Vertical Shear & LRFD Rating Factors

Hello,

I am load rating a bridge using LRFD 8th Ed, with "Flared" and Girder-by-Girder analysis ticked on so that CONSPAN can properly calculate the beam lengths for a span with a perpendicular pier and a skewed pier:

We have been trying to figure out why there is such a large discrepancy in the shear rating factors for Inventory vs Operating. Per MBE C6A.1.1, "The operating rating factor is determined by multiplying the inventory rating by the ratio of the inventory live load factor (1.75) to the operating level live load factor (1.35)". This equates to roughly RFop = 1.3 x RFinv. We are using Beta-Theta Equations for shear.

I have checked the "Vertical/Horizontal Shear" output and have personally calculated strain, Beta, Theta, and Vc to within 5% of what is in the table based on other variables provided in the table at 0.8L (the controlling location for beam 2).

The only variable I do not know where to find is Nu. Assuming Nu = 0, I am calculating pVn = 149.668 kips which would yield Inventory/Operating rating factors of 1.07/1.39, respectively using DC = 23k and LL+I = 64.3k from "Shear/Moment Envelope (&Reactions)" tab. Assuming a pVn/Vu ratio of 0.875 and a Vu of 141.3k from the image above, this would yield a pVn of 123.6375k which in turn would yield Inventory/Operating rating factors of 0.84/1.09).

The issue is CONSPAN is reporting shear RFs of 0.88 & 1.70 for Inventory and Operating. How can this be?


I have made test models with "Flared" without Girder-by-Girder analysis" and also a non-skewed model where all beams are of the same length with the same shear reinforcement as beam 2 and still get a drastically greater ratio than 1.3 for Operating over Inventory.

Can you please provide reasoning for such a high Operating shear Rating Factor?