Clipping the end of a steel / Structural Issue

[RichA]

My beams needed to be adjusted for the roof line. Is this an issue?

When does a cut out become too much?

Thanks.

 

[tomfe]

Ask your SE, we can only guess on here.

There must not be too much weight on it as it's sat on your wall plate and not on a pad stone. It's all really about deflection and I doubt that cut will make any difference.

 

[noseall]

It should be sitting on masonry not wood.

 

[tony1851]

The cut out is not an issue; it will not affect the bending stress or deflection of the beam. The only criterion at the support is the shear force, and there is plenty of material left in the web to sustain any likely shear load.
If the load the beam is supporting is not excessive, there is no problem supporting it off the wall plate.

 

[Leofric]

I would agree with some of the earlier posts that a steel beam should sit on a concrete padstone at each end. I have never know steelwork to sit on timber and structural engineers always specify steel beams sitting on masonry walls should bear on to dense concrete padstones ,in addition they specify the dimensions of the padstones to suit the loadings on the beam and the compressive strength of the blockwork or brickwork the padstones sit on.

 

[tony1851]

I would agree with some of the earlier posts that a steel beam should sit on a concrete padstone at each end. I have never know steelwork to sit on timber and structural engineers always specify steel beams sitting on masonry walls should bear on to dense concrete padstones ,in addition they specify the dimensions of the padstones to suit the loadings on the beam and the compressive strength of the blockwork or brickwork the padstones sit on.

If the beam is not heavily loaded, it is no problem sitting it directy on a wall plate.
As an example; the beam in the OPs pic looks to be a 203 x 102 UB. The direct contact area is therefore (width of flange) x (width of wall plate)
= 102 x 100
= 10,200 mm².

1 sq mm of C16 timber can sustain a load of 2.2 N/mm² perpendicular to the grain (assuming there is no local wane).
Therefore in this case, the reaction at the bearing of the beam could be up to 10,200 x 2.2 = 22.4 Kn.
Obviously we don't know the load the beam is carrying but if it was a uniform load, it could support around 44KN.

So why do SEs "always specify steel beams sitting on masonry walls should bear on....padsones"?
Answer: because some lack imagination.

 

[SFK]

Tony,
Fully agree with your maths.
But looking at the above photo I would be worried in case that wall plate gets damp and rots at some point in future.
Especially as I think I can see the steel sitting on top of the joint of two separate wall plates.
SFK

 

[noseall]

Especially as I think I can see the steel sitting on top of the joint of two separate wall plates

I thought that initially. Rather, it looks more like where he has nicked the plate with the angle grinder whilst attacking the end of the steel.

 

[tony1851]

Tony,
Fully agree with your maths.
But looking at the above photo I would be worried in case that wall plate gets damp and rots at some point in future.
Especially as I think I can see the steel sitting on top of the joint of two separate wall plates.
SFK

I suspect that if the wall plate got damp and rotted, the OP would have more important problems to worry about!

Don't know if the wall plates are separate (Nose seems to suspect not) but there are safety factors built into the figures for allowable stress
so I doubt that would be an issue.

I'm not doubting Leofric's point about steel beams bearing on proper padstones - and the vast majority I detail DO have properly-sized pads.
But there are plenty of instances in this game in which things 'work' even though not done strictly by the book.

 

[^woody^]

Who the hell designs a beam to stick out of a roof? And is he related to the buffoon who just randomly takes an angle grinder to it?

Beams can sit on timber, just like they do in timber framed buildings. The real question is "should they?"

 

[Leofric]

RichA, just out of interest what structure is the steel beam supporting ?
Regards

 

[RichA]

Thanks for all your comments. This beam is on the 2nd floor of a new 2-storey extension. It supports a post, that supports one end of 1 of 3 cranked beams that support the new roof.

See calcs for this beam below.

If it requires masonary/padstone what action is necessary? Do you simply remove, a say 300mm, section of timber plate and replace with a concrete padstone?

View attachment 153835

 

[^woody^]

Lol ... Superbeam. That was not designed by an engineer.

 

[bobasd]

as above, steel is still used in timber framing
but glulams or similar are nowadaysused more.
IME, steel pressure points/seatings usuly suppoerted on posts - custom or built-up.

thers no need for any masonry/padstone - just fix a 4"x4" or a couple of sisteredstuds direct below the top plate all the way down to the bottom plate or sill.
all joist seats should sit direct above studs or cripples.

 

[noseall]

Who the hell designs a beam to stick out of a roof?

I'm guessing he didn't. I'll wager it was an on-site decision to position the beam within the floor space. Designer prolly had it down in to the room below.