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  1. Dowels93

    Partial Collapse, London, Ontario

    Update to the story: At least 5 taken to hospital, 1 without vitals, and likely 2 more trapped. Fire rescue teams are on site, with heavy rescue also on the way from Toronto. There is also a video of inside the collapse at https://twitter.com/andrewjwgraham/status/1337477805899132933
  2. Dowels93

    Simple Beam Check with ASD vs LRFD

    To determine what the beam can "actually take", you'd have to calculate the beam strength without any resistance/safety factors (i.e. phi=omega=1), which should give the same result regardless of method. ASD and LRFD use different loads as well; ASD are not factored, LRFD are factored. In the...
  3. Dowels93

    Moment of Inertia and Cross-Sectional Area

    You may use either table, but just be consistent. Table 6.6.3.1.1(a) is for use where you don't want/need to be extremely accurate with your stiffness reduction or don't know your load levels yet, and you apply the factors to everything equally. This essentially assumes all elements are losing...
  4. Dowels93

    Moment of Inertia and Cross-Sectional Area

    Factored load level refers to an ultimate limit state (ULS) (i.e. safety critical, if it exceeds this it may fail). Unfactored loads, also sometimes called service loads, refer to a serviceability limit state (SLS), which is not safety critical (i.e. how do people feel using this building...
  5. Dowels93

    Snow Drift Seismic Mass

    The Ontario Building Code (OBC) also requires "25% of the design snow load specified in Subsection 4.1.6" to be included, which technically includes snow drifts. That being said, I would - and typically do - take a snow load for seismic that accounts for drifts through rounding up in broader...
  6. Dowels93

    Roof diaphragm design

    Reducing the size of your diaphgrams may also help reduce the demand in the diaphragm itself. You could do that by providing more supporting lines (walls/frames) or using collectors in clever ways (highly dependent on geometry to be effective). If your diaphragm is wind governed and partially...
  7. Dowels93

    ETABS Shear Wall Design EC

    I might have read this wrong years ago, but I believe ETABS: 1) plots an interaction diagram (P vs M) for the wall 2) plots the various loading points 3) draws lines from the origin through each point to find where the line intersects with the interaction diagram envelope (interpolated between...
  8. Dowels93

    dv for 2-way slab punching shear check at column

    I can't find the original source with a quick look, but MacGregor & Bartlett's "Reinforced Concrete Mechanics and Design" (1st Can. Ed.) states that ACI-ASCE based their clause on Johannes Moe's work, but used a d/2 simplification where d was the average effective depth of the slab. Johannes...
  9. Dowels93

    Hi sirs. I am designing an eccentri

    I would suggest designing this by hand (using the distributions shown above) rather than using SAFE to design it for you. This will enable you to allow uplift to occur on one side if necessary, so long as you then use a triangular soil load distribution to determine your peak pressure. It will...
  10. Dowels93

    Hi sirs. I am designing an eccentri

    BAretired is correct, 3c is the length of the triangle. The attachment has it labelled correctly.
  11. Dowels93

    Hi sirs. I am designing an eccentri

    When the footing goes into uplift, you cannot rely on that soil any more, and the assumed soil load distribution becomes a triangle (as shown by the bottom of Ron's figure) and you cannot use the classic P/A +- M/S to find the peak pressure. The situation is still ok to design, but you just have...
  12. Dowels93

    Ledge beam with no reinforcing in the ledge

    Just looking at that detail makes me uncomfortable. I like the idea of drilling into the beam and anchoring with adhesive, and the anchorage on the right hand side would probably require a plate/angle as skeletron said. I'd argue for extending the reinforcement past the second tie by the...
  13. Dowels93

    Structural Concrete Slab Reinforcement

    Is it a composite or non-composite deck? Are you also planning on using the concrete in a composite system with the steel beams (unrelated to whether it is a composite deck)? What other loads might be added (i.e. shelving/racking if it's a garage, not just a driveway)? The slab thickness will be...
  14. Dowels93

    Structural Concrete Slab Reinforcement

    My recommendation is to look at hiring a local structural engineer who can evaluate the loads, load path, and reinforcement as necessary. It seems beyond the typical information you'd get from an online forum.
  15. Dowels93

    Residential Slab on Grade Footing

    As KootK & jayrod12 said, it's common and hasn't failed yet... but that's probably more to small loads, conservative bearing values, and failures causing settlement rather than catastrophic failures. To quantify though: These footings are tied back to resist some rotation, so you could probably...
  16. Dowels93

    Residential Slab on Grade Footing

    Footings in particular are prone to layout inaccuracy, so a footing failing with even a small eccentricity is of concern since you have a good probability of seeing those eccentricities just from construction. I would personally consider the eccentricity unless the footing is tied into the slab...
  17. Dowels93

    Corner Zone Loading at Small Outside Corners

    I agree with DaveAtkins that corner loads should only be applied at corners of the overall structure, not every jog in the structure. My understanding of corner zones is that the additional wind pressures are present due to the stream created as the wind blows against the building and flows...

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