? My builder said he's never installed plated of that size. Would you mind checking for me as the steel will be very expensive."

I've just checked one of my old jobs. A steel plate carrying 50kN and that was only 450x100x25mm thk. I can't imagine that your beam reaction is much, if any, more than that.

 

[jmgh]

Thanks again Ronny,

I'll give him a call and let you know how I get on..

J

 

[jmgh]

Right, I've looked at his drawings, and they state that the KN loading on each end is 45.66... Was your loading a total (ie 25 each end) or 50KN each end?

J

 

[RonnyRaygun]

Right, I've looked at his drawings, and they state that the KN loading on each end is 45.66... Was your loading a total (ie 25 each end) or 50KN each end?

J

My loading was 50kN at the end of the beam.

Your loading may possibly need to be factored but even then the plate size is way too big.

 

[jmgh]

Haven't heard back from him yet, but his prosteel calcs seem to back him up on this...

 

[RonnyRaygun]

Haven't heard back from him yet, but his prosteel calcs seem to back him up on this...

You might need a 1m long spreader if you are building on jelly...

No way do you need a 1m spreader if building on masonry (even crap masonry).

This is the danger of blindly accepting what a computer program tells you, without taking a few minutes to think about the results

 

[jmgh]

Thanks again ronny. It's a bit of a bind isn't it. You need the se for these calcs and have to go with what he specs to be insured etc. dont suppose building control would ever down spec an element... even my steel supplier thought this was crazy. Will let you know what his response is.

J

 

[jmgh]

Thanks again ronny. It's a bit of a bind isn't it. You need the se for these calcs and have to go with what he specs to be insured etc. dont suppose building control would ever down spec an element... even my steel supplier thought this was crazy. Will let you know what his response is.

J

 

[themiddleagedun]

Instead of all this faffing around, just tell the builder to shove a concrete padstone in. It's a doddle of a job

 

[jmgh]

Well, just talked it through with him, and he's convinced.

Said he raised an eyebrow too when the software gave him those dims, but he checked by hand and it was right. Stated that there was roof loading, floor loading and a potential mezzanine on the attic deck... all adds up.

So, I'm going to ask the builder if he still want to use bearing plates instead of precast lintels knowing that the plates will weigh 40 odd kilos... Though I expect the relevant lintel would weigh even more...

Thanks for all your replies.

John.

 

[jmgh]

Managed to haggle him down to 45mm!