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  1. sekwahrovert

    Base plate thickness

    Don't forget to consider that the horizontal load creating the bending moment may be applied in a diagonal direction. If applicable, this load direction will almost certainly control the design of the anchors and base plate and may also control the design of the footing if the footing is...
  2. sekwahrovert

    Suspended pendulum-like structure

    JStephen, Thank you for the reference. Equation 15.4-6 seems overly complex for what seems to be a simple system. For simple pendulums, T = 2*pi*sqrt(L/g). I would think a similar equation would exist for my system that doesn't require forces and deflections as input. The assumption of...
  3. sekwahrovert

    Suspended pendulum-like structure

    Thanks for responding, WARose, but I don't agree. ASCE 7-10 Sections 13.5.1 and 13.6.1 address architectural, mechanical, and electrical components "which are supported by chains or otherwise suspended from the structure." Further reading in these sections makes it pretty clear (at least to...
  4. sekwahrovert

    Suspended pendulum-like structure

    Consider the design of a suspended structure idealized in the attached sketch. The suspended structure is fairly rigid and suspended by 2 cables (or 4 in a 2x2 grid). How would one determine the natural period of such a system? Is it a simple formula containing the dimensions A, B, and/or C...
  5. sekwahrovert

    do i need to specify cold formed steel vendor?

    No, but you need to specify more than just the depth. You should specify the depth, width, thickness, and material grade. Others may add to this list.
  6. sekwahrovert

    Wood Truss - Improving strength of Nailed Member Joints

    I agree with those on this forum who have expressed concern with the overall strength of the existing trusses. The potential problem is not with the proposed addition of a ceiling and insulation--that won't make things much worse than they already are. I suspect that the slippery metal roof...
  7. sekwahrovert

    Guy Anchor Detail

    I have designed a guy anchor (reinforced concrete block) and some questions have been raised about the detail I provided. Please see attached and provide any feedback if anything jumps out at you. Thanks in advance...
  8. sekwahrovert

    Self Support Tower - Truss Leg Modification - TNX

    I agree with msquared's advice. The TNX expert that I think he is referring to is: Peter Chojnacki Tower Numerics Inc. peterc@towernx.com www.towernx.com Phone: 1-781-862-0966 Toll-Free: 1-855-TOWERNX (US and Canada) Fax: 1-781-538-6463
  9. sekwahrovert

    Screw Pier Variation

    I agree with Once20036. This is a contractual question.
  10. sekwahrovert

    Contract Documents

    Our typical contracts have all been reviewed by our liability insurance provider. They and the attorneys they employ have been an excellent resource for us at no additional charge.
  11. sekwahrovert

    Strings on Pole

    Perhaps I'm stating the obvious, but the wind loading from the light string will be partially in the direction of wind and partially perpendicular to the direction of the wind. The perpendicular portion of the load will be sensitive to the sag in the line. Perhaps you could determine the...
  12. sekwahrovert

    Effective Length of cross braces

    If both braces are in compression, I would not consider them able to brace each other. I don't know what you're designing, but If it's anything like the towers that we design where I work, it's hard to imagine a controlling load combination in which both braces would be in compression.
  13. sekwahrovert

    Safety factors for compression

    You're looking at the design aids rather than the specification section of the AISC manual. You can confirm the phi factor for steel compression members = 0.9 in section E1 (page 16.1-32). The phi factor for composite steel & concrete compression members is given as 0.75 in sections I2.1b...
  14. sekwahrovert

    Basic truss chord splice question

    You need to transfer 100 k from the left chord to the left bolt. Then 100 k from the left bolt to the splice plate(s). Then 100 k from the splice plate(s) to the right bolt. Then 100 k from the right bolt to the right chord. I think a free body diagram will easily settle the question. Is it...
  15. sekwahrovert

    Basic truss chord splice question

    Using RISA, I don't know how you determine the force at a node, but you can determine the force in a member. Look at the force near the spliced end of the chord. That is the force that needs to be transferred into the bolts and plates that you will design to form the splice.
  16. sekwahrovert

    Calculating loads on oak beam for ditch crossing

    You might consider something like the temporary crossing structure shown here: Bridge Video
  17. sekwahrovert

    Wind Pressure Minimum requirements

    All pressures listed in ASCE 7-05 and ASCE 7-10, including those in the tables for simplified methods and the minimum pressures you mentioned, are 1.0W. You should modify these pressures according to applicable load combinations. You are correct that 16 psf is ultimate because the LRFD load...
  18. sekwahrovert

    RISAFoundation

    Yes. You have recreate all of your load combinations, but I've never had any problems with integration.
  19. sekwahrovert

    Pipe to plate weld selection

    Thanks for all of the input. Kootk, I understand what you mean about bending moments in the plate being transferred through the welds. However, I'm not sure how the option 1 is more effective at transferring the bending stress. As you say, the lever arm is very small in option 2, but it is...
  20. sekwahrovert

    Pipe to plate weld selection

    I frequently design monopole-type structures with pipe-to-pipe splices subject to large reversible shear and moment loads from wind. I've attached a sketch of a typical connection with 2 options for the weld of the plate to the pipe. I'm looking for opinions: which is the better weld for this...

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