Guidance on CSA A23.3 - Appendix B

[CABaker]

I'm trying to get some background information on the tables for two-way slab design (with rigid edge supports) in the Canadian concrete code. I've been searching the usual journal for a direct reference but have come up empty.

Does anyone understand the historical development of these tables, some parts are definitely elastic plate analysis but other appear to be yield-line.

If anyone has any guidance it would be much appreciated.

 

[KootK]

Are you referring to the direct design method or the tabulated information for single plates with various end conditions given in the appendix?

 

[CABaker]

Tabluated information - specifically Table B.1.

 

[KootK]

Ahhh... just like you said in the title. I always just assumed those were elastic analyses. I'm suprised to hear that they're not. How have you verified that they are not elastic plate results?

 

[CABaker]

Yes, a great deal of them are. I did some finite element plate analysis for Cases 1-3, and the ones I did came out elastic.

My design case was for Case 9 with and length aspect ratio of 0.85. The 0.072 is about 1/2 of what you get with elastic analysis.

I'm past the engineering phase of this project, I'm just looking to understand the table and how it was developed over time. Before I spend a lot of time crunching numbers I thought I'd check around to see if anyone else ran into this before.

I see some similar tables in the code from 1959, and I've been through the 'easy to find' research from as far back Westergaard and Slater (1921) all the way up to Baker and Drysdale's (2005) similar work with masonry wall panels. Some similar tables are included in the Canada Masonry Code S304.1-04 for simply supported cases. Those tables are governed by different analyses for different sections of the table (elastic, failure line and strip method). I had a hunch the same was true for the A23.3 B tables.

These tables seemed to 'reappear' in the CSA code in late 1970's after being removed for a couple of code cycles. I was hoping to find journal paper that explained why it was brought back into the code from around the vintage, but I haven't had much luck with ACI or the Canadian Journal of Civil Engineering.

 

[KootK]

Well, if you do find the information that you're looking for, please post the results. I've used those tables on several occasions.

 

[dgkhan]

I have it in Design of concrete structures by Winter and Nilson which is based on ACI code. I guess call somebody in ACI, farmington hills, Michigan. They might be able to help you.