ReinisGailitis

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About ReinisGailitis

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  • Birthday 09/25/89

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    Riga, Latvia
  1. I'm not sure about ACI and CSA guidelines, although it seems obvious that if there is compression stress spread there is tension which should be carried by reinforcement. Anyway, EC2 allows increase of up to 3 times of the design strength of concrete for crushing and spalling resistance (first potential failure mechanism) of the "partially" loaded area but the designer also needs to check the area for bursting (second potential failure mechanism), which should generally be done by strut-and-tie design of adequate reinforcement. If this reinforcement is provided and bursting is not the governing failure mechanism, then one can take advantage of the increased crushing/spalling resistance. Not particularly allowed by EC, but "FIB Model Code 1990" (which is basically the basis of EC) allowed potentially increased bursting capacity for bulging compressive struts (which basically is this "partially" loaded area case where compression stresses spread out in a larger area) which are not adequately reinforced and the capacity (allowable bearing pressure) was influenced by the geometry of the bulging strut and the design tensile strength of the concrete. Of course this method could only be used for regions which where not expected to crack in the life of the structure because of any other influences/actions like shrinkage, etc. If cracking was expected and no bursting reinforcement provided then the bearing pressures allowed would be (by EC) around 53% of concrete compressive design strength.
  2. Eurocode allows for up to three times the design compressive strength of concrete if you provide adequate reinforcement. Cheers
  3. No - you need to report them!
  4. I would suggest you to have provide more information on the clauses you're referring to. Anyway I don't understand what you're talking about here. If you want to check masonry in local compression to Eurocode 6 then there is particular method for that presented in the standard.
  5. You can find them on internet if you put in some time. I have found them once. Cheers
  6. You should be able to find everything you need in this document: http://www.eurocodes.fi/1993/1993-1-10/background/EUR_23510_EN[1].pdf Cheers
  7. Oh, I see what you're talking about, then yes, it is definitely a ground beam not a typical pile cap. In such a situation the load transfer is basically one-directional, so punching shear failure as in a two-way slab cannot occur as the beam is not wide enough, to cause significant distribution of forces around the pile, as you'll see from a strut and tie model, where the last diagonal strut transferring the load from the span will taper to meet the force from the pile. Cheers
  8. This is not a simple question to answer with a simple answer, but in general you could argue that this is the case, as EC2 permits one to take into account a high pressure underneath foundations. Anyway, it really comes down to geometry of the structure. There are no guidelines provided in EC2 for you to make such a decision, so you should look for alternative sources of info or decide based on your own knowledge of the behavior of slabs on columns (or vice versa). P.S. Just to check - are you referring to a ground beam a.k.a. pile cap? Cheers
  9. If the beams are not really wide then punching shear failure will not be possible - the beams may only fail by beam type shear. Cheers
  10. The particular one you posted is just a commentary and does not contain a pdf file or similar. There are some AD's that are written in this way and are posted only as written info, others are pdf. All AD's are quite short, 1 to possibly 3 pages. Cheers
  11. In the lower part of each of the descriptions there is a link to open a pdf file with full info.
  12. Try different browser. Also, have you tried just the www.newsteelconstruction.com ?
  13. I'll repeat myself - go and download them, they're free to everyone - http://www.newsteelconstruction.com/wp/category/tech/ad/ Cheers
  14. Go to http://www.newsteelconstruction.com/wp/ and download the yourself. Cheers
  15. From my knowledge I would say yes, if you pour the slab in two pours and allow long enough time between them the lower part of the slab should shrink a considerable rate leaving only a small residual shrinkage strain to take place after second pour is constructed. One must consider the fact that the actual thickness of the second pour will be more that 250mm, as the lower part of the slab, which was poured to 250mm thickness now is thinner because of shrinkage. Also one should consider the residual shrinkage strain to take place after second part of the slab is constructed. I suppose that if you could show by simple analysis on realistic assumptions that in this situation the shrinkage to which the top steel of the second pour is subjected is equal or just a little higher than one which would prevail in a single pour slab of 250mm, than you may assume good bond conditions. I would think that the margin for this assumption would have to be small, the usual 5% for example, as there are too many factors not really known in design, which will influence the was concrete cures etc. Although if you have to wait a certain time for the first part of the slab to cure before concreting the second you could start having problems with shrinkage strain induced tension from restraint on the top surface of the slab from first pour which would require you to provide some nominal reinforcement, which I suppose would mitigate any economic benefit from using smaller lap lengths in the top steel of the second part of the slab which is poured in the second stage, because if you don't provide reinforcement to control cracking, you may find the slab cracks substantially and possibly reduced slabs resistance to shear force, which may pose a significant threat if there are no links provided. Anyway this is all just from my theoretical understanding of the problem and the only way to know and really "show" that all of this is true is by testing. Cheers