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Recent content by jrmack

  1. jrmack

    Bar Grating as a Diaphragm

    If we are talking about 6 m or 20 feet, welding it down will act as some form of diaphram for a platform. This could stablilze the members supporting the platform (lateral torsional buckling), but beyond that you got to brace things.
  2. jrmack

    Licensing

    I have just paid my $240 to PTC for one year of licensing and upgrades for a year, and have wasted 3 hours of my time to get Mathcad 14 on my new machine. I need licensing codes, and believe me PTC are not making it easy, although I am totally legitimate. I dont know if PTC realizes that their...
  3. jrmack

    Rectangular Plate, large deflections

    My case is simply supported and sliding around the perimeter. The horizontal component required for membrane would come (in my case) from the in plane shear of the plate. Held not fixed gives the largest deflection out of the table on ROARK 5 p 408. Held and riveted is next. Held and fixed...
  4. jrmack

    Rectangular Plate, large deflections

    Tankman650: I am looking at Roark p 408 5th edition. There are a number of edge conditions in the table. What does 'Held, Not Fixed' mean? Shaggy18VW: I tried to get the two tech briefs you mention but cannot find them on the NASA website. Could you please give me a little more direction?
  5. jrmack

    AISC seismic bracing design routine

    Is anyone aware of a routine that will do bracing gusset plate design for connection design (plate thickness, bolts, welds, etc). Ideally it would be Mathcad (that I can modify if I want). Alternatively, it could be a procedure that could be put into Mathcad. Not so ideal, it could be part of...
  6. jrmack

    Can anyone tell me the difference between RESTRAINED & CONSTRAINED?3Q

    Joint Constraints I had difficulty with joint constraints, when I constrained a number of joints together. What happened is, static equilibrium was not satisfied for the model. The lateral loads times the moment arm about the base (a point) did not equal the reaction loads about the same base...
  7. jrmack

    Rectangular Plate, large deflections

    I am looking into stresses and deflections of relatively thin (span/thickness approx 300) rectangular plates (clamped against rotation and somewhat rigid in the plane of the plate along the perimeter of the plate). I read that when the deflection is in the order of the plate thickness (or...
  8. jrmack

    Circular Tie Lap Lenght

    I would use 7.10.4.5 for splicing spiral reinforcement, which I feel is similar. The minimum is 12" or 48db.
  9. jrmack

    Suspended Slab Design

    As far a moment, this is a ACI 318 thing. Dont forget shear. The forklift could give you some problems with shear, especially with tipping, maximum wheel loads, depending on how thin your slab is.
  10. jrmack

    ASTM A 325N BOLTS

    Yes X is better than N, but there is only one A325 bolt. The A325 bolts are the same geometrically for a specific length and diameter, so there is not a special A325 bolt (one that is the N and one that is the X). The bolts attract an N or an X if the threads are included or excluded from the...
  11. jrmack

    Foundation anchor bolts

    For anchor bolts, snug tight should be enough. With concree shrinkage and creep, a bolt tension corresponding to a specified torque would be lost over time.
  12. jrmack

    Connection Idea Needed

    You could weld a 36" C10 c/w clip angles onto the face of the HSS, and bolt connect the stringers to the 36" C10. The HSS would have to be strong enough to handle any unbalanced loads. If this is a 90 degree stair landing, your plate (or clip angle) on one side of the HSS would...
  13. jrmack

    Price of shop details

    I am in Canada also, but also registered as a structural engineer in the US (Washington, Oregon, Hawaii,...) and in Canada from Ontario west. I am working in your industry. You are right that the cost varies substantially, same as yourself, not a simple matter of tonnage. It depends on the...
  14. jrmack

    New Floor Joists

    A 2x8 will not span 12 feet. More like 2x10@16"c/c. A bathroom with tile floors will require two layers of plywood, especially if you use tiles larger than 10". I am not sure why you want to use bolts. The existing 2x6 are not contributing to anything. Just forget that they are...
  15. jrmack

    Ambient Termal stresses in Circular Prestressed Concrete water Tank

    I do not recall any hoop stresses caused by a temperature differential. For the bending moment it is (differential strain caused by temperature/2)*(modulus of elasticity of the concrete)*(section modulus of the concrete). This would be in both directions (horizontal and vertical). This would...
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