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StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 6689
Experience:  Structural Engineer
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I'm building a basketball court that is sunken into the

Customer Question

Hi, I'm building a basketball court that is sunken into the ground due to a sloping back yard. On 2 sides of the court slab the dirt is 3ft high and the contractor built forms on 1 side and the other side is a dirt wall that was basically carved out when they dug the area. Essentially he is going to pour concrete between the form and the cut out earth. The earth wall is really hard because we have clay soil so it is not soft or loose. The retaining wall will be 3ft high, 8" wide, has #5 rebar going horizontal and #3 vertically. The wall is not cantilever but when they pour concrete for the slab (bball court) they will also pour the walls so everything will be one massive concrete structure. I don't want it to cave in on me in a few years so is this enough to hold the dirt back? I live in Dallas and we have clay soil which is hard as a rock but when wet expands. They did not dig a footer under the wall because technically the slab will be the footer. Also no beams or piers used just rebar and then they will pour concrete. Please help!! Thank you
Submitted: 1 year ago.
Category: Structural Engineering
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 1 year ago.
Customer: replied 1 year ago.
wall 2
Customer: replied 1 year ago.
Expert:  StructuralEng replied 1 year ago.

Hello. How are you doing? I'll be happy to assist you.

Customer: replied 1 year ago.
Hi, did you review my question? I'm new to this site and submitted pictures and my project that i need help with but don't see a response from you other than you can help me.
Expert:  StructuralEng replied 1 year ago.

I'm looking at your pictures

Expert:  StructuralEng replied 1 year ago.

How thick is the slab and is it reinforced?

Customer: replied 1 year ago.
4" slab and rebar 16" on center throughout like you see in the picture. The retaining wall will be part of the slab since it's all being poured at once. Can 1 side of the retaining wall just be poured up against the dirt like you see in the 1 picture? Usually I've seen 2 forms forming a cavity to pour the concrete and then backfill with dirt but here they're pouring right up to the dirt so no backfill needed, not sure if that's good or bad for the strength or structure of the wall. It's only holding back 3 ft high of dirt but over time can the pressure cause damage the way it's being built? Thanks!
Expert:  StructuralEng replied 1 year ago.

I would not let an 8" wall cantilever up off a 4" slab.

Customer: replied 1 year ago.
Its not a cantilever wall they're building just a straight vertical wall. What do you recommend? And do you have answers to the other questions about pouring concrete up against the pure earth?
Expert:  StructuralEng replied 1 year ago.

That is a cantilevered wall. It's a vertical cantilever off the 4" slab.

Concrete is poured against earth all the time. It just requires additional clear cover for the rebar

Customer: replied 1 year ago.
As an engineer how would you build the wall for my scenario? And isnt cantilever thinner on top and wider on bottom instead of even all throughout?
Expert:  StructuralEng replied 1 year ago.

It's the way it resists loads (as a cantilever) that makes it a cantilever, not a tapered profile. I would build it as a cantilever, but with a properly sized footing that is independent of the court

Customer: replied 1 year ago.
Why can't the slab serve as a good base with all the rebar in it? Im trying to figure out what needs to change from the current design.
Expert:  StructuralEng replied 1 year ago.

Because it only has a thickness of 4". The moment capacity of the slab is not even close to the moment capacity of the wall, so it doesn't even make qualitative sense. It's supporting a bending moment, not just the vertical load.

Expert:  StructuralEng replied 1 year ago.

Hello, do you have any other questions for me on this topic? If you could rate my answer, I would appreciate it.

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