Retaining wall to load bearing wall 2

[fcu45]

Hi

Case Information:
I have existing retaining walls sloped in the longitudinal direction (Triangular shape: base 60 meters and height 4.5 meters) and it is for the time being supporting internal soil fill for landscaping purpose, the distance between the two retaining walls is 15 meters).

Retaining walls are tapered 0.5 meter thick at bottom and 0.25 at top.

The client wants to utilize that place in more useful way by building one storey building, especially the structure is supported on piles.

Question:[highlight #CC0000][/highlight]
- What would be the best way to extend the existing sloped wall to the required 4.5 meters height?

My thinking is to chip top surface then Drill rebars into existing walls to work as starter bars but to what depth would be needed? or there is better solution?

Thanks

 

[BAretired]

In what part of the world is this located? Do you have frost in your locale? How deep are the existing retaining wall footings below grade? Do the walls have enough reinforcement on the outside face of each wall to resist lateral soil pressure? Are you going to consider the wall spanning from top to bottom? Or will you consider a hinge at the top of the existing wall?

A sketch might help.

BA

 

[fcu45]

Hi BAretired

Sketch is attached

- In what part of the world is this located?
Arabian gulf

- Do you have frost in your locale?
No

How deep are the existing retaining wall footings below grade?
Bellow the 4.5 retaining wall is 1 meter thick pile cap (Top surface of the cap is the same as ground level.
There is a space between the pile cap for each side that will be having tie beams connecting the two pile caps together.
See this section view:

http://files.engineering.com/getfile.aspx?folder=6f586c9c-fcd9-4d01-ba59-fc34c757bbf8&file=Ret1.pdf

Do the walls have enough reinforcement on the outside face of each wall to resist lateral soil pressure?
Yes

Are you going to consider the wall spanning from top to bottom? Or will you consider a hinge at the top of the existing wall?
I am not sure I understood your question, but I want to have single span roof made of HCS spanning between the two retaining walls and supported on their top. But as you can see the existing wall is sloped so I need to rise the sloped part to the top 4.5 meters height, represented by the dotted lines

Here is an elevation view

http://files.engineering.com/getfile.aspx?folder=8925dc78-05f5-488e-8756-ebdbd4d8e79a&file=Ret.png

Hope these details clarify the situation.

 

[fcu45]

I thought of having the first half of the sloped walls to be extended to the top as load bearing, while the lower level second half to be having columns connected by top beam that will carry the roof HCS.

But what would be the best way to connect the existing structure to the required extension?
Thanks

 

[hokie66]

Provided the pile footings are adequate, and I imagine they are, I would lean toward providing a new row of columns just inside the wall for the entire length, with a continuous cast in place beam to receive the precast slabs. Then the triangular part above the existing concrete wall can be filled in with lightweight framing and cladding.

 

[fcu45]

Thanks Hokie66

That solution can simplify things, but the retaining walls would be lost although they are sufficiently reinforced and can easily carry such small loads.

But how would you suggest to plant/connect these columns to the pile cap? Looks like steel columns can help here (But I am not sure if they can cut and place the needed anchor bolts on the outer side).

I was thinking that the sloped walls can be utilized as load bearing wall for half of that 60 meter length.

 

[BAretired]

I like hokie's suggestion. Columns could be anchored to top of footing using drilled Hilti anchors. The columns could be laterally attached to the retaining walls to resist wind loads on the future building.

This avoids the problem of creating a moment connection at the top of the sloping walls.

BA

 

[hokie66]

Yes, as BA says, connecting the new columns to the existing structure by drilling in anchors is simple. You aren't wasting the wall, as it will still form part of the enclosure. Avoiding the complication of connecting to the sloping wall makes sense to me, and I think most contractors would agree.