Historical Lap Splice 4

[EDub24]

I'm reviewing an existing concrete and masonry structure that was designed in 1989. I can't find any information on the design code used but I would guess the ACI 318-83 that was revised in 1986. In the general notes section for the rebar lap splices I see this statement:

"UNLESS CALLED OUT OTHERWISE ON THE PLANS. THE LENGTH OF LAP SPLICES SHALL BE CLASS "B" WHERE NO MORE THAN 1/2 THE BARS ARE LAP SPLICED WITHIN THE LENGTH TABULATED BELOW AND CLASS "C" WHERE MORE THAN 1/2 THE BARS ARE LAP SPLICED WITHIN THE LENGTH TABULATED BELOW."

There is then a table that gives lap splice lengths for Class 'B' and Class 'C' for both 'top' and 'other' bars.

First off I'm not sure what are Class 'C' lap splices. I'm used to seeing Class 'A' and 'B'. Can anyone shed any light on this? Also this statement is confusing to me. How can I tell if a bar was spliced with the 'B' or 'C' lap splice lengths per the table? Can anyone shed any light on this? I trued searching for chapter 12 of ACI 318-83 but can't find it. Thanks!

 

[JAE]

ACI used to have A, B, and C splices in earlier code until they reduced it to two. I can get you a snippet of the relevant section in a day or two when I get back to my office.

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[Ingenuity]

From ACI 318-1983 Chapter 12:

ACI 318-1986 still had Class C splices. In ACI 318-1989 Class C splice designation was removed.

 

[JAE]

Bravo ingenuity

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[EDub24]

Thanks! I wonder what Class C laps were used for? Now I just need to figure out what that statement means regarding which splices are Class B and which are Class C...

 

[JAE]

The table that Ingenuity posted answers your question in that the table and the statement are consistent

The note you quoted says that when no more than 1/2 the bars are spliced across one spot the you can use a B splice. The bottom row of the table shows that if you splice 50% of the bars then Class B.

To know which splice they actually used you would have to obtain the rebar shop drawings...it depends on how they laid out the bars and whether they spliced all or 1/2 the bars.

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[SlideRuleEra]

I wonder what Class C laps were used for?

In that time period, we designated Class C for all rebar splices at our electric generating stations (Occupancy Category 4) because of high seismic requirement for the project sites.

http://www.SlideRuleEra.net

 

[BridgeSmith]

In the AASHTO bridge design spec. provision, which I understand are based on ACI, the class that was actually eliminated was the class B splice, with what was the class C splice becoming the new class B splice.

For bridge design we used Class C splices for everything (now class B). Of course, we rarely staggered splices, so 98% of the time, that's what we'd have to use anyway.

Just FYI, the "top bar" laps are longer for horizontal bars with 12" or more of monolithic concrete below and around the bars, due to the tendency of the bars to catch air bubbles migrating up through the wet concrete, which reduces the bond area along the bars.

 

[EDub24]

The table that Ingenuity posted answers your question in that the table and the statement are consistent

The note you quoted says that when no more than 1/2 the bars are spliced across one spot the you can use a B splice. The bottom row of the table shows that if you splice 50% of the bars then Class B.

To know which splice they actually used you would have to obtain the rebar shop drawings...it depends on how they laid out the bars and whether they spliced all or 1/2 the bars.

Thanks JAE. For some reason it didn't register in my head when I saw the table. Looks like for now i'll assume Class B laps unless the drawings specifically call for Class C since we don't have rebar shop drawings.

 

[JLNJ]

I'd like to register an official protest against calling something from 1989 "historical".

signed,

an engineering dinosaur (apparently)

 

[JAE]

I agree JLNJ. Unbelievably insensitive!

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[hokie66]

ACI 318-63 is classic, but it did create history.

 

[JLNJ]

JAE - pretty sweet picture. I like what it says about the user.

I'm sure we could do an entire thread with photos of dog-eared (read: loved) texts. Especially AISC's 9th edition.

 

[EDub24]

I'd like to register an official protest against calling something from 1989 "historical".

signed,

an engineering dinosaur (apparently)

Haha touche. I guess it's all about perspective.

 

[jgailla]

I have the one from 1928 or thereabouts. Found it at a used bookstore downtown.

 

[RickyTickyTavi]

I have all the historical ACI codes PDFed and on my personal cache of files. Theyre really useful to have.

ACI sells all of them up to 2005 for 200 dollars.

https://www.concrete.org/store/prod...SB&Format=USB&Language=English&Units=US_Units