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Trench drain over grade beam.

Trench drain over grade beam.

Trench drain over grade beam.

I have a foundation on void forms that is a one-way slab system, rated for HS-20 loading. There are grade beams supporting the slab that coincide with 8" deep trench drains running parallel to and centered on the beam line. In order to keep slab continuity, I am bending the top slab steel down below the drain at a 1:6 slope and deepening the slab under the bent portion the same depth of the drain. I am also providing hooked dowels at the lower bend to resist the uplift force created by the offset of the steel. I have attached a detail showing what I am describing. I chose to step the bottom of the slab instead of sloping it because a rep once informed my that the system works better with stepping it, but I'm not sure if I need to include any additional steel in the dropped portion since it should always be in compression. I have attached detail of what I am showing, if anyone could take a look at it and let me know if I am missing or overlooking something that would be great.

RE: Trench drain over grade beam.

I'm not a structural engineer in practice, but this needs shear resistance at the support.

RE: Trench drain over grade beam.

Is it possible to move the grade beam or the trench drain? Your bent sloped bars do very little and you should look at alternative reinforcing. If the trench must remain, can you construct two grade beams, one on each side of the trench with a concrete 'fill in' below the trench. You can simply add stirrups tying the two parts together. Your slab appears to be 10" thick... is this correct?


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