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  1. idecharlotte

    Collector requirements in rigid wood diaphragms

    So out of curiosity let's say you have a 24' deep by 33' wide garage with only three 9' openings in the 33' side (18" lugs.) By the tributary method you would need steel moment frames around the garage openings. By a rigid analysis you would likely need nothing. I don't think detailing out a...
  2. idecharlotte

    Multi-wythe brick wall support during lintel replacement

    I generally use needle beams to shore masonry. You just have to space them a little closer for older masonry. www.idecharlotte.com
  3. idecharlotte

    Collector requirements in rigid wood diaphragms

    MotorCity, Flexible diaphragms probably make more sense for diagonal board sheathing but not for modern OSB such as Advantek, which can be twice as rigid as conventional plywood. But even with plywood diaphragms, the math usually indicates that it is rigid or semi-rigid and hardly ever flexible...
  4. idecharlotte

    Collector requirements in rigid wood diaphragms

    ^In my experience the difference can be thousands of dollars on an average large and complicated custom home, and when you are competing with engineers that ignore LFRS almost completely because of lack of understanding, then it makes it tough to compete in an already very cost sensitive...
  5. idecharlotte

    Collector requirements in rigid wood diaphragms

    Despite the popular consensus to design wood diagrams as flexible, in most cases with new construction they are almost always rigid. With irregular shaped buildings the most common method of handling diaphragm horizontal offsets is by using collectors with drag strut connectors to the shear...
  6. idecharlotte

    Justifying Shear Wall at upper level of Condo - help please!

    The window only effects the shear wall at the upper story, not any of the stories below. You can treat it as a perforated shear wall if you wanted more favorable results. Based on your sketch, assuming the window opening is reasonable (at least 4 ft. of wall on each side), I doubt you will have...
  7. idecharlotte

    Adding a Timber POST to a steel POST = OK?

    Not sure why the beam can't remain in place and transfer the wall load to the beam in a more creative way, but a sketch would help. www.idecharlotte.com
  8. idecharlotte

    Truss Metal Plate Failure

    I reinspected the truss plates again. They definitely failed by teeth pull-out. The wood was in good condition, dry, with no signs of roof leaks. The roof had proper ventilation with ridge and soffit vents. Several other plates on some of the diagonal members have begun to experience plate...
  9. idecharlotte

    Truss Metal Plate Failure

    Timber was in good condition, plates were fully engaged. No signs of roof leaks or rot. www.idecharlotte.com
  10. idecharlotte

    Truss Metal Plate Failure

    That snow load really doesn't matter since the design Live load is always higher in Charlotte. So even if I was off on my estimated 7 to 10 PCF density of snow, it is nowhere near the 20psf live load the truss is supposed to handle. Besides, there really wasn't a drift issue where the failure...
  11. idecharlotte

    Truss Metal Plate Failure

    This past winter Charlotte had a whopper snow storm with almost 6 whole inches of accumulation. I am now looking at my second roof truss failure as a result. Both situations are identical. Churches with scissor trusses spanning 46 feet, both built in the mid-90s. The truss company who did both...
  12. idecharlotte

    Waterproofing Exterior Suspended Slab on Steel Framing

    I've specified a silicate sealant before such as Concrete Treat for situations like yours to eliminate the need for a topping slab and membrane. It works great. I probably wouldn't use it on an slab without a roof with heated space below but for an elevated garage, or slab without heated space...
  13. idecharlotte

    Southern Pine design values and the IBC

    Most framers I've talked with hate using SYP and the few times I framed houses, it was a PITA to work with because it was twisted, knotted, excessively crowned. We never called it out before due to these reasons. We've always used Spruce. The design value changes pretty much reinforce this...
  14. idecharlotte

    Structural system selection

    Cross Laminated Timbers FTW.:)Beats them all. www.idecharlotte.com
  15. idecharlotte

    East Coast Connection Design

    I'm dealing with this right now. The owner wanted the least expensive design drawings possible for a somewhat complicated and unique structure. I told him he was going to need tons of connection details for this job. So I gave him a price to do the job without connection detailing and with...
  16. idecharlotte

    Reinforcement of existing steel joist.

    Use Post-tensioned cables. I've used them before on bar joists, concrete and glu-lams to gain strength. www.idecharlotte.com
  17. idecharlotte

    Bending stress of plywood gusset plates

    I've always had difficulty finding the allowable bending stress of plywood and OSB in an application where it is to be used as a gusset plate. I can find stresses for its normal floor application, but I wouldn't assume them to be the same for orientation in a built up beam situation. I've...
  18. idecharlotte

    Earth Sheltered Roof Structure Unofficial Poll

    I'm not sure of the geometry of the structure but I would consider post-tensioned P.I.P. concrete roof slab for those spans. That way, you just have to drive concrete trucks up and not deal with hauling long steel members or using a crane. www.idecharlotte.com
  19. idecharlotte

    Intersecting Double Ridge & Valley Beam Connections

    We brace all hip/valley/ridge intersections with a double 2x6 'T' down to a beam or bearing wall. On top of the brace is a flat 2x10 or 2x12 piece that catches all the members. In the event that you cannot brace, the"wedge" action creates a thrust on the walls that you would need to design for...
  20. idecharlotte

    Designing a boathouse

    I found this after further looking: P = 8.15 (DWT)^0.5*V Either way, if I assume a 1 ton boat hitting at 1 ft./sec I get at least 8.15 kips of force. Seems pretty high to me. www.idecharlotte.com
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