AASHTO Rock Socket Side Resistance
AASHTO Rock Socket Side Resistance
(OP)
The formula given in Article 4.6.5.3.1 of AASHTO HB-17 (page 85) for ultimate side resistance reads as follows:
Qsr = (pi)*Br*Dr*(0.144*qsr)
Yet the label on the y-axis for Figure 4.6.5.3.1A indicates that qsr is the unit side resistance.
Should the formula read:
Qsr = (pi)*Br*Dr*(144*qsr)
to make the units work out?! Or do they intend to reduce Qsr by a factor of 1000 for some reason?!
All responses welcome.
Note: Originally posted in AASHTO Code Forum.
Jeff
Qsr = (pi)*Br*Dr*(0.144*qsr)
Yet the label on the y-axis for Figure 4.6.5.3.1A indicates that qsr is the unit side resistance.
Should the formula read:
Qsr = (pi)*Br*Dr*(144*qsr)
to make the units work out?! Or do they intend to reduce Qsr by a factor of 1000 for some reason?!
All responses welcome.
Note: Originally posted in AASHTO Code Forum.
Jeff
Jeffrey T. Donville, PE
TTL Associates, Inc.
www.ttlassoc.com





RE: AASHTO Rock Socket Side Resistance
(12 in/ft)^2
---------------
1000 lb/kip
The notation and the units for each symbol can be found in Sectino 4.6.2 on page 79.
RE: AASHTO Rock Socket Side Resistance
Thanks for the explanation. I had not considered that the units of Qsr would be specified.
Jeff
Jeffrey T. Donville, PE
TTL Associates, Inc.
www.ttlassoc.com
RE: AASHTO Rock Socket Side Resistance
I posted the thread "DS Uplift Capacity with Socket". Does the AASHTO HB-17 publication address total side resistance (soil resistance + socket resistance) and the resistance distribution along the shaft? I'm looking at uplift capacity from soil and socket contribution.
Is the publication available on-line?
Jefferys
RE: AASHTO Rock Socket Side Resistance
HB-17 is the AASHTO Standard Specifications for Highway Bridges, 17th Edition (2002). It is most definitely not free (unfortunately)! Copies are available from AASHTO (www.aashto.org). However, Amazon.com and ebay might have 3rd-party (used) copies available. Note that this version will be officially deprecated for highway structure design in a year or two when the LRFD version will be the "official" design basis for federally-funded projects (and likely many state projects, too).
Unfortunately, the document does not give any specific guidance on this topic - which I am pained to admit that I don't know as much about as I should. I am currently looking at DSs with rock sockets for a current project, but they are fortunately short (<15 ft OA) and I will assume negligible contribution from the soil for skin friction.
Off the top of my head, I don't know of any source giving explicit design guidance. But please do let us all know if you find some.
Jeff
Jeffrey T. Donville, PE
TTL Associates, Inc.
www.ttlassoc.com