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  • Users: JKW05
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  1. JKW05

    CP60 Coating for Cold Formed Framing

    I have specified a G60 coating for cold formed steel framing at a wastewater treatment plant. The contractor has submitted product data for material with a "CP60 coating" This designation apparently covers galvanized (G60), galvanneal (A60), galvalume (AZ50), and galfan (GF30). My spec...
  2. JKW05

    Lag Screw length

    Good morning. I posted this on the Materials Engineering forum and didn't get many bites. I'm hoping it's O.K. to try to direct traffic to it from here. http://www.eng-tips.com/viewthread.cfm?qid=455116 JKW
  3. JKW05

    Maximum Lag Screw Size Penetrating into 2x Main Member

    Say we're fastening a nominal 2x member to another nominal 2x member with lag screws. 2015 NDS 12.1.4.6: "The minimum length of lag screw penetration, pmin, not including the length of the tapered tip, E, of the lag screw into the main member of single shear connections ... shall be 4D." If a...
  4. JKW05

    Steel Portal Frame Frequency

    Thanks Bones! Mode 1 = 118 HZ is certainly close to the 111 Hz from my original post. JKW
  5. JKW05

    Steel Portal Frame Frequency

    The frame is used to test safety harnesses. The standard specifies the minimum natural frequency of the drop test structure. Don't know that I can buy into it meaning anything other than the structure.... Thanks for your input. JKW
  6. JKW05

    Steel Portal Frame Frequency

    The referenced requirement from the standard is quoted in the 4th post of this thread. "I've always taken the simplification of 18/sqrt(9.81)as shown here for a uniformly distributed mass & stiffness case:-" Where did the 9.81 come from? Did you mean 18/sqrt(delta)? The first two forms...
  7. JKW05

    Steel Portal Frame Frequency

    I agree that is likely the intent, but why not 100 or 150 .....? (rhetorical question).
  8. JKW05

    Steel Portal Frame Frequency

    The impact load is 200 to 300 pounds. The 200 Hz requirement is from the ANSI Z359.7 standard referenced above, although I do not know what that requirement is based on.
  9. JKW05

    Steel Portal Frame Frequency

    Thanks for your responses guys. SocklessJ, you indicate that my analysis is based on load, not mass. But all 3 of the derivations I posted use the basic equation of f=[1/(2 x pi)] x (k/m)^0.5 where m=W/g. Except for the discrepancy between the 0.18 and 0.16, this is also consistent with what...
  10. JKW05

    Steel Portal Frame Frequency

    I had modeled the frame in an analysis program with the following results: Beam Deflection: Model = 0.00048" Hand Calc = 0.000394" (simple beam = 5wL^4/384EI) The frame analysis program includes shear deformation which I have calculated to be 0.000094" Beam Deflection: Model =...
  11. JKW05

    Steel Portal Frame Frequency

    patswfc: We have discussed the axial shortening condition in our office. I agree the deformation is already in place, especially since it is an existing frame. But the question to us then becomes do (can) we also ignore the beam self-weight deflection which has also already occurred. The...
  12. JKW05

    Steel Portal Frame Frequency

    ANSI Z359.7 "Qualification and Verification Testing of Fall Protection Products", Section 4.1.1: "The required minimum natural frequency of the drop test structure shall be 200 Hz when measured along the vertical axis through the point of the test anchorage or anchorage connector to which the...
  13. JKW05

    Steel Portal Frame Frequency

    I have attached a sketch and calculations for a simple frame which will have a very small impact load applied downward at the mid-span of the beam. The required minimum natural frequency of the structure measured along the vertical axis at the mid-span of the beam is 200 Hz. From the attached...
  14. JKW05

    Lateral Load Level Definition and Height

    Thanks Koot!
  15. JKW05

    Lateral Load Level Definition and Height

    ASCE 7 defines hi as the height to Level i, with "i" being the buiding level and i=1 being the first level above the base. The attached file shows three typical building sections (I hope I attached it correctly). Figure A shows an illustration taken from a masonry text book used in an example...
  16. JKW05

    Fiberglass exposed to Ozone

    I have been looking for information regarding the suitability of using fiberglass gratings/railings in a water treatment plant with ozone concentration less than 1 ppm in the air. It seems that understanding the ozone concentration in the information I have been able to find is elusive, and...
  17. JKW05

    Monopole base design (follow-up)

    ...Also, page 57, the fourth term in the brackets has "r^2"; page 60 uses "r^4". I believe this should be "r^4" (??)
  18. JKW05

    Monopole base design (follow-up)

    thread507-340309 This is a follow-up to a post from last March concerning Daniel Horn's technical manual on monopole base designs. On page 56, y1 is define using Ac in the denominator. On page 60, the value for A1 is pluged into the equation. I believe the equation on page 56 should use A1...
  19. JKW05

    New roof sheathing over old?

    Thanks for your responses. Didn't feel real good about covering it up, but just wanted some other opinions.
  20. JKW05

    New roof sheathing over old?

    50 year-old house with 3/8" plywood sheathing on trusses spaced at 24". Roof shingles are to be replaced. Attic ventilation comprises of a poorly installed ridge vent with no soffit vents. Walking on the roof feels very "spongy". There does not appear to be any roof leaks but, from poking at...

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