huangyhg

aci 318 - older version
i am looking at an older copy of aci 318. it is from the '70's. incredibly thin, i might add!!
for the flexurl and axial loads chapter, it doesn't seem to have a lot of the information i would have expected. there is no formula for a maximum axial load that accounts for the minimum eccentricity (similar to the 0.8 factor in today's code on top of the phi factor).
are you just expected to use the principles of mechanics of materials to determine the allowable compressive load? i noticed that there is a minimum eccentricity specified in this code, but it looks similar to the current requirements (although i believe it is slightly higher).
can anyone provide any insight?
my boss loves to use the crsi books for things like that. i think that was common practice then. we have a few of those from the 70's in our office. see if you have any of those for reference.
rc
all that is necessary for the triumph of evil is that good men do nothing.
edmund burke
structuraleit - you are right, use engineering principles to work out an answer. systems of printed graphs, charts and table were heavily relied on for code compliance and nomographs were sometimes used, too. understanding the "problem" was more important because you often did not have the calculating tools available to solve the "real" situation. you had to analyze a "simplified" model (that you created yourself using reasonable assumptions).
readily available calculators and computers have allowed more sophisticated problem solving.
structuraleit,
i believe that aci 318-63 introduced the engeering world to "ultimate strength design", which we now call strength design. that code did not have a commentary. the load factors have changed and more "stuff" to check has been added but the basic principles really haven't changes for 45 years.
the current aci 318 code is more like a text book but without example problems.
thank you all who have replied. in reading through the commentary of aci 318-05, they reference the aci318-71 when they talk about getting rid of the minimum eccentricity in favor of the 0.8 factor.
while they talk about the idea that the factors (0.8 for ties columns and 0.85 for spiral columns) correlate very closely to the minimum eccentricities of 0.05h (for spiral columns) and 0.1h (for tied columns), the only real difference i see is that before they introduced the additional factor of 0.8/0.85, aci didn't recognize a compression only
that older code has a nifty set of charts for two way slabs with different end conditions for max positive moment, mas negative moments, and max shear. of course, those charts are not part of the current code for some unknown and probably asinine reason. you can still find these charts in some concrete text books.
structuraleit,
the short answer to your question is:"yes, that is probably accurate".
for the explaination that you probably want, the text book, "design of reinforced concrete,seventh edition" by jack c. mccormac & james k. nelson, chapter 9 goes through where the equations in the code came from.
i hope that this helps.

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