Reinforcing Opening in Existing Vault

[AMS-12]

Hello,

Working on a gravity stormwater design and we need to connect to an existing cast in place vault with the dimensions of 16'x9', depth 9.5', vault floor is 11.5' below grade. The walls are 10" thick with assuming #5 10"oc horz and vert. Need to core a 42" opening into the 16' side, the core will be centred horizontally and bottom of core is approximately 1.75' up from the vault floor.

That said there are no as-built reinforcement detail drawings, dimensions are pulled from site photos and general detail drawings, see attached.

The approach to reinforce the cored wall, is to cast a new reinforced wall of the same dimensions on the exterior of the vault against the existing wall, with the new wall reinforced to take into account the 42" opening and redistributing the loads from the cut section to the adjacent continuous sections, I have been directed to design assuming end supported beams around the opening, initial calcs indicate about 5% reinforcing steel by area in the lower beam.

Another option I'm considering proposing to the team is designing a 2 way slab and using the guidance to replace the cut bars on either side of the opening, though I cant find that standard described anywhere.

Conceptually is pouring a new wall with known reinforcement design against an existing wall a viable option?

Thanks for any input.

 

[HTURKAK]

You did not define the new connection 42" pipe material. I wish the new pipe would have the same soffit level with 7ft dia storm drain.

I would core the 16' side wall with dia 60 in. then cut and bend the existing reinf. towards outside add new rebars then construct a RC square reinf. pad / neck at extior side with dims. 70in X 70in and thk 10 in.



According to the grace of God which is given
unto me, as a wise masterbuilder, I have laid the foundation, and another buildeth thereon. . . .
I Corinthians 3:10

 

[AMS-12]

The pipe is a 30in RCP, 37in OD, assuming a 42" core. To clarify, remove concrete and preserve the reinforcement, cut the center of each rebar intercepted and bend to the exterior of vault. Splice in new rebar that will tie into a new renif. Pad?

Thanks for your advice!

 

[BridgeSmith]

I suggest you start by quantifying the loads, and then ask you RCP supplier if the pipe can withstand the loads, or can be made to withstand the loads. If they can make it work (which I suspect they can), you don't have to do anything except grout the annular space. Obviously, you'd still have to extend the wall rebar a few inches, to stabilize the grout.

 

[HTURKAK]

Core dia in the range of 57 in.I draw a simple sketch . The socket piece should be fixed to the conc.

According to the grace of God which is given
unto me, as a wise masterbuilder, I have laid the foundation, and another buildeth thereon. . . .
I Corinthians 3:10

 

[AMS-12]

Thanks for the clarification.