development lengths

[preynolds]

I have been comparing the AASHTO development lengths with the ACI development lengths. The AASHTO dl's are still using the 1989 ACI code to determine the lengths, but ACI adopted their current ld equation for the 1995 code (I believe). It seems to me that the current ACI code is giving ld that is sometimes twice as long as required by AASHTO or the old ACI. Am I missing the boat on something or has anybody else experienced this? I have a retaining wall for a municipality and right or wrong, I am using a combination of ACI and AASHTO codes to design. However, what should be done when the two codes contradict each other. The municipality has not required a specific code.

thanks for any help

 

[ishvaaag]

Material and structural expenditure is more than anything growing as the codes progress. Only the advance of materials partly counteracts this. In any case, the more modern codes embed the best knowledge to their specifiers known, and so the more modern ACI code should give better and more consistent performance.

The process has also been seen in Spain. Present development and splice lengths are longer than they were.

So except the authorizing reviewing party asks otherwise, the best would be to follow the ACI code, more when it is conservative respect the other. Were the contrary the case, we could think that specific charactestics of the works covered by the code caused such higher demand and then I would recommend the AASHTO ones (in more than just safety) but it seems it is not the case.

 

[preynolds]

ishvaag

upon further review of the ACI code, it seems that the ld for equations under 12.2.2 can be considerably more than the ld for equation 12-1 in section 12.2.3. I guess I should have looked at things closer. Thanks for your help