Construction Joints and Control Joints - Spacing Limits 2

[mdmiller]

I have always seen 30'-0" limit to the spacing of construction joints for exposed walls and 60'-0" limit for unexposed walls. Why is this? Is this referenced somewhere in ACI? Can these limits be increase if you are using the minimum temp. & shrinkage reinforcing? What if you cut every other bar at the construction joint? Can you use crack control joints in place of construction joints and pour longer lengths?

Thank you!!

 

[JedClampett]

It's customary practice that's worked well for many years. There's no code requirement, except maybe if you're under the auspices of ACI 350.
To answer your other questions, all those things contribute to good crack control, but you're better be 100% confident before you exceed customary guidelines. Because if there's a problem, some engineer will be glad to testify that you violated these guidelines.
That being said, I've went to 40 ft and beyond many times. We use .005 temperature and shrinkage steel.

 

[cvlenv]

to jedclampelt : could the 0.005 steel ratio be adaptable to water retaining tank walls?

 

[rowingengineer]

Cvlenv, While Jed will more than likely handle this question with the greatest of ease you may wish to ask this as a new topic.

An expert is a man who has made all the mistakes which can be made in a very narrow field

 

[JedClampett]

Gracias, rowingengineer. But I hate to leave this unanswered.
The .005 reinforcing ratio (we top out at .0052) is actually from ACI 350, the code for Environmental Concrete Structures. So it would apply for water retaining walls. It's a requirement for temperature and shrinkage reinforcing based on movement joint spacing. And since we always violate the spacing of movement joints (40') we always use the .0052 ratio.

 

[cvlenv]

thanks JedClampett!