How are MpM and MpN calculated in RAM connection?

Question

How are MpM and MpN calculated in RAM connection for base plate flexural yielding due to bearing? I am designing a column with a large moment. I am following AISC's Design Guide 1, but I cannot get my hand calculations to match the values in my RAM report. How are these calculated? Is the value of "Y" as the bearing length shown anywhere in the report? Why are these equations so cryptic!? 
 I have attached the file in questions. I am looking at the connection with uniaxial bending. By my calculations, I get Y=0.7935" and MplM=12.76kft/ft. 
 Thanks.

F_Diego · Accepted Answer

This is how we calculate the bearing moments when the bearing length is smaller than the bearing distance (this case isn’t in Design Guide 1, but we are just using basic forces equilibrium):

σ= Concrete stress= 0.3541 ksi
B= 16 in
N= 22 in
H= Bearing length= 2.7956 in
D= Bearing distance= 0.95*Depth/2= 0.95*12.1/2= 5.7475 in
M= Moment=Force*dist= (B*H*σ)(N/2-D-H/2)= (16*2.7956*0.3541)*(22/2-D-H/2)= 61.0464 kip*in
M_pM= Unitary moment= M/B=61.0464/16= 3.8154 kip*in/in

Same procedure applies for the transverse bending line MpN.