It must be more than just the nosing nib if the steel bar has been cut surely?
Damaged reinforced concrete lintel - what to do?
- Thread starter Beginerz
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Hard to tell from the pic but woody seems to think it is. Does the beam ( as that what it looks like) support bwk directly above it i.e. there isn't a projecting nib as such. If it does then severing a length of steel in the tension face of a RC beam is not to be recommended. Having said that there are all sort of FoS included in the design, be it actual loading, strength of concrete or reinforcement, so as stated, the test of time resulting in no undue visible issues should ease your worries somewhat, but nothing is black and white. If its any consolation at least its not in the middle of the beam where the BM would be at its greatest but at the edge where whilst shear is at its greatest there the reinforcement in that area tends to be due to the continuation of the bars designed to resist bending and as such the actual shear resistance provided is several times greater than that actually required.
Can I ask what a projecting nib is just to clarify?
If it means some of the concrete which forms part of the lintel sticks out/protrudes from the wall somewhat then yes this is the case. Probably an inch or more sticks out and from the underside where the lintel is good and not been touched, and there is a slight groove under the whole length just inside the underside edge.
However the steel rod from what I can see is not within the nib part but sits just inside the part which would support the bricks.
I would think it's supporting the bricks above certainly the outer skin, possibly the inner skin and maybe the first floor level above too depending where the weight of the floor beams is directed? Not sure if some of the roof weight could being directed towards the front and rear walls of the house or whether this would all be directed towards the side walls?
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The beam actually continues all the way along the semi detached through to the very end of next door's house. All the way along the semi detached structure.
So effectively the cut in the steel is quite near the middle of the whole beam if it is deemed to be one beam running through both properties.
Also next door have a conservatory and it looks to me like the lintel/beam has been damaged there too where their conservatory is attached to the house. I can't see if the steel has been cut on their side as it's covered with flashing but there's a sizeable gap in the lintel where it's certainly been knocked back at the least to fit their conservatory flush and the steel could well have been cut there too to be honest.
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In that case I think we can safely say the structural integrity of the beam has been compromise but to what extent and to what effect is open to debate. Go with test of time, FoS involved and probably over designed in the 1st place
It's a slab, not a beam and damage to small local areas do not affect the performance as a whole.
After more than 30 years, what signs of movement are there to the rest of the slab and the wall above?
None? Then just patch it a previous post and move on.
After more than 30 years, what signs of movement are there to the rest of the slab and the wall above?
None? Then just patch it a previous post and move on.
The outer wall does not support the floor or roof, that is all done by the inner wall, and the damage to the beam is nowhere near it.
The outer is just a weatherproof skin, it only has to hold itself up. Remember that the bricks aren't made of jelly, they can support themselves to a degree. If you completely removed all support under that corner then perhaps 3 bricks would fall out, the interlocking bricks above would hold the rest.
The outer is just a weatherproof skin, it only has to hold itself up. Remember that the bricks aren't made of jelly, they can support themselves to a degree. If you completely removed all support under that corner then perhaps 3 bricks would fall out, the interlocking bricks above would hold the rest.
The inner leaf is the one that does the real work, and it is fine...
IMO the disruption and further damage from any structural repair efforts would be far more likely to cause damage than just leaving it alone and patching up.
IMO the disruption and further damage from any structural repair efforts would be far more likely to cause damage than just leaving it alone and patching up.
Thanks. Out of interest what is the difference between a slab and a beam?
Very informative, thanks. I wonder if that's why it does seem to be proving the test of time so far, because most of the structural weight via the inner bricks is being put onto the in tact inner part of the lintel.
Would you all still stand by recommending a rust repair before patching up?
Also with the theory of helical bars being fitted in two rows further up and above, would they ever be suitable for something like this should some issues ever show themselves later?
Cement preserves steel, so normally nothing is used. In fact reinforcing steel is deliberately left to rust so it's rough enough to be gripped.
But you'd be better off with the epoxy recommended earlier instead of cement for a patch. In which case treat it. Kurust was the stuff once, there's probably other similar/better other stuff available.
Heilcal bars sound like a good idea, but not sure about the risk of disruption by fitting them right now. You'd be gouging out what's probably holding it together. Bit of a judgement thing needed there.
But you'd be better off with the epoxy recommended earlier instead of cement for a patch. In which case treat it. Kurust was the stuff once, there's probably other similar/better other stuff available.
Heilcal bars sound like a good idea, but not sure about the risk of disruption by fitting them right now. You'd be gouging out what's probably holding it together. Bit of a judgement thing needed there.
It goes rusty sometime because its left lying around whilst waiting to be fixed, clean bars ( usually high yield with ribs for extra grip) will arrive one day and can be fixed and concreted within a week
I look forward to Woodys answer to that with bated breath
Pretty sure some surface rust is an advantage, and intentional as it wouldn't grip as well if fresh and shiny.
But not relevant to the topic anyway.
But not relevant to the topic anyway.
Looking at it logically if there is a bit of rusty metal.you can sometimes wipe your hands across it and come away with brown stained hands, or taking it a bit further a wire brush or emery cloth will easily dislodge any well developed rust, why. , because its not chemically attached to the virgin steel which you can brush and rub all day for negligible effect. I have never seen anything in a spec where it says, in the middle of a dry summer the proposed reinforcement must be sprayed with water at suitable intervals to develop a nice bonding coat of rust for the concrete, but to be fair I haven't seen a clause where it says in winter it must be protected from the elements to prevent rust either. Ford cortina MK 2 or Nissan Qashqui
I don't know. It was stated to me when I briefly studied Civil Engineering decades ago but it may not be the case any more and I'm not going hunting for references.
My point is that rust into concrete is OK as the cement preserves it. But if not using cement then it will need rustproofing or it will become a big orange stain over the years.
My point is that rust into concrete is OK as the cement preserves it. But if not using cement then it will need rustproofing or it will become a big orange stain over the years.
Quite agree no issue with rusty bars being surrounded in concrete as if dense/thick enough it will prevent further attack by moisture,more rust forming thus expanding thus spalling concrete with associated rust stains
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