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  1. TpaRAF

    Removing existing timber piles

    In Florida we have a widget called a pile nibbler, that basically shears concete piling by crushing. The problem here would be excavating down enough to get the hydraulic shears into place. Why couldn't you excavate down to the point a chain saw could be used to lop away the piling? Two...
  2. TpaRAF

    AASHTO LRFD bridge design Spec 4th --> SI Version

    The various formulae and materials data will also be in SI. The exam is probably in english UOM. So ... the answers you get will be near but not exact, due to rounding of coefficients, etc. When I sat for the exam, I used my AASHTO code to work out a glulam problem. I needed the manual just...
  3. TpaRAF

    Structural Steel Shapes

    Neat! how did you get the file attachment? Thanks, RAF
  4. TpaRAF

    Bearing Capacity/Pressure of Existing Asphalt

    If this is for building design, the lateral wind loading forces tend to be much larger than the gravity loads. You'll get quite an uplift load on the windward size (and slack cables on the leeward side). Regarding the bearing capacity, the prepared wearing + base courses should be much denser...
  5. TpaRAF

    Foundations for Large Sign

    Arrgh -- 6ft => 2m RAF
  6. TpaRAF

    Foundations for Large Sign

    On Florida DOT projects, we have gone almost exclusively with drilled shafts (caissons). Given the overturning forces, I would think socketing the caisson into the rock would give you a good design. You mentioned weathered rock, so the socket would need to be in competent material. Is this a...
  7. TpaRAF

    Filler for structural bolt holes

    Thanks for the comments. Minerk -- This particular jurisdiction of the DOT has had bad experience with field welding, and will generally reject repair plans calling for it. The real issue is having the government low bidder using the lowest paid welders he can get. Some of this work is...
  8. TpaRAF

    Welding vs Bending

    Hi, Wolfman : Why bend this or weld this? It seems like angle iron 5 x 5 x 3/4in would meet your needs. Is the material grade exotic? Regards, RAF
  9. TpaRAF

    Pipe Coupling Strength

    Hi, Wolfman: Where is the coupler at? The rail/piost junctions or the middle of the (horizontal) railing? RAF
  10. TpaRAF

    Filler for structural bolt holes

    Thanks for the suggestions from everyone. "Minerk" is correct that the scab plates extend well beyond the damaged sections, to where solid connections are made (normal practice for this type of repair). "Prost" summarizes the key issue - the voids are too large for any fasteners. Given the...
  11. TpaRAF

    Filler for structural bolt holes

    Thanks to all for the comments and input. One aspect I must not have made clear is these holes (from corrosion of the beam flanges) are VERY irregular in shape -- more of an ink splat than a uniform, bushing-ready hole. Regards, RAF
  12. TpaRAF

    Filler for structural bolt holes

    Thanks for the suggestions, eromliGnoD & Hydtools. The condition is a thin flange plate with irregular corrosion around the original rivet hole. The repair consists of grinding the hole back to clean, sound metal then adding scab plates to restore section. The proposed bolts are ~3/4"...
  13. TpaRAF

    Filler for structural bolt holes

    Hi, CivilPerson: Thanks for your input, but no joy on doing this. These are main girders on a bridge. Florida prohibits field welding; HAZ is an issue; punching not practical in-situ. RAF
  14. TpaRAF

    Filler for structural bolt holes

    We are working on a bridge repair project, replacing rivets in deteriorated structural steel with high-strength bolts. In some locations, the hole is several times the replacement bolt diametre. The concern when the bolts are torqued to provide a slip-critical connection, the scab plates...
  15. TpaRAF

    US Customary vs. metric units

    The dimensional issues have been discussed throughly; what about the stresses and strengths? I'm not so sure about the dual-plans approach. I would stick to dual units on one plan for measures and capacities. If you're the engineer, shop drawings have to be prepared to your satisfaction. It...
  16. TpaRAF

    Strengthing of Existing RC Columns

    For bridge repairs in Florida, we often use reinforced concrete jackets (6" to 9" thick). This is because of severe section loss, though. Also, sesmic resistance is not a consideration. If your goal is just increasing axial capacity, concrete alone might work (compression only). Surface prep...
  17. TpaRAF

    RE: Trucks vs. Cars

    The AASHTO LRFD design code uses a notional vehicle, which is a three axle truck, along with a uniform lane load. The design vehicles also include a tandem truck and the military loading. All these add extra axles to the loading. So ... I think MotorCity's opinion of the design load is correct...
  18. TpaRAF

    Hand hole design in steel poles.

    Please see thread794-119271 "Openings in cylindrical shells". Also visit http://www.dot.state.fl.us/structures/proglib.htm and look at the reference files for the Mastarm program. MathCAD is required, but I can send you a PDF if that would help. My application was also for traffic and overhead...
  19. TpaRAF

    LRFD concrete slab design - fatigue experience

    I am designing a 3-span continuous, reinforced concrete flat slab bridge using LRFD methods. The fatigue loads do not seem to be influencing the design! What is your experience on this? In my past experience with LFD / AWS slab design methods, the flexural reinforcing, then the fatigue reinf...
  20. TpaRAF

    LRFD limits for max reinforcement dropped??

    I have a prestressed flat slab design that exceeds the older c/d limits. In the latest edition of the AASHTO LRFD Bridge Design specs, the check for "c/d < 0.42" has been dropped [§5.7.3.3]. The code appears to address this by applying a reduction to the phi factor when the section is...

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