Bridge_Man
Structural
- Apr 2, 2020
- 42
Hi,
I don't deal much with prestressed concrete bridges and here is my question.
I have 2 span bridge, simply supported until the deck comes in. Composite loads including LL will act on the composite section. Am using Leap concrete or open bridge designer (whatever you want to call it) for the design. The software similar to many samples I've seen online some from FHWA considers the deck effective for computations of composite properties for service load combinations. in both -ve and +ve moment regions. So stresses in the girder due to composite loads and LL over the pier are using the composite properties assuming the deck is fully effective for service III, which we don't usually do for steel strength design.
I know AASHTO permits this for steel Service II load combo as long as the deck has at least 1% steel not exceeding #6 size since it will control cracks and will still be considered effective. but I couldn't find anything that talks about this topic in specific for prestressed concrete beams. do you know of a clause that backs this up?
I am providing more than 1% in my deck since am designing it to take the full -ve moment in strength (AASHTO requirement), but I also checked rupture stress and I think am slightly over it. so I just want to make sure LEAP and me are not missing anything.
Thanks!
I don't deal much with prestressed concrete bridges and here is my question.
I have 2 span bridge, simply supported until the deck comes in. Composite loads including LL will act on the composite section. Am using Leap concrete or open bridge designer (whatever you want to call it) for the design. The software similar to many samples I've seen online some from FHWA considers the deck effective for computations of composite properties for service load combinations. in both -ve and +ve moment regions. So stresses in the girder due to composite loads and LL over the pier are using the composite properties assuming the deck is fully effective for service III, which we don't usually do for steel strength design.
I know AASHTO permits this for steel Service II load combo as long as the deck has at least 1% steel not exceeding #6 size since it will control cracks and will still be considered effective. but I couldn't find anything that talks about this topic in specific for prestressed concrete beams. do you know of a clause that backs this up?
I am providing more than 1% in my deck since am designing it to take the full -ve moment in strength (AASHTO requirement), but I also checked rupture stress and I think am slightly over it. so I just want to make sure LEAP and me are not missing anything.
Thanks!
