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  1. jrw501

    Allowable Stress Design/Rating of Driven H Piles

    Gotcha, that makes sense. I think I was having what might amount to some magical or wishful thinking that the capacity might be limited to 0.25Fy so that during driving they could get these things into the ground without damaging the pile, but after they were driven to refusal and survived the...
  2. jrw501

    Allowable Stress Design/Rating of Driven H Piles

    Is it the case then that the 0.25Fy (or 0.33Fy) is primarily to make sure the piles can be driven safely? For evaluation of an existing pile for design loads, wouldn't using 0.25Fy be pretty conservative in that case?
  3. jrw501

    Allowable Stress Design/Rating of Driven H Piles

    ...For example, was it the case that engineers used to just find the pile reaction from simplified analysis (Pile Reaction = P/# piles + M*x/Iy_pilegroup + M*y/Ix_pilegroup) and they used a lower allowable stress because they weren't accounting for any soil-structure interaction or moment in the...
  4. jrw501

    Allowable Stress Design/Rating of Driven H Piles

    Hi all, I'm looking at an old bridge pier foundation, with a pile cap supported on H-piles. The piles go mostly through sand and are tipped in shale. On the structural capacity side, using allowable stress design, the AASHTO Std. Specs (which I'm less familiar with compared to the LRFD) limit...
  5. jrw501

    LEAP Consys

    In addition to robust analysis programs that are capable of a lot more (SAP2000, LUSAS, etc...), we have occasionally used GoBeam (https://yakpol.net/GoBeam.html) and PennDOT's CBA (continuous beam analysis) prgoram.
  6. jrw501

    AREMA Rocking Effect Question

    ...overturning couple is resolved to the center of the outer two beams on either side (8' between resisting beam groups), which results in a (0.2W)*(5')/(8') = 0.125W resisting couple. Unsworth then says this is translated into a rocking impact of 12.5% -- but isn't it the case in this example...
  7. jrw501

    Tremie Seal Weight on Piles?

    In this case it's 4' diameter steel pipe piles. Thankfully, all parties seems to be on board with including the weight at this point.
  8. jrw501

    Tremie Seal Weight on Piles?

    Thanks for the quick response. That is definitely our usual policy since as you've said we don't really want to be counting on the soil to be doing anything with bearing. It's come up as a question effectively by the contractor looking to shorten some pile lengths, but definitely seems...
  9. jrw501

    Tremie Seal Weight on Piles?

    In the final condition of the bridge with piers in water where they've performed cofferdam construction, would you typically assume that your piles are carrying the weight of the tremie seal ? My tendency would be to conservatively assume the weight of the tremie seal can be transferred...
  10. jrw501

    Plastic section modulus of a composite section

    You may find these useful: https://www.youtube.com/watch?v=1fzqBwZKLJQ&feature=youtu.be (the information I provided largely came from this presentation at NASCC last year). The effective stress-strain method is discussed at around 20:00. Direct interaction method around 46:00...
  11. jrw501

    Plastic section modulus of a composite section

    On the analysis side, for concrete-filled HSS AISC permits a few methods: -Plastic stress distribution, strain compatibility, elastic stress distribution method, effective stress-strain method. On the design/capacity side, for flexure: It's a function of member slenderness, equations are based...
  12. jrw501

    required to check adequacy of pier

    We've done something similar to what phamENG describes in some cases, I think mostly in design of fender systems. But for evaluating existing piers or designing new ones we just follow the AASHTO Vessel Collision Specs to determine the loads, which can obviously be quite significant depending on...
  13. jrw501

    required to check adequacy of pier

    You should be able to reasonably determine a design vessel (in addition ACoE and Coast Guard, you may simply find google maps helpful, since they often have images at the crossing, upstream or downstream that show water traffic) and in the absence of one, you may try to find a similar waterway...
  14. jrw501

    Rating a Shear Connection using Allowable Stress

    ...Load Effect)/(Live Load Effect)? If they have tension-equivalent allowables (yielding of gross section etc...), can you just use (tension allowable)*SQRT(3)/3 [from von mises]? Depending on the complicating factor, you may find useful information in a code like AREMA, which still commonly...
  15. jrw501

    AASHTO 3.10.9.2 Horizontal Connection Force

    You'd think so, right? But since this is Seismic Zone 1, AASHTO 5.11.2 (per my understanding) only requires the connection between the superstructure and substructure to be designed for that force, but not for the design of other structural components (outside of some column detailing depending...
  16. jrw501

    AASHTO 3.10.9.2 Horizontal Connection Force

    For the transverse direction I consider the other bearing assemblies since they are longitudinally guided disc bearings, but for the longitudinal direction the friction isn't enough for them to get 25% of their tributary length to the anchors/substructure. It also seems AASHTO wants me to...
  17. jrw501

    AASHTO 3.10.9.2 Horizontal Connection Force

    Thanks, the bridge seating meets the requirements and I'd have to check, but I don't think we see any uplift, it's just that 25% provision. AASHTO C6.13.2.12 refers us to ACI for the global design of anchorages to concrete (although I'm not a big fan of mixing and matching codes, especially in...
  18. jrw501

    AASHTO 3.10.9.2 Horizontal Connection Force

    I’m looking at designing anchor rods at a fixed pier of a 3 span continuous bridge (E-F-E-E) to meet AASHTO 3.10.9.2 requirements of the horizontal design connection force of 25% of the vertical reaction due to tributary permanent load and live load assumed to exist during an earthquake...
  19. jrw501

    AASHTO eta factors & deformation

    Perfect, that makes a lot of sense. Thanks crossframe & BridgeSmith!
  20. jrw501

    AASHTO eta factors & deformation

    This is the first project I've worked on with a non-unity factor (eta=1.05/0.95) where I've also been tasked with designing joints and bearings. I think the answer is yes, but thought I'd get some confirmation -- do the eta factors apply to deformations/movement ranges? Thanks!

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