Construction Joints in Concrete

[CivilTanju]

Hi all,

Is there any requirements for construction joints when designing water towers, shear-walls, retaining walls, slabs etc? The requirements that i have seen in ACI/UBC-97 leads me to the "shear-friction" calculation. Just taking into account the "shear-friction" calculation may we create construction joints verticaly in retaining walls, elevator shear-walls etc.

regards,

 

[youngstructural]

My short answer: "Yes"; Control, construction & separation joints are necessary to all structures. Depending on how bit a structure is your control joints may simply be the ends of the structure, so given a small enough structure you don't need to introduce control joints, just show that they would be necessary at larger increments that the size of your structure.

You should look at ACI 224.3R; "Joints in Concrete Construction"... It has various chapters on a variety of different structures and elements. I have found it to be an authoritative and useful document.

Remember, unless you're working under a prescriptive code you never HAVE to do anything, by code or otherwise. If you are working under a prescriptive code you should simply be referring to it for your requirements. Otherwise you do have to satisfy yourself that your structure will meet all SLS and ULS criteria, and typically that would require construction joints. You might be able to reinforce your section sufficiently to negate that need however.

Good luck,

YS

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

 

[CivilTanju]

hi YS,

i completely agree with you about control and seperation(dilatation) joints. As long as they allow the free-movement(depends on DOF of joint) of super-structure due to the enviromental effects.

What i intended actually to be answered is: For the concrete that we couldn't cast monolitically because of
huge amount of concreting area (slabs, walls, columns etc. ) may we make the vertical construction joints even
if we are in highly risky seismic zone and have to get stuck strictly with prescriptive code?

I got the copy of ACI 224.3R and it doesn't mention the seismic loading.