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Recent content by MIKE_311

  1. MIKE_311

    Steel Bearing - bridge Anchor Rod Design

    I have reduce the forces in the design of a traction frame by using an analytical model we developed, but for the bearing design we use the calculated loads. In your case it wouldn't be worth it to try to model it. Probably best to just add more anchor bolts and move on to the next task.
  2. MIKE_311

    Old Through Plate Girder Bridge

    Engineering judgement ratings are a thing. If the bridge is in good condition, are you able to do a comparison of the original design load to current pedestrian/maintenance vehicle loadings? RR bridges are usually fatigue/service controlled and are often well overdesigned for strength.
  3. MIKE_311

    Steel Bearing - bridge Anchor Rod Design

    Typically, if I cant reduce the height of the bolt for bending, I will weld collars to the masonry or sole plate to reduce the bending length, but adding more bolts is what I try to do first. Also, make sure you aren't including the nosing loads in the lateral force calculations, generally the...
  4. MIKE_311

    Evaluating the stability of a single I beam

    I don't want fixed ends. I want to ensure the top flange is braced at the end and since is going to be sitting on its own, and relatively deep, the entire beam is stable. The concrete infill is only being proposed for stability. I added a sketch.
  5. MIKE_311

    Evaluating the stability of a single I beam

    I'll add a sketch, but the analysis is basically a single beam on two bearing supports with a moving concentrated load. Simple statics/mechanics 101 problem, but the assumption that the top of beam ends are braced laterally is removed, so L/r would not be valid as K =/= 1 for the top compression...
  6. MIKE_311

    Evaluating the stability of a single I beam

    I am working on a design where I have 2 simply supported, single span (30ft), deep steel I beams (80" deep, 24" flanges) that will be used as supports for moving concentrated load (~1000 kip) on the top of each flange. ~3" thick flanges and webs. The beams are too far apart (50ft) to tie them...
  7. MIKE_311

    Railway bridge loads

    I'm looking at a protentional redesign of rail bridge. The design calls for and EMD SD70 Locomotive, 33,700 Gallon DOT 112 Tank Car, and a Cooper E60. AREMA only discusses design using the E80, the E60 is easy enough but I can't seem to find anything on the other two loads. Sample calcs...
  8. MIKE_311

    Fire Stand pipe attached to bridge

    I have a bridge replacement project where we need to remove and replace a fire stand pipe attached to the bridge structure that is being replaced. The standpipe will extend from the top of deck down into a tidal waterway. The bridge size or geometry itself does not fire a standpipe, it's mainly...
  9. MIKE_311

    Span configuration for tall bridge in horizontal curvature

    In water work can be expensive plus the impacts of scour and H&H on the design, not to mention any permitting and approvals. If you can keep piers out of the water, that's where I would start.
  10. MIKE_311

    Continuous Flight Auger pile design

    I need to design some CFAs. Basically a steel micropile tube pushed into grout. From what I gather they are designed either as micropiles or drilled shafts. These are small diameter CFA and will be seeing some moment. AASHTO doesn't really provide any guidance for design other than axial...
  11. MIKE_311

    Bearing Pad Check

    Is the bearing pad offset or the girder? Isn't there an end diaphragm there? wouldn't that inhibit the placement of a diaphragm or the cross frames near girder end? I would have them jack and reset it or THEY should demonstrate it's ok to leave as is. You shouldn't have to justify a contractor...
  12. MIKE_311

    Design prestressed bridge beam for long term downward camber

    . Thanks. Im not sure the owner knows either which is what is leading to our confusion on the subject, and admittedly I am not a PS beam expert. I can design one easy enough but I don't have experience with long-term performance. Their design manual, used to say, "negative final camber of...
  13. MIKE_311

    Design prestressed bridge beam for long term downward camber

    Thanks, let me restate, the owner says no downward deflection to ensure there will be no tension in the bottom of the beam (for cracking). I agree, downward camber does not equal tension. But simply designing for service loads I don't think is enough as the issue is that long term effects...
  14. MIKE_311

    Design prestressed bridge beam for long term downward camber

    The bridge owner doesn't want any downward camber in the long term (i.e. no tension in the PS beam bottom flange over time). PCI has a procedure for estimating long term camber from creep and shrinkage using multipliers, but states that these multipliers are not applicable to bridges with...
  15. MIKE_311

    Tall Integral Abutment Sample Plans

    That's a tall abutment. How do you manage the earth loads and provide retaining walls? typically, what I have seen is to use a shorter integral or semi-integral stub abutment behind a MSE or other retaining wall. This way the wall holds back the earth and the abutment carries the vertical and a...
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