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Recent content by BridgeSmith

  1. BridgeSmith

    How to install tie rods to counter roof thrust in a barn with a central post obstruction?

    Why try to attach to the masonry to resist the thrust of the rafters? Why not just attach directly to those timber rafters? I'd look at adding anchor plates to both sides of those timbers (through bolted at the ends of the timber rafters) to attach rods or cables on each side of the post...
  2. BridgeSmith

    Conversation starter: How heavily do you rely on computational tools?

    #3 - Maybe 3% #4 - 85 -90% #5 - 10% The 10% hand calcs is usually in the first iteration of design for a component of a different type, which is them automated in Excel. Occasionally, there's a one-off design or review calculation I'll do by hand, also.
  3. BridgeSmith

    W36x925

    Maybe, but so would a deeper girder that weighs 1/4 as much.
  4. BridgeSmith

    W36x925

    Yeah, I think my manual is about 30 years old (LRFD 2nd Edition - silver). I put in a $100 budget request for for a newer one (hey, they asked). Looks like I can get a 14th Edition for that, anyway. By the time it gets approved, I might be able to get a 15th Ed.
  5. BridgeSmith

    W36x925

    Where are the reactions shown? It looks like to me the length is 45 ft ("36x925x45"). Still a very inefficient use of steel, unless the available depth has a very hard limit, which would indicate an architect with more arrogance than brains was probably involved.
  6. BridgeSmith

    Single Span Bridge Seismic Requirement per CHBDC

    The commentary is in line with my understanding of the reasons for the exclusion of single span girder bridges. For the type of bridges excluded, the deck is strong and stiff, and provides substantial lateral bracing for the girders. This may not be the case for truss superstructures, which may...
  7. BridgeSmith

    W36x925

    That size isn't even in my AISC Steel Manual. 36x848 is the largest.
  8. BridgeSmith

    Steel Beam size vs Wood

    Last time I checked the NDS, the only other common species I saw with allowable stresses as high as Douglas Fir is SYP (Southern Yellow Pine)
  9. BridgeSmith

    Single Span Bridge Seismic Requirement per CHBDC

    I think the article means what it says. Unless your trusses are actually open web girders, you should do the analysis for seismic loads as specified. Girders are fairly robust for lateral loads; most truss types, not so much. The trusses may be fine for the transverse inertial forces due to...
  10. BridgeSmith

    Deep piled footing recomendation

    Our driven piles are steel H-piles, and nearly always driven to refusal (end bearing in rock).
  11. BridgeSmith

    Lateral Loaded Pile with Pile Cap & Slab-on-ground

    I was specifically addressing the case where the concrete component is supported by piles. For a slab on grade not supported on a deep foundation component, you could use the friction, although you'd only get to count the minimum permanent load on the slab, which typically wouldn't provide much...
  12. BridgeSmith

    Lateral Loaded Pile with Pile Cap & Slab-on-ground

    We typically don't include friction under a pile cap, since we consider any bearing load on the soil to be questionable. Passive resistance of the soil against the sides of the footing is sometimes used to reduce the lateral load on the piles, if the movement needed for mobilization doesn't...
  13. BridgeSmith

    Deep piled footing recomendation

    We had one case where a historic building with a stacked stone foundation was near the bridge site. We used drilled shafts (drilled caissons) for that bridge. I don't know of any projects where we weren't allowed to do driven steel piles due to the noise. That doesn't mean there weren't, just...
  14. BridgeSmith

    Deep piled footing recomendation

    I keep forgetting that "piles" can refer to drilled or augered concrete shafts, not just driven piles. We haven't used CFA for any of our foundations, but we may be using all larger shafts than what you're considering. 3' (1m) is about the smallest we use. For those and larger, we use...
  15. BridgeSmith

    Deep piled footing recomendation

    For bridge substructures, we wouldn't typically consider drilling holes and encasing the piles unless we were anticipating needing to drive piles more than 35 meters. Drilling is 10x more expensive per foot (or meter) than driving piles. However, the economics in your location may be different...
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