Transverse post tensioning of adjacent p/s conc. box beam bridges

[bgarbasz]

We are performing construction services for a project on which we also performed the design. The superstructure is comprised of prestressed concrete, adjacent BI-48 box beams. Based on NJDOT specifications, the fabricator is to design and detail the transverse post tensioning rods/strands and all anchorage details. The typical detail has a 3" diameter sleeve in the beam to accommodate the transverse ties with a steel washer plate over the opening (typically 6"x6"x3/4"). We have received the calculations and for the steel washer plate the contractor calculated the required thickness to satisfy shear requirements based on the following calculation:

Shear area =Pi*3"(diameter of sleeve)^2/4 * plate thickness * sqrt(2)

My question is if bending of the plate should also be considered. Anyone have experience designing the steel washer plate for this type of bridge?

 

[shin25]

I think the shear area should be= Pi*3"*plate thickness. I have seen this kind of construction before, but for transverse P/T the contractor uses proprietory system, like Dywidag rod and standard bearing plate. These plates are about 1 3/4" to 2" in thickness. To accommodate these plates, off course there has be to block out in the exterior beams.

 

[bridgebuster]

A 6" x 6" x 1" plate should be fine.