Dam engineering design / mass concrete design

[rharashi]

I previously posted this under the Structural forum and it appears to have been removed. If you had responded to that thread, please respond here as well since I very much need an answer to this question.

I have been asked to determine the number of 5' lifts that will be required on a concrete headwall that spans across the opening for a tainter gate on a new dam. Specifically, I need to calculate how many lifts need to be in place before the shoring can be removed. The lifts would need to support their own weight as well as the weight of the next 5' lift when poured. I also will need to determine what load the shoring will need to be capable of carrying.

Does anyone know what codes would be applicable to this design. There is very little reinforcing in the headwall and all that there is is located in the first two lifts. The first lift has reinforcing in the skin. The first and second lifts also have reinforcing in the top of the pour that is embedded in the dam piers. This reinforcing does not run the entire span, but rather ends at a distance of 8' from the each pier. The headwall spans 24', so the middle 8' does not have any reinforcing in the tops of these two lifts.

I really appreciate any feedback the community might have.

 

[msquared48]

The ACI has a forming design manual that will give you the information you need. Check on their website and order it.

Mike McCann
MMC Engineering

 

[rharashi]

Thanks msquared48,

Will the forming manual deal with the question of the number of required lifts before the shoring can be removed? In other words, I need to analyze the headwall as a largely non-reinforced mass concrete beam. I would imagine that after the beam is thick enough, it would act mostly in shear and the rebar would not be important.

Thanks