LRFD Empirical Deck Design

[heyrooman]

One of the provisions for using the empirical design is that the overhang beyond the centerline of the outside girder is 5.0 times the depth of the slab or 3.0 times the depth of the slab and a structurally continuous barrier rail is made composite with the overhang. The barrier rails that will be used are composite with the deck, but they are built in 6m segments with an open joint between the segments. Is this considered to be structurally continuous?

 

[wiktor]

Foe the deck design you can assume that the barrier is continuous, as the deck's edge stiffening will be not highly affected by the joints spaced at 6 m, and the overhang limited to 1.75 m

 

[bridgedude]

The requirement for the overhang is to brace the exterior girder in the lateral direction. The empirical method is based on arching action in the deck. If the exterior girder "kicks out" the arch will not function properly. You must be careful in considering barrier continuous if there are open joints in the barrier, since that reduces the lateral bending stiffness of the composite deck/barrier at that point.
If you do not have the proper lateral restraint for the exterior beam to have arching action, you should design the deck by some other method.

 

[curvbridger]

It is NOT structurally continuous. Ask your client to consider changing to continuous barrier with stress-relief sawcuts or v-grooves. A continuous barrier reduces deflections, increases reserve strentgh, and has a proven history. Also, reinforcing the barrier at each open joint requires much more steel - see Equations A13.3.1-1 and A13.3.1-3 in the 1998 code

curvbridger