bearing for steel?

[amwc]

Hi

I have to put a 7m steel onto a 100mm wide wall. I have been told now that I should have a pier because 100mm is not enough? Its got me questioning myself. Is 100mm enough?

cheers

 

[^woody^]

100mm can be enough ... unless someone who is experienced in beam design says otherwise

 

[MarkWG]

Needs at least 150mm in the (direction of the span) bearing onto masonry, and it should be a dense pad. But width wise it's less important, what size is the flange on the beam (guess its a 356 or 40something? depth) Is the beam restrained perpendicular to the span by joists ? Ultimately the contact of the beam on the top of the masonry is going to provide very little lateral restraint whether its 100 or 300mm, so it's down to the rest of the structure...

Ultimately I think it's a question for an SE, but you need to describe exactly how the beam is acting.

 

[noseall]

Needs at least 150mm in the (direction of the span) bearing onto masonry,

So what you are saying is at no time can a 7m long beam drop onto a 100mm wide wall?

Regards the original post:

Why on earth are you messing around with a 7m long beam without appropriate advice?

 

[amwc]

I have appropriate advice and a calc which shows that 100mm bearing is fine under a 254 UC. But people make mistakes and a discussion with a fellow had me questioning it.
Thanks for the replies I now know that 100mm is fine as the wall is restrained. I got confused by single skin walls and tied cavity walls

Its been a long day.

 

[MarkWG]

Needs at least 150mm in the (direction of the span) bearing onto masonry,

So what you are saying is at no time can a 7m long beam drop onto a 100mm wide wall?

No, it can width-wise, my point related to the bearing "length" of bearing I guess (in the direction of span, not in the width of the beam, as there is no hard and fast rule for the width; though if it was less than the flange of the beam I'd be worried...).

OP:

How can a 254 UC bear on a 100mm wall?

 

[amwc]

Like you say its bearing length the width of the wall is 6m
7N/mm pad stone underneath 440 215 x 100. The bearing under the beam is less than 2N so well in as they say.

 

[MarkWG]

There's also the compressive strength of the blockwork under the pad...

I'll be quiet.

But the question still remains, why are you using a 254mm UC? Is it to give a bearing to the joists? What's overhead? Wouldn't you be better off using a WF Beam, and saving a bit of weight...

 

[geraint]

Needs at least 150mm in the (direction of the span) bearing onto masonry, and it should be a dense pad. But width wise it's less important, what size is the flange on the beam (guess its a 356 or 40something? depth) Is the beam restrained perpendicular to the span by joists ? Ultimately the contact of the beam on the top of the masonry is going to provide very little lateral restraint whether its 100 or 300mm, so it's down to the rest of the structure...

Ultimately I think it's a question for an SE, but you need to describe exactly how the beam is acting.

would love to know where your information comes from....

 

[MarkWG]

The bearing I think is the corusinconstruction website. Cba to find a link.

 

[geraint]

whatever size steel.... it can sit on whatever sized wall it is designed to

100mm bearing is sufficient.

the 150mm statement throws people into panic...

how thick are your walls...

100mm

so how can your steel sit 150mm on a 100mm wall

 

[MarkWG]

Government planning portal, OK it's a sh1t source, but I can't find what I was looking for;

Beam(s)

Structural Support

The beam should be designed to cater for the loads that the wall was originally taking. This beam then needs to be supported on two other supports (typically walls) that are capable of taking the loads to foundations. Any new beam should normally have at least 150mm bearing (overlap onto the existing wall) on each side of the opening and the existing wall beneath the bearings are likely to need to be strengthened to prevent crushing of them. This may require the installation of an area of dense concrete (cast in-situ or pre-cast), known as a padstones to spread the load. The size of padstones will vary depending on the circumstances of the case in hand it is advisable to speak to a structural engineer or surveyor before starting any works.

 

[MarkWG]

whatever size steel.... it can sit on whatever sized wall it is designed to

100mm bearing is sufficient.

the 150mm statement throws people into panic...

how thick are your walls...

100mm

so how can your steel sit 150mm on a 100mm wall

Ah, I thought I made it clear (in each post), "in the direction of the span", but possibly this was missleading/useless information.

Perhaps the OP had been told that there was a minimum bearing, this is why I mentioned it...

I was trying to illustrate the point that there is no minimum width as it depends entirely on how the structure acts. It could bear on an inch if the beam was the right profile, it was restrained by what was above it, and the pad could take it.

 

[geraint]

whatever size steel.... it can sit on whatever sized wall it is designed to

100mm bearing is sufficient.

the 150mm statement throws people into panic...

how thick are your walls...

100mm

so how can your steel sit 150mm on a 100mm wall

Ah, I thought I made it clear (in each post), "in the direction of the span", but possibly this was missleading/useless information.

Perhaps the OP had been told that there was a minimum bearing, this is why I mentioned it...

I was trying to illustrate the point that there is no minimum width as it depends entirely on how the structure acts. It could bear on an inch if the beam was the right profile, it was restrained by what was above it, and the pad could take it.[/quot

would love to know the profile that would allow a bearing of an inch and the padstone size....

 

[geraint]

Needs at least 150mm in the (direction of the span) bearing onto masonry,

So what you are saying is at no time can a 7m long beam drop onto a 100mm wide wall?

No, it can width-wise, my point related to the bearing "length" of bearing I guess (in the direction of span, not in the width of the beam, as there is no hard and fast rule for the width; though if it was less than the flange of the beam I'd be worried...).

OP:

How can a 254 UC bear on a 100mm wall?

how can it not....