RE: Tunnel plate elements SQY for global shear

Hello,

I had a question regarding this simple circular tunnel model shown below.

I have the following modeled to check the shear SQY. I know I'm missing something simple here so I hope I can get some help.

L=100 ft (total longitudinal length)

Lpl = 1 ft (longitudinal length of each plate)

Supports: Fixed but MX MY MZ at both ends as shown above.

Load: 100 k/ft^2 applied at top half of cylinder for full length along Global -Y.

Local Coordinates:

x - along circumference

y - along longitudinal axis

z- perpendicular to plate

According to this set up summing all the SQY stresses (careful to rotate for global Y since SQY is perpendicular around circumference) should give me the global shear stress at one section. 

In doing this and comparing it to a simple V = wL/2 I find its too far off. I also take the ring close to end reaction  which I presume to be close to said reaction sum at end and find its far too low from summing QY forces. 

Here is a contour of the SQY

My question is simple, how would I go about calculating the global shear (about global Y) at a certain cut of this model? I presume I'm missing something simple so all answers welcome, thank you.