Concrete Shear stress per 1963 ACI code

[jmm28]

I am trying to confirm the shear strength of a beam that was originally designed to the 1963 code. Based on the current code the beam does not have the proper shear strength, but we want to verify that the beam met the code at the time it was designed. I can't find a copy of the ACI 318-63 code and wanted to know if there was anyone out there that could help me with what the concrete allowable unit stress was per the '63 code and what the design shear equation was at this time and the requirements for minimum shear reinforcing. Any help would be appreciated.

 

[SlideRuleEra]

The 1963 issue of ACI 318 was the first to incorporate strength design. I don't have a copy of that edition, but it can be purchased, on CD, from the Portland Cement Association at this link:

http://www.concrete.org/BookstoreNet/ProductDetail.aspx?ItemID=318CENCD

Even if the beam does not pass using 1963 strength design criteria, be sure to check it using 1963 working stress requirements - either approach would have been acceptable using that code edition.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[jmm28]

Thanks. I did find that and we are looking to purchase it, but I am in a bit of a time crunch. I do know that the original beam was designed to the working stress design per the 1963 code based on the general notes in the exitsing drawings.

 

[SlideRuleEra]

From ACI 318-63, Allowable Shear Stress, Working Stress Design, for normal weight concrete:

Beams Without Web Reinforcement
f_v = 1.1 x (f_c^')^0.5

Beams With "Proper" Web Reinforcement
f_v = 5 x (f_c^')^0.5

These are the allowable values, as usual, to really evaluate what you have "the devil is in the details"... most likely will have to go through the complete Working Stress design to see exactly what was done.

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[BAretired]

I have a copy of ACI 318-63. Chapter 12 deals with Shear and Diagonal Tension - Working sStress design. Chapter 17 deals with Shear and Diagonal Tension - Ultimate strenth design.

Do you need a copy of both?

BA

 

[jmm28]

Yes, a copy of both would greatly be appreciated. Thanks everyone for their help!

 

[BAretired]

Here is the first part. My scanner is a bit slow, so give me a few minutes for the second part.

BA

 

[BAretired]

Here is Chapter 17.

BA

 

[hokie66]

You also need to know that in the 1963 code the capacity reduction factor for diagonal tension was 0.85, and the load factors were 1.5 and 1.8. Shear reinforcement most likely Grade 40.

 

[BAretired]

Good point, hokie. Here is Chapter 15.

BA

 

[jmm28]

Thanks everyone! I think I have everything I need now.

 

[weab]

Wow!! Oh, the simplicity of the '63 code!

 

[hokie66]

ACI318-1963, the most important structural engineering document of the 20th century, in my estimation. But then I may be biased, as it is the one I started with.

 

[BAretired]

I agree with you, hokie and here are the names of the members of the ACI 318 Committee. A veritable who's who in the field of concrete engineering.

BA

 

[hokie66]

Yeah, those guys knew/know their stuff. George Winter's text was the one we used. It is amazing how many of the provisions of that code remain essentially unchanged, but just explained in many more words.

 

[dhengr]

hokie, Dick Barker obviously took his copy of George Winter’s book with him when he left here for VT, because that was the first concrete text book we really used too. Although, we started out with a text by Phil Ferguson and the 56ed. of ACI, we switched in mid-stream. And, re: ACI318-63, the thing that amazes me is that having studied texts by several of those committee members, we actually had a fairly good understanding of the code and its origins. We designed a bunch of structures using that code and despite its simplicity of use, generally understandable presentation, and lack of many adjustment factors on loads and materials, those structures are still standing and functioning all these years later. Now it seems that they teach little about how concrete and the structure really act and work, but spend hours haggling over whether an adjustment factor should be .85 or .9 and whether it only applies if the wind is blowing from the left or below. I’m kidding a bit, but we designed entire concrete buildings without much more effort than goes into load combination tabulation, and load factor adjustments for various design considerations with today’s approach and codes. Remember when essentially the whole steel and concrete codes were just reprinted as part of the UBC? And, that entire code was a 5"x8"x1.5" thick book; now you need a separate shelf for each of these codes.

 

[hokie66]

I didn't know Prof Barker brought his Winter with him, but I remember it was well worn. Mine is still in use, but my ACI318-63 is coming apart. Other than the torsion provisions, I don't see the later codes as being better than the 1963 version.