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  1. NAFTALI-HAKOHEN

    [img https://res.cloudinary.com/eng

    Hi all, Am designing a reinforced concrete wall, with large window-hole, as per revit sketch above, Large line loads on the wall, roughly 1300 kn per metre length,(slabs at upper level and lower level of wall) Am not sure how to HAND CALCULATE the global behaviour of the wall, ie moments and...
  2. NAFTALI-HAKOHEN

    Cracks in Concrete Beam

    Hi all I happened upon a concrete beam, that connects between two large new residential buildings. Each building around 6 stories. The beam is only taking its self weight, and has visible cracks at the beam underside, at the connection point to the wall. Was wondering why the cracks are on...
  3. NAFTALI-HAKOHEN

    Offset Transfer Columns in Thick PT Slabs

    I think youve seriously overcomplicated your calculations! And my calculation gives a larger value for the horizontal tension and compression in the slab (836kn) see attached calculation The horizontal slab forces need to be resolved with a view to the larger structure ( next bays/frames etc)...
  4. NAFTALI-HAKOHEN

    Amount of Construction in US/Europe?

    Hi all, Im struggling to find reliable resources on how much square foot of construction is done in US every year? And specifically how much steel deck composite slabs (sq. ft ) is constructed per year? Does anyone have reliable info or a good estimate? Thanks NAftali
  5. NAFTALI-HAKOHEN

    Vibration Analysis in Long Span Slab

    OP here Thanks for response, the short term deflection is 2-3cm, which gives frequency of 3-4Hz which compares somewhat with the FE results The slab is a kind of museum/ study area in a University campus The slab mass is very large, but the span is also large! The interaction between this...
  6. NAFTALI-HAKOHEN

    Vibration Analysis in Long Span Slab

    HI all, Im designing a concrete reinforced slab (not PT) , for a large span 32metres by 26metres, supported by thick (45cm) concrete walls) and have few questions regarding vibrations. The slab thickness is 79cm (extra dead load 1kPa and live is 3kPa) The FE analysis shows natural frequency...
  7. NAFTALI-HAKOHEN

    Post-tensioned Slabs - Long term effects

    Hi all, I have studied PT design in the past but am new to the actual live design practice of designing PT slabs, What are the long term issues with PT slabs that i should be aware/familiar with, and what types of failures are most common? Thanks Naftali
  8. NAFTALI-HAKOHEN

    Top reinforcement in slabs - Minimum Rebar

    Hi, Im looking for a clear reference to minimum rebar requirements, in the upper layer of a large span , that has only sagging moments in the centre of the span, ie there is no structural purpose for this rebar. (i see that 50% of steel required for sagging moments must extend to external...
  9. NAFTALI-HAKOHEN

    Curved concrete walls (kind of Hyperbolic Parabaloid)

    Hi all, Im designing a very large concrete wall for a public building (museum), that is curved in 2 directions: Dimensions of the wall are around 35m length and 20 metres high (at the peak) , and the architect has modelled it in Rhino , so i have the exact dimensions (NURBS surface properties...
  10. NAFTALI-HAKOHEN

    STRESS DISTRIBUTION IN BEAM WITH SMALL 'TEETH'

    hi all, thanks for the responses, it is a concrete beam loaded from above, and ill try post the FEM when i get to office tomorrow, there seems to be some agreement here that due to the shear lag around these corners, the tension will certainly be less than at continuous part of beam, even...
  11. NAFTALI-HAKOHEN

    STRESS DISTRIBUTION IN BEAM WITH SMALL 'TEETH'

    hi, had an argument with my boss today about stress distribution in a beam with small 'teeth' sticking out in tension area, bottom of beam: i said there will not be tension stress in the teeth , obviously depending on the dimensions an ratio of width/depth etc, somehow as a gut feeling that is...
  12. NAFTALI-HAKOHEN

    ADDED SLAB AFTER CONSTRUCTION

    hi, im dealing with an apartment, reinforced concrete, that a concrete slab was added in after the original construction, using rebar inserted into perimeter slabs (with epoxy) , see the plans below: now, after 2 years, theres a large crack in the slab, roughly near the joint line of new...
  13. NAFTALI-HAKOHEN

    COLUMN COLUMN STEEL CONNECTION THROUGH EXISTING SLAB

    hi, thanks for that, i hear the issue with the lining up, with regards the concrete drilling, the plate width is 20cm, and i have 4 bolts of diameter 22mm along this side, leaving around 2+ cm space between each bolt, will that leave no concrete between them? im not sure i understand your...
  14. NAFTALI-HAKOHEN

    COLUMN COLUMN STEEL CONNECTION THROUGH EXISTING SLAB

    HI ALL IM DESIGNING A STRUSTURAL REFURB TO AN EXISTING CONCRETE STRUCTURE, WERE SUPPORTING THE EXISTING STRUCTURAL ELEMENTS , BEAMS COLUMNS, WITH STEEL FRAMING, SPECIFICALLY HERE , MY BOSS WANTS A CONTINUITY OF MOMENT THROUGH THE NEW STEEL COLUMNS, THAT ARE POSITIONED ABOVE AND BELOW THE...
  15. NAFTALI-HAKOHEN

    Beam too Near Window?

    Hi. The Wall is 30cm thick concrete I was thinking about a 'column strip' in the wall under the beam as Joel suggested, will this certainly solve the crack issue? Does anyone know how I can calculate the stress concentrations in such a situation without FEM? Dik, the FEM calculation doesn't...
  16. NAFTALI-HAKOHEN

    Beam too Near Window?

    hi i have a design situation with a concrete wall , with a window opening, and a concrete beam that ends quite close to the window, about 10cm horizontally, see diagram: my concern is that the load from the beam going into the wall will cause cracks around the window area - as the load...
  17. NAFTALI-HAKOHEN

    Seismic PGA Values

    hi, a general question, i once heard from a lecturer that Z (MAX PGA VALUES) are increased by the standards as the years go by , AND NO SERIOUS EARTHQUAKE HAS OCCURED... the spring(TECTONIC PLATE) is wound tighter, leading to larger chance of larger earthquake - thus higher Z values i can...
  18. NAFTALI-HAKOHEN

    Queston on Basic Mechanics of Trusses

    Hi thanks all. v insightful tomh could you expand why the second diagonal is less stiff because its carrying the strain of horizontal member, not sure i understand that fully, if horizontal is infinitely stiff how does this change load distribution? thanks
  19. NAFTALI-HAKOHEN

    Queston on Basic Mechanics of Trusses

    am struggling to understand something, in a simple truss with cross bracing like this: why are the axial force compressions in the diagonal braces not equal when the structure is loaded with a unit horizontal force: the horizontal reactions at supports are not equal as i would expect...
  20. NAFTALI-HAKOHEN

    Addition of 8 storeys on a HISTORIC building

    hi, thanks for the guidance, because of the heritage/conservation status of structure it seems we'll have to keep the facades and interiors as close to what they are now, is there a way to reinforce the existing elements (digging out the mud interior and pouring concrete/rebar - inside)...

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