elevated deck slab contraction joint

[delagina]

been reading conflicting things online with regards to elevated deck slab. should i or should i not put CJ for reinforced elevated deck slab.

also please comment on my cj location, if cj is preferable.

thanks,

 

[JAE]

I never use them on elevated slabs. Never.

 

[spats]

This question has come up on more than a few occasions. I suggest you search this Forum to find your answer.

 

[dcarr82775]

I'm with JAE, you do not put contraction joints in elevated slabs. If you put them in you need to check the slab for the bending/shear at the reduced section depth.

 

[rowingengineer]

Don't do it, just don't do it.

ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION.”

 

[BAretired]

I agree that there should be no contraction joint in a suspended slab.

BA

 

[hokie66]

In the picture shown, there certainly should be not contraction joints. But I think is is an overgeneralization to say never. What a lot of people call expansion joints are really for contraction.

 

[ltlspf]

If you have a one way elevated slab, would there be any issues with contraction joints parallel to the slab span? Seems like it would be beneficial if the slab has an exposed finish?

 

[hokie66]

A joint parallel to the span could be considered, but you might want to explain further how this is beneficial to the finish. You have to assess what effect a joint has on the overall structural stability of the building.

 

[ltlspf]

The joint would minimize random shrinkage cracking in the slab, maintaining a cleaner appearance. The ones we have specified would allow horizontal movement but not vertical. And yes that's a good point, the use of the diaphragm would have to work around the joints.