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Recent content by TrussBridgeboy

  1. TrussBridgeboy

    I've been asked to design a tempora

    Thanks everyone for your replies. I had searched the 'net for a person or company to do such a structure (the suspension cables) but didn't have much success. I believe the pipe is now along a bridge that's being rebuilt over a creek, thus the temporary nature. We are a competitor to Bridge...
  2. TrussBridgeboy

    I've been asked to design a tempora

    I've been asked to design a temporary bridge for a 2" waterline to span 145'. Rather than do such a large structure for such a small thing, I was thinking a suspension cable set might be more appropriate. Does anyone know who does that sort of thing? I've seen those types of structures done...
  3. TrussBridgeboy

    Two Point Loads on Stair Treads

    I once worked for an FRP manufacturer and designed structures with FRP shapes. It is customary to include shear effects in deflection calcs. In the steel joist business, I've seen people calculate the Ix of the chords, use that as an equivalent beam, and then add about 20% to the deflection to...
  4. TrussBridgeboy

    Pedestrian truss "pony truss"

    One other thought since you all brought up K-factors - We generally use a K factor of 2.0 for the truss vertical in the out of plane direction unless you have a good reason to use something less like 1.5. You can use a K=0.8 or 0.85 for the in plane K-factor for the truss verticals.
  5. TrussBridgeboy

    Pedestrian truss "pony truss"

    The code statement you referenced about framing into the bottom chord was placed there by yours truly (via appropriate correspondence with the AASHTO committees). The problem with framing the floorbeam into the bottom chord is that the chord will "ovalize", as shown in KOOTK's post and referred...
  6. TrussBridgeboy

    Concrete Encased Vierendeel Truss Girder

    It sounds like a fun experimental project for an engineer to me. If it's for a paying customer I wouldn't touch it with a 10' pole. Unless you know where it's been done before successfully, then who knows what will happen, as many posters have speculated. Five feet is very shallow...
  7. TrussBridgeboy

    Out of plane stability of truss chord supported by 'wind-posts'

    See the book "Guide to Stability Design Criteria" by T Galambos, particularly chapter 15. What you have is a top chord synonymous to a column buckling restrained by "elastic lateral restraints" - springs. The guide is intended for pony truss bridge design but you may find enough info there to...
  8. TrussBridgeboy

    Humen Bridge

    I wonder if the vortex on the towers have any contribution to the problem. It might not be all in the deck.
  9. TrussBridgeboy

    Uniform & Non Uniform Flow Types

    Based on your own definitions, then you've answered your own question - non-uniform. Is your pipe "full" or an open channel type flow as in a drain pipe? It's been a long time since I've broached the subject but hydraulic jump comes to mind of your situation if it's open channel type flow.
  10. TrussBridgeboy

    Fracture Critical Bridge

    There have been several continuing education seminars on the topic from AISC/NSBA. I haven't checked but you might find them on the AISC website. It has been a hot topic at the last few NASCC (North Am. Steel Const. Conferences) too. "Fracture Critical" is often confused with "non-redundant"...
  11. TrussBridgeboy

    FEMA flood zone

    The property is roughly 200' wide by 1500' long. It has a small creek in a very deep ditch down the long side. It's all along a RR track so it's more like a drainage ditch than a creek. The RR is several feet below and along the long edge of my property. I just thought it very odd that the...
  12. TrussBridgeboy

    FEMA flood zone

    Thanks for the reply. No construction contemplated, I was investigating using it as collateral for a loan and the bank insisted I get flood insurance, when it wasn't needed way back when I used a mortgage to buy it. I'd like to get it "corrected", if possible. It may affect future sale...
  13. TrussBridgeboy

    Reaction loads at the Support of an overlapping structure

    Excellent question. I'm fascinated by how many different approaches there are to the same problem. Not saying any are correct or incorrect, just different. It's enough to drive lawyers nuts. Here's mine, which I'll admit may have a math mistake, no time to check thoroughly. I'm somewhat...
  14. TrussBridgeboy

    Engineer wanted splice on middle post

    There are so many assumptions in loading, soil capacity, material strengths, factors of safety, and the like that a slight difference in actual vs. theoretical should be fine. Sounds like the engineer in this case (and I’ve run across my share of Dr. dot the I and cross the T’s) might be “good”...
  15. TrussBridgeboy

    FEMA flood zone

    Anyone have experience with changing a FEMA flood zone? I own property that FEMA changed partially into a flood zone in 2011. The problem is they put the high end of the property (about 10 acres) in the flood zone while the end 7' lower is not in the flood zone. The property has never flooded...
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