Underpinning and increment connections
Underpinning and increment connections
(OP)
I have never done this before so it may sound pretty basic. When we do underpinning, how do we want to connect the rebar of each increment? Specifically, we are looking at giving more depth to the walls of a rowhouse so the basements extends to 7.5ft from the existing 5ft depth. We consider doing that in increments of 4ft, with 1ft thickness and the depth of 2.5 ft. I am not sure how the rebar from each segment of concrete shall connect to the next segment. We consider having rebar extend its development length into the next segment. Should that be the appropriate way to connect the segments?
Thanks!
Thanks!






RE: Underpinning and increment connections
RE: Underpinning and increment connections
RE: Underpinning and increment connections
RE: Underpinning and increment connections
My understanding of the detail is that the new concrete is placed underneath the existing 5 ft tall basement walls.
I usually find that vertical bending is the way that such a foundation wall will behave. Size and placement of the underpin is critical to dealing with bending behavior whatever direction it is occurring in. Arguably there is a significant horizontal reaction at the base of the existing 5 ft wall (and therefore the top of the new underpins) and so horizontal bending would need to be addressed. I would not expect that a 2 ft lap of a #6 bar would be adequate but much would depend on the size and positioning of the underpins, composition and thickness of the existing walls etc..
RE: Underpinning and increment connections
RE: Underpinning and increment connections
For the front, I was considering using some vertical rebars and make the segments thicker, but that was just a thought out of the box.
RE: Underpinning and increment connections