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Concrete Stage/load Capacity

Concrete Stage/load Capacity

Concrete Stage/load Capacity

(OP)
I have been asked to research the following: Laying a concrete "pad" on an existing amphitheater "stage" that is really made up of decomposed granite that they cover with temporary sub floors panels. The area is approx 50' wide by 50' deep. I need this area to have a permanent concrete stage. I also want/need the stage to have footings that support a temporary truss/load bearing truss structure where I want to load both lighting and a speaker system on motors. Of the MANY things I need to figure out, the main one is 1) what type of concrete 2) what is the load bearing capacity of a concrete slab and can/should the footings to support this weight be different that the bulk of the concrete that would be laid out for the larger footprint.

RE: Concrete Stage/load Capacity

Contact & engage a local structural engineer.

They will either be familiar with the area and specify the appropriately sized footings, or do a soil bearing investigation to determine the actual on-site requirements.

RE: Concrete Stage/load Capacity

Agree with Signious. The slab on ground is not a safety concern, but the supports for the performance systems certainly are.

RE: Concrete Stage/load Capacity

(OP)
Thanks and yes there is no way that this project will get implemented without a certified engineer, but while I collect information on this to pitch the concept to the "bosses" I need to get some type of detail laid out. Is there a formula to figure out a compressive strength/spacing of rebar and thickness of concrete for towers and truss that will need to support 4000 pounds?

RE: Concrete Stage/load Capacity

Sage,

Yes, and if you spend about 4 years in school, 4 years working as an EIT, sit for an 8 to 16 hour exam you will know the answer. I don't say this to be harsh, but to say that structural engineering isn't something you pick up from a message board online. It's extremely involved and is not something that you can just jump into. For example, let's say you design a beam for bending (flexure) and it works perfectly and so you think you are OK and then it fails. Turns out shear controlled the design but you didn't know that because you didn't know what shear design was. I've had people think 4000 psi concrete means that they can put 4000 lbs per square inch on an elevated slab. While I don't know how you could physically do that over a large area, they certainly didn't know the concept of concrete strength.

Again, this isn't a knock on you at all, but trust Signious and hokie and hire an engineer. They can help you in the early stages and the late stages.

Nick

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