90 ft x 29 ft typical bay - what are my options with concre
 

90 ft x 29 ft typical bay - what are my options with concret
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

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.
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......