In RAM Connection, for an extended moment connection there is no load on the connection and the ratio is already 1. The failure mode is that the web fillet weld shear capacity is almost equal its axial capacity. I am wondering why the demand is not 0 as there is no load?

The imposed demands are part of the design procedure and are described in the ASI Design Guide 12 for Bolted end plate connections, even when there are no loads in the joint. For the case of the web fillet weld axial capacity, the demand is calculated as follows (excerpt taken from ASI DG 12, Sec. 9.3, page 29):

For the case of the local bending of the column flange, the demand is determined as follows (excerpt taken from ASI DG 12, Sec. 10.1, page 41)