LRFD Philosopy of Sheet Piles
LRFD Philosopy of Sheet Piles
(OP)
This is a continuation of thread255-142962: Sheet Pile Retaining Walls - LRFD.
It appears the implemention of LRFD for these types of structures is very premature.
see pubs.nrc-cnrc.gc.ca/rp/rppdf/t96-107.pdf
The whole point of this type of change is to reflect the increase in knowledge in our field. The limit state philosophy here leads to more conservative designs. The authors suggest a new approach is required to make it more in line with WSD.
Comments?
It appears the implemention of LRFD for these types of structures is very premature.
see pubs.nrc-cnrc.gc.ca/rp/rppdf/t96-107.pdf
The whole point of this type of change is to reflect the increase in knowledge in our field. The limit state philosophy here leads to more conservative designs. The authors suggest a new approach is required to make it more in line with WSD.
Comments?





RE: LRFD Philosopy of Sheet Piles
At IFCEE09 in Orlando, Jerry DiMaggio, late of FHWA, agreed that better calibration of the LRFD factors for many geotechnical problems related to earth retention and slope stability (could be argued they both belong to a meta-set of general slope stability) needs to be undertaken.
Being currently involved with the design of cantilevered and anchored earth retention systems, I do note that the LRFD approach can be very conservative with respect to traditional ASD or WSD practice in terms of an equivalent factor of safety.
However, it has to be recognized that there is no direct correlation between a traditional factor of safety and (the LRFD concept of) reliability.
For example, how reliable is a system with a global FS of 1.25? What is the likelihood that the system will fail this limit state (probability of failure in 100 years)? The answer cannot be directly computed from the "lumped" FS.
Jeff
RE: LRFD Philosopy of Sheet Piles
RE: LRFD Philosopy of Sheet Piles
RE: LRFD Philosopy of Sheet Piles
RE: LRFD Philosopy of Sheet Piles
a.) Low safety of structures being designed.
b.) High cost of structures being designed.
c.) Irrational approach of structures being designed.
d.) other???
RE: LRFD Philosopy of Sheet Piles
RE: LRFD Philosopy of Sheet Piles
RE: LRFD Philosopy of Sheet Piles
The lack of transparency into how resistance or load factors are arrived at is also an issue to be dealt with. However, I expect that the situation is improving and will continue to improve. For example, I am currently working on the design of several retaining structures that will support traffic. The AASHTO LRFD provision dealing with lateral surcharge due to traffic loading does, in the accompanying commentary, cite the published research and briefly describe the methodology used to develop the guidance.
Don't throw the baby out with the bathwater, folks.
Jeff