Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations MintJulep on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  1. ElliottJames

    Wind loads - servicaebility and ultimate

    Wow. I have a different view of what Ultimate wind loads are. It has nothing to do with safety. Using 1.2D + 1.0W + L combo for example, note the lack of load factors except 1.2 for dead load. When designing to this load combo, the structure is at the yield point. It is on the knife's edge of...
  2. ElliottJames

    Frustrating, persistent misconceptions that pervade your office

    "Tack welding of rebar shall always be prohibited." -- Never mind that the rebar details in the footing are driven by temp and shrinkage, not ultimate or service loads, and whatever small strength that is lost at the rebar connections are insignificant and immaterial.
  3. ElliottJames

    Relocating an Existing Lattice Tower

    Even though this is not a telecomm tower I would use the TIA-222 standard. The equations, methods, etc. are all highly refined for just this application, a lattice tower made out of angle iron. Wind loading, and the resulting P-delta, are important for a 60-foot standalone tower. Don't forget...
  4. ElliottJames

    Service Wind Speed Drift ASCE 7-16 Load Combination

    Speaking of 7-16 wind speeds, I'm somewhat amazed at the drop in basic design speeds on the west coast. Using Fresno, Calif. as an example: 7-10: Cat II 110 mph 1.2D + 1.0W 7-16: Cat II 94 mph 1.2D + 1.0W That's about a 27% drop in design q.
  5. ElliottJames

    Early / Partial Loading on Recently Placed Concrete Foundations

    Drilled and epoxied anchors into new concrete? Not cast-in-place?
  6. ElliottJames

    AASHTO - Vortex Shedding Analysis Method

    I really don't see how vortex shedding would be a problem here. Shedding won't occur around the tower as a whole because, like WARose said, the solidity is far too low. Shedding can develop as the air flows around each leg, however. But the entire length of the leg can't develop a harmonic...
  7. ElliottJames

    Do We Know what "Renewable Energy" means?

    zdas04: "Ten climate related disasters? in 2015" What where they? You're right, I should have written "ten weather related disasters" not climate related disasters. The list of events is listed here: http://www.ncdc.noaa.gov/billions/events While it is true that no weather event is directly...
  8. ElliottJames

    Do We Know what "Renewable Energy" means?

    Looking at the big picture, the O.P. is correct, the phrase "renewable energy" is a poorly defined and sloppy term. Technically there is no such thing as renewable energy because the arrow of entropy only points one way. Even solar power is not renewable -- once a pair of H nuclei fuse to form...
  9. ElliottJames

    Slender steel column: Linear FEA vs Moment Magnification

    @bookowski wrote: "Run one model with a single element and another with divided elements. If it's linear you will get identical results, if it's performing p-d you won't." Of course, thank you for the suggestion. Set up a simple model of a 20-foot tall HSS 2.50x0.125 A36 steel tube. 100 lbs...
  10. ElliottJames

    Slender steel column: Linear FEA vs Moment Magnification

    @JoshPlum: It's a linear FEA program. And maybe this gets at the heart of my thinking: that linearity (Hooke's Law) holds for each segment. Now as the column is broken up into an increasing number of segments, the accumulated nodal deflections and strains act as a limit function and approach the...
  11. ElliottJames

    Slender steel column: Linear FEA vs Moment Magnification

    Apologies if this seems like an elementary question, but I haven't been able to confirm the answer searching here or elsewhere. Given: a slender steel column with a downward vertical force P at the top and a sideways force P, also at the top. Assume the material is in the elastic region and...
  12. ElliottJames

    best tower analysis software

    Bah, tower software is for wimps. Real engineers model their towers with a generic FEA program from scratch. ;-) I have done this. The disadvantage is that it can get tedious to post-process the FEA output vs. factored material strengths. The advantage is you really get to know TIA-222-G and...
  13. ElliottJames

    Pullout strength formula [D-15/ACI318-11]

    It appears to be a different mode of failure? Bearing strength failure is due to cracking, while anchor bolt pullout failure involves localized crushing around the bolt head (source: ACI D commentary).
  14. ElliottJames

    CFT: Moment of Inertia?

    @ PRM06: Thanks, that's exactly what I was looking for. I'll take your advice and add it to my bookshelf.
  15. ElliottJames

    CFT: Moment of Inertia?

    @ Agent666: thanks, I understand the concept of effective stiffness. This document doesn't provide what I'm looking for, which is a general geometric equation for the moment of inertia of a chordal area and of a chordal portion of a hollow tube.
  16. ElliottJames

    CFT: Moment of Inertia?

    I'm working on a design that includes a concrete-filled steel tube. Might anyone have equations handy for the moments of inertia when the neutral axis does not go through the center (see attached diagram)? Referring to the diagram, I'm looking for the MoI of the concrete in compression (area...
  17. ElliottJames

    ASD Footing with an LRFD Structure

    Thank all of you very much for your responses. Enhineyero your explanation was clear and helpful -- and you're right, using your suggested method keeps the footing size reasonable.
  18. ElliottJames

    ASD Footing with an LRFD Structure

    Older PE here. I admit I'm rusty and I'm doing my best to get up to current methods and standards. Project is a self-supported lattice tower with a simple gravity mass footing. Tower mfr. shared some sample calcs with me. Calcs show LRFD basis for wind force and sizing the lattice members...

Part and Inventory Search

Back
Top