Reinforcement Laps

[engstructural]

BS 8110 Design

I aeem to recall that for a bar to be effectively lapped for continuity the bars must be within a certain distance of each other. Can anyone tell me where I can find the guidance on this?

 

[NS4U]

ACI 12.14.2.3

 

[youngstructural]

Actually the lap length may be extended to continue considering continuity, however generally lapped bars at an unadjusted lap length are considered to be in direct contact (ie: tied).

Hopefully someone posts more info for your code, however I have just had to detail bar lapping, etc, for an external reviewer on the stadium I've designed the cross and long frames on... If no one posts further info for your code, I'd be happy to post what I know based on NZS 3101.

And remember that there are two different schools of thought about how laps work, but the ACI committee 408 report is pretty much the world standard, so you could purchase that from the ACI website. I've not read it, but it is apparently quite good.

Cheers,

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[NS4U]

YS-

I quickly read over the 408 R-03 report. It did not go into significant detail as to the mechanics of lap splices and pretty much just reiterates the code provisions. Do you know of any other material which may explain the mechanics in greater detail? Particularly a discussion regarding splice failure at wide spacing.

 

[youngstructural]

Morning NS4U,

I should have been more clear; The 1992 report, 408.2R-92 (reaffirmed 2005) is more detailed.

Also, there are a good number of texts which deal with this, although I suspect you'll need to look into the published academic papers upon which the reports were written if you want a detailed, in depth, discussion of the mechanics.

I'm borrowing a copy of 408.2R-92 from the local University tonight, so I can post to let you know if it has a specific discussion about splice failure at wide spacing.

Regards,

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[NS4U]

Thanks YS, I have 408.2R-92 here and will look over it tonight as well.

I am very curious of this 5:1 slope they speak of, and why only they did not test bars greater than 6 in apart.

 

[engstructural]

thanks guys,

Can anyone advise me of the size of gap or spacer I can use between main bars and curtailmnet reinforcement for beams at supports. (2 Dia. etc. ??)

 

[patswfc]

Look at clause 5.4.3 and Fig. 5.5 of Standard Method of Detailing Structural Concrete 3rd Ed.
The gap can be upto 4d or 50mm for standard lap lengths, if the gap is bigger then the lap has to be increased in length.

 

[engstructural]

Thanks Pat that was the reference I was looking for.

I seem to remember from an old post you were sitting the Part 3 IStructE. How did you get on.