trench concrete detail 1

[Jandra11]

is there a possibility not to put any reinforcement on the concrete considering the concrete can withstand the load itself? any advise and comments are very much welcome. thank you.

 

[Jandra11]

Thank you guys for all the response. btw I found some loading on aashto 6th:2012 saying that vehicular live load should have the combination of design truck/design tandem and design lane load.

 

[TehMightyEngineer]

That's for bridges. Nobody designs small buried trenches for tandem loads as it never controls over the HL-93 (essentially the same as an H20) load. Heck I rarely design FAA manholes for more than one wheel load on a large aircraft landing gear; you just can't fit that many wheel loads on a small, buried structure. Buried structures are also exempt from lane loads according to AASHTO and the various ASTM standards covering precast buried utilities, which makes sense as it's a bridge load for long lines of traffic.

Seriously, just listen to TLHS and myself. Don't reinvent the wheel. It's fine if you want to look over the design of the supplier of the trench (I encourage it, even) but realistically most precasters and trench grating suppliers will have this figured out already.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[DenverStruct]

For a small trench like that, more than likely 16k wheel load on top of structure will not control anything (the bending of the bottom slab will be minimal because only 1 ft span). For small trench like this, you probably only use 1 layer of rebar 2" from exterior wall and right in the middle of the bottom slab. Design the steel for 80 PSF live load surcharge (per AASHTO), plus the horizontal soil pressure.

 

[Jandra11]

thank you guys.Even I dont know the reason why would a trench should consider those loading. when I first made the calculation i just consider soil pressure + surcharge from the sidewalk load. and then their asking that loading should follow aashto provisions.
BTW thank you all.