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...
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?
1503-44 -- I think that's a fair concern and it was only recently that I saw it to be a normal (or at least not unusual) assumption, for example in FHWA's example here (Step P.6), "Ultimate axial compressive resistance is determined in accordance with either equation 6.9.4.1-1 or 6.9.4.1-2. The...
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...
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.
Hi all,
I just had a general question about the calculation of the AREMA rocking component of impact in beam spans, particularly as shown in an example of John Unsworth's "Design and Construction of Modern Steel Railway Bridges." As shown in the attachment (hopefully), the cross-section in...
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...
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...
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...
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...
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...
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...
Can you explain the difficulty you're encountering with Allowable Stress Rating a little more? Is it just tracking down the right allowable stress for the failure modes you mentioned? Otherwise, if you can determine the capacity through allowable stresses from MBE and force effects through one...
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...
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...
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...
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...
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!
