The Criteria – Redundancy Factors command is used to specify the various quantities needed to calculate the redundancy factors, rho, corresponding to seismic load cases.

There is a special allowance for structural systems that are considered Dual Systems. If a structural system is a Dual System it should be so specified. Considering the building as a dual system in X or Y direction will enable using a 0.8 reduction factor on the redundancy factors.

"A _B " is the ground floor area, defined either by specifying the diaphragm from the pull-down menu whose area will be taken as that corresponding to "A _B " or explicitly by entering the floor area in the appropriate units.

A column that is an interior column of a multi-bay frame is treated differently than the end columns. The program automatically accounts for that. When frames are skewed between one bay and the adjacent bay, it is necessary for the user to indicate the angle between bays at which the common column can still be considered an interior column.