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  1. jeffandmike

    Threshold crack width for "damage" to a TPO roof membrane?

    Fair enough. I submitted a "Report" requesting that this thread be moved to the Forensic Engineering forum. That is the closest thing I could find to the topic of the thread. Thanks.
  2. jeffandmike

    Threshold crack width for "damage" to a TPO roof membrane?

    Yeah... I think the issue I had is that if you look at a document like UL 2218A (Outline of Investigation for Impact Resistance of Roofing Systems), for example, the "acceptance criteria" reports that "The roofing system exposed surface shall show no evidence of tearing, fracturing, cracking...
  3. jeffandmike

    Threshold crack width for "damage" to a TPO roof membrane?

    The attached document is a study on the durability of TPO roofing. Page 15 of the document describes how “hailstones larger than 3/4 inch in diameter were among those that impacted” one of the roof membranes (the one in Texas). This roof was sampled at some of the impact locations and examined...
  4. jeffandmike

    Examples of hand written calculations and hand drawn sketches

    Engineering calculations, whether handwritten, on a spreadsheet, or on a commercial computer program, shouldn't significantly obscure the formulas or logic used. When mentoring new EI's, and having them develop their own spreadsheets for some custom calculation, I always have them write out the...
  5. jeffandmike

    Hot Roof Elevation

    This doesn't make sense. Your roof is probably hot, generically speaking, because of heat from the sun... not "because of insufficient insulation or no insulation". In all seriousness, additional detail should be provided. For example... - Is the building entirely enclosed, or is it open to...
  6. jeffandmike

    Allowable size of cope for beams

    Some interesting reading on the subject: http://www.fst.umac.mo/en/staff/documents/fstivp/JSE2003.pdf
  7. jeffandmike

    COHESION VALUE ON STANDARD PENETRATION TEST DATA

    The "Structural engineering other technical topics" forum is not really the correct place for this post. Something closer to correct might have been the "Geotechnical engineering other topics" forum (http://www.eng-tips.com/threadminder.cfm?pid=274).
  8. jeffandmike

    Differential settlement in new connector structure between two existing buildings

    It may be a good idea to think about this in terms of issues other than differential settlement as well. This is kind of what I was getting at in my previous post when I said "for a number of reasons". So... now that we've connected the buildings with a bridge, how good of a job did the...
  9. jeffandmike

    Choosing whether to decrease stud spacing or increase lumber grade for wooden stud walls

    Have to agree with Archie264. 24" on center stud spacing is generally not a good idea. You also begin to run into other issues such as potentially excessive (or even just undesirable) flexibility of the applied finishes when out-of-plane loads are applied. With a single 2x4 stud at 24" on...
  10. jeffandmike

    Foundation for PEMB with Heavy Moment and Uplift Reactions

    Not a lot of time to respond. Hoping this helps a bit:http://www.structuremag.org/?p=342
  11. jeffandmike

    Differential settlement in new connector structure between two existing buildings

    Depending on the specifics of what's being done, I would probably avoid connecting the two buildings altogether (let alone "rigidly"), for a number of reasons, and have the bridge structure be independently supported, both vertically and laterally. I am guessing this won't be too popular with...
  12. jeffandmike

    Mastering structural engineering.

    Your question is fairly broad. There are lot of ways to skin the cat... and you can take this whichever direction you want, so please keep that in mind when reading my response. My advice below also assumes you are working in the US. The first question is... where do you think you want to end...
  13. jeffandmike

    Anchoring Wood Rafters to a Steel Beam (Uplift)

    The "bolted"/attached wood sill plate is the most common solution I've seen in this instance. It allows for relative flexibility with (lateral; along the support) rafter placement in a way that stationary hurricane ties can't. The Simpson "Strong-Drive TB WOOD-TO-STEEL Screw" is a good fastener...
  14. jeffandmike

    Obtaining interviews in the course of forensic engineering investigations

    In the course of investigating my question, I found the following information regarding interviews in forensic engineering investigations (search for terms such as "interview", "eyewitness", etc.). Of course, these don't specify whether these are "under oath" or "on the record". I have more than...
  15. jeffandmike

    Obtaining interviews in the course of forensic engineering investigations

    Nick, Thanks for your response. Of course I have my opinions, but I was hoping not to (potentially) bias the responses, one way or the other (at least not initially), by providing them, or by providing evidence supporting one opinion over others. I also have a genuine desire to hear what...
  16. jeffandmike

    Obtaining interviews in the course of forensic engineering investigations

    Everyone, I've been practicing as a forensic engineering expert witness largely related to residential buildings for about ten years. I was hoping to obtain some level of consensus on how you felt about the role of interviews (i.e., with owners, tenants, etc.) in the course of performing...
  17. jeffandmike

    Wood Gable Roof Diaphragm

    Jerehmy, As far as I know, there is nothing in the code that typically requires "top" ventilation, as you refer to it. "Cross ventilation" is required, but this can be accomplished by having ventilation at the eaves on either side of the roof, as I previously described. If 40% - 50% of the...
  18. jeffandmike

    Wood Gable Roof Diaphragm

    The ridge vent seems to be the primary (though not necessarily the only) problem in this discussion. Why not omit it, and get your ventilation elsewhere... like down at the eave? Aside from the diaphragm issues discussed above, ridge vents eventually leak at the poorly (non-existent) sealed...
  19. jeffandmike

    "Structural damage" - "[ANSI] building standards for residential construction"?

    a2mfk, Thanks for your post. Not helpful to my original question, but interesting nonetheless. Re: the current definition(s) of "structural damage" in Florida... they are garbage. Re: "sinkhole activity" being subjective... you bet it is. I had a conversation with a highly respected geologist...
  20. jeffandmike

    Use of SE stamp

    How did the owner become aware of the differences in the design/construction requirements of a 75 mph building versus a 90 mph building? As engineers, sometimes we can be our own worst enemies by being "too truthful" and offer explanation where none was requested, where none was necessary, or...
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