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  • lazar
    Participant
      June 26, 2009 at 10:46 am #2980
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      hi all…

      is there any difference between a beam (1500mmx600mm, bxh ) with tendon with vertical profile (the usual beam profile, high point at support and low point at midspan) and a beam with horizontal profile, meaning that 1500mm became h and 600mm is the width, b. Is the action of the beam the same during stressing?

      hope to hear from you guys….

      best regards

      AnonymousPosts: 49
        June 26, 2009 at 1:00 pm #3254

        There is a difference:
        1.profiling -> change of uplift from tendons, deflection, tendon forces – major difference;
        2.position of tendons (in midspan& @supports: if ducts occupy more than 40% of the width->troubles) and anchors (arrangement@a stressing face of the beam);
        3.depth – 1500 may not be very welcome in a residential building!

        ahmed
        Participant
        Posts: 31
          June 28, 2009 at 8:33 am #3257
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          The main thing is related to the beam capacity.If depth is more capcity will be more.The main aim of suggesting a PT beam is to reduce the depth.If the depth is more and no floating column loads no need for PT in that beam.if we provide more depth headroom will be less.

          lazar
          Participant
          Posts: 31
            June 28, 2009 at 9:58 am #3259
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            it's not a residential one (sorry for giving incomplete info..)…the beam will resists a hydrostatic pressure. It's like a cap beam in a wall (located at the top of the wall)….

            thanks….

            AnonymousPosts: 49
              June 28, 2009 at 12:32 pm #3260

              Then this should be fine.

              You can “rotate” the whole beam to resist horizontal forces. The design is no different from a “normal” vertical design (apart from selfweight).

              You should consider durability as the most important – try to avoid cracking as much as possible (including early thermal cracking&shrinkage).
              Proper aggregate choice and compaction on site may be essential too.

              Sorry if the stuff above is “too obvious” – I'm dealing with a PT tank design now and I've just learnt about quite a few failures due to “bad concrete”.

              Decipher
              Participant
              Posts: 46
                June 28, 2009 at 2:21 pm #3258
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                Interesting!.

                I am not sure what you are trying to achieve, but i understand (from limited info you gave) that the beam is resisting “horizontal” force (i.e. hydrostatic pressure) and it is on top of a “wall”. Is that correct? or is the beam part of taller wall (like you took a slab with beams and rotate 90 degrees and put it upright). Hard to picture you are trying to acheive.

                In any case, one thing is for sure. You need to go back to the basic mechanics and model the beam because you have two lines of force actions here. You have the regular vertical dead load (self-weight) and now your live load is horizontal (water pressure). When acting together, you have a resultant and you got warping/torsion effects too which could be very insignificant that you could ignore them (but got keep that in mind)

                Think of a tank design.

                If not provide a quick sketch and we could contribute ideas. Seems to me special cases.