Appendix D ACI 318-02 1

[chasl]

Has anyone questioned the difference in steel anchor bolt shear capacity between the values in AISC (9th) Table ID vs. the value obtained from ACI 318-02 equation (D-17) in appendix D? The values appear to disagree by a significant amount. Am I missing something here?

Thanks for any comments or help.

 

[JAE]

Isn't the 9th Edition, AISC an ASD design method and the ACI 318-02 a factored design?

 

[chasl]

Even factoring out the load factors and undercapacity factor there is a difference in the indicated capacity of the anchors in shear when calculating shear capacity of the steel. Guess it just points out the conservative nature of ASD.

 

[CSEllc]

I haven't looked at the values, but, I don't think it has to do with "the conservative nature of ASD", i think it has to do with the fact the values in the 9th editiona re based on research that was done nearly 20 years ago....remember the 9th ed first came out in 1989. The ACI 318-02 values are based on research that was done much later.....within the last 8-10 years.

How do the values compare with ACI 318-89?

 

[UcfSE]

AISC 9th edition, the shear table 1-D, Fv=0.17Fu or 0.22Fu. ACI App D uses phi*Fu where phi ranges from around 0.60 bottom (unless its post-installed) to 0.75. So we are comparing 0.17 to say 0.7 *Fu. That's quite a difference. I think it has to do a lot with advances in research as CSE stated along with the difference in design principle of ASD vs. LRFD. Remember also that we are comparing a limit state strength to a service state strength and dividing out safety factors and such to convert from one to the other is roughly approximate at best. If you read the commentary in the ACI RD.6.1.2 the bolt strengths where calibrated to give results consistent with AISC LRFD Specs, not ASD.