I believe that you need more reinforcement.
Adding a wire mesh over the planned re-bar, would be better.
Have you did the calculation of the weight of this ?
There is tons of force on the center, and concrete has lots of compression strength, but is surprisingly weak in the tensile stretching area.
Commercial pre-stressed things are just that, they stretch the reinforcement, then pour the slab, and wait for curing, then release the reinforcement tension, which pulls the thing together tightly.
Think about installing I beams, or RR track, from pier to pier, as a support for your design.
ED
Adding a wire mesh over the planned re-bar, would be better.
Have you did the calculation of the weight of this ?
There is tons of force on the center, and concrete has lots of compression strength, but is surprisingly weak in the tensile stretching area.
Commercial pre-stressed things are just that, they stretch the reinforcement, then pour the slab, and wait for curing, then release the reinforcement tension, which pulls the thing together tightly.
Think about installing I beams, or RR track, from pier to pier, as a support for your design.
ED