90 ft x 29 ft typical bay - what are my options with concrete? 1

[wayren]

The project, at its schematic design phase, is a one-story (30' floor to roof) roofed bus maintenance facility that requires a 3hr fire rating. Concrete, therefore, was selected as the construction material. The roof of this structure is open deck parking.

Here are some of the typical bay sizes
65 ft x 40 ft - layout - 1x65'(N-S) and 13x40'(E-W)
45 ft x 40 ft - layout - 5x45'(N-S) and 13x40'(E-W)
90 ft x 40 ft - layout - 1x90'(N-S) and 13x40'(E-W)

Right now, I am considering precast prestressed member with topping (I-beams and hollow core or double tee) - worry about water infiltration at the joints between precast members and future maintenance cost for those joints. Comments?

Cast-in-place post-tensioned construction is considered but I have no experience with it. I have started gather references from PTI. Any recommendation?

I am planning to use non-prestressed concrete beam for the 45ft span and span the 40' with 12" hollow core with 2" topping. Any comments?

I have not decided what to do with the 65' and 90' span.

Any advice/comments will be helpful. Thanks

 

[dougantholz]

most parking garages operate on a 60 to 65 ft clear span, so un-topped double tee's would probably be the most economical in concrete. Make sure that you tell the p/c company about the extra cover you will need.

 

[Lion06]

If you are considering using PC/PS double T's, why not consider PC/PS Girders instead of CIP. They behave better for deflections. I don't know how they compare in cost, but......