Hi,

Im doing Rafter design in TANK, Software is calculating

User Specified Design Roof Load .......(KPa ): 1.6619
(including user plate thickness)
Computed Design Roof Load .............(KPa ): 1.6619
(including user plate thickness)

AS per API 5.2.2 load combination

Total Design External Pressure Loading per V.7 [Pr]:
= max[ DL + (Lr or S) + 0.4Pe, DL + Pe + 0.4(Lr or S)]
= max[ 9.647 + max[25.063 , 0.000 ] + 0.4 * 0.000 ,
9.647 + 0.000 + 0.4 * max[25.063 , 0.000 ]]
= max[ 34.709 , 19.672 ]
= 34.709 psf [1661.893 N/M2]

DL value is 9.647 psf

For Rafter design , DL dead load is Rafter wight plus Roof weight,
Manually calculated DL for Rafter is 21 psf. But Software calculating DL value is 9.647 psf which is only roof load.

PLease clarify how to calculate DL for Rafter? matter very very urgent