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Thank you for your replies & links. The pipe has to go through a hill and thats why the manhole is so deep. I have checked precast calculations from manufacturers and their manholes don't work for depths below 50 ft. I also don't know if caisson would work, I've look at a lot of resources and...

Thanks for the reply. I did, no one does manholes that deep, so we have to do a cast in place. At least for the bottom 30 ft of it & they don't deal with the foundation.

Hi, I'm working on designing the walls, rebars, top and bottom slabs for a 70' deep, 8 ft diameter manhole considering H20 loading (meaning there is a minimum of 32 kips truck load on the top slab). I've never designed a structure like this and i'm wondering if there are major issues to look...

Thank you for the great answers. I ended up going with the piles as you recommended.

Thanks for the replies. I have limited real estate & can't move the building further in. Are there any specific parts of the codes I need to look at for basement design?

I'm working on designing a two story building (same as the attached sketch) & here are the conditions: - The building is 72 ft x 32 ft; - The lower level should be all concrete & waterproof, the top level is CMU with an A-frame roof; - The building is in a flood zone & the first floor will be...

Thanks for the sketch and comments SlideRuleEra. Yes, I have used 100 psf for live load and added 0.3 kips point loads for the pumps.I will do a cost estimate to see if using steel beams is going to be cheaper than columns.

Thanks for the great comments. I used 100 pcf for the live load even that seems a bit much. This project is in the middle of nowhere. Using a slab with steel beams or hollow core and skipping columns are both good ideas. However, I'm hesitant to use steel since this is going to be a very...

There isn't a rake. This is a clearwell built in 1950s for a waterplant and it's just holding water. Drilling through the existing concrete would make it difficult to seal it after, but if that's the only way then we have no choice. With pouring the new slab on top of existing one, I'm more...

Thanks... I came up with 4 columns and a 12" slab on top. The problem is the bottom slab of existing tank is only 6 inches thick. I'm worried there is not enough room for rebars to be embedded in the old concrete for a new slab to be poured on top of the old one to act as a foundation. Does...

Thank you for the replies. Actually the diameter is 44 ft not 22. I think I would probably end up with a flat slab with 3 columns. The center of the tank has openings and equipments and I won't be able to add a column there...

I'm designing a concrete cover for a 22' diameter existing concrete circular tank. The Tank is embedded in the ground and there will be people walking on top of it. Here are the conditions: - The slab on the bottom has a slope. - The depth of Tank varies from 9'-6" at the edge of the wall to...

Thanks for the replies. They are really helpful. Can I use regular epoxy rebars intead of Hiltis? The client insists of extending the basin instead of building a new one next to it. Also, the extended foot print of the foundation needs to connect to the new concrete, do you recommend Hilitis...

The rest of the wall seems to be ok, using HILTIs calculations are ok. As long as the original rebars are constructed as planned. The old basin is more than 30 years old. Do you recommend using HILTIs or regular epoxy rebars are ok too? What can I do to address the rest of the wall & lap splices?

Hi, I am working on adding another concrete tank aeration basin to an existing one. So the existing walls need to be extended. What do you recommend to consider in doweling into the old concrete? Since the tanks are going to be full, the tension in the corners add up, is simply doweling epoxy...

Thanks for the answers. This is going to be a wastewater aeration basin. So there is waste water behind the wall & it has no lateral resistance. Deflection wise it seems ok. I'm concerned about detailing of Steel, tension, and if there are any special considerations that I may be missing or if...

I'm designing a 6 ft long (from CL of the wall) concrete cantilever with no backspan on top of a 16 in wide wall. This is the first time I'm designing a concrete cantilever, can you tell me what should be considered? Should i design a simple slab? What should I consider for the rebars since...