LSB Posted November 30, 2023 Share Posted November 30, 2023 Still getting a big bogged down on our suspended floor. Our SE drawings were fine, until we started to clear to underpin an existing single skin wall only to find it wasn't attached to the ground so was not viable. So, after all the hoops that involved getting permission to replace some unstable walls, which appeared stable on the initial class Q conversion survey. We then continued in our merry way and dug out, trench approved, and poured foundation. BCO came out as he wanted to check our mesh suspension and then insisted that we had new SE drawings to cater for cavity walls. Some cost and lots of time later we have the drawings as requested. All fine except he's included shear links. More back and forth as these seem to be unusual, we eventually got the code H33 and have found them. Apparently the H10 in the drawing just means bumpy steel. Right, my question, what do these actually do and what does 100mm cts mean. I guess they sit 90 degrees out from the wall partly on top of the foundation and partly within the mesh. This is for a single storey barn conversion, not the rebuild of Luton Airport carpark Any info greatly received. Link to comment Share on other sites More sharing options...
Tom Posted November 30, 2023 Share Posted November 30, 2023 Think yourself lucky, our suspended slab ended up with FOUR layers of A393 mesh. No idea re shear links though, sorry, but 100mm cts means 100mm centres, so spaced every 10cm. 1 Link to comment Share on other sites More sharing options...
Mr Punter Posted November 30, 2023 Share Posted November 30, 2023 5 minutes ago, LSB said: and what does 100mm cts mean. cts = centres, so 100mm apart. You can get the links fabricated as you will need a fair few. 1 Link to comment Share on other sites More sharing options...
markc Posted November 30, 2023 Share Posted November 30, 2023 Shear links or stirrups are used to hold bars to form a cage for a ring beam 1 Link to comment Share on other sites More sharing options...
LSB Posted November 30, 2023 Author Share Posted November 30, 2023 1 hour ago, Tom said: Think yourself lucky, our suspended slab ended up with FOUR layers of A393 mesh. No idea re shear links though, sorry, but 100mm cts means 100mm centres, so spaced every 10cm. why 4 layers, what are you building Link to comment Share on other sites More sharing options...
Tom Posted November 30, 2023 Share Posted November 30, 2023 4 hours ago, LSB said: why 4 layers, what are you building tank museum 2 Link to comment Share on other sites More sharing options...
George Posted December 1, 2023 Share Posted December 1, 2023 Shear links increase the slabs resistance to shear. That is, it's resistance to snapping at the support. Because the slab is supported on cellcore it is actually a suspended slab, because the cellcore can be crushed by ground heave and no longer support the slab. It is essentially a sacrificial falsework. Because it is suspended the assumed support is just on the edge of the foundation. Sometimes slabs can be made thicker and no longer need shear links (because with more concrete you don't need the steel to resist shear) but it is a balance concrete cost Vs steel cost. Cellcore also has a limit on wet concrete thickness so you may need to go up a grade with that too. Steel suppliers can prebend reinforcement to a given dimension so you just need to order the links. 1 Link to comment Share on other sites More sharing options...
MartinGT Posted December 3, 2023 Share Posted December 3, 2023 H10 is a 10mm Ø rebar. If they're giving you that information they should be at least supplying you with either a RC drawing or a Bar Schedule so you can give that information to a bar bender. It should take them 10 minutes to give you that information. It's straight forward. Although they have specified a B705 mesh. It should be B785 mesh! Have they specified which way the mesh is spanning? B mesh has a set of main bars (in this case 10mm Ø at 100mm centres) and distribution bars (in this case 8mmØ at 200mm centres). The main bars should span the way they've designed the span of the suspended slab for. Now it may be the case it's not critical but it's worth asking. 1 Link to comment Share on other sites More sharing options...
LSB Posted December 3, 2023 Author Share Posted December 3, 2023 11 minutes ago, MartinGT said: H10 is a 10mm Ø rebar. If they're giving you that information they should be at least supplying you with either a RC drawing or a Bar Schedule so you can give that information to a bar bender. It should take them 10 minutes to give you that information. It's straight forward. Although they have specified a B705 mesh. It should be B785 mesh! Have they specified which way the mesh is spanning? B mesh has a set of main bars (in this case 10mm Ø at 100mm centres) and distribution bars (in this case 8mmØ at 200mm centres). The main bars should span the way they've designed the span of the suspended slab for. Now it may be the case it's not critical but it's worth asking. Hi, we went thru the B705 v B785 a while ago, the SE just didn't update this bit of drawing. They also provided full details of the mesh and Shear Links, I just didn't know what they did, so I was trying to educate myself. They have designed the mesh to go in a particular direction, basically side to side, although it is only the sides that take the weight all 4 sides have the rebar on top. The conversion has 3 sizes of rebar in different areas, underpinning in shallow foundations and secondary foundations where they don't think there is enough bearing size for the rebar. All in all quite complex drawings, not helped in the least by them making typo mistakes like B705 when I'm trying to get best price. Thanks for you help. 1 Link to comment Share on other sites More sharing options...
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