The design base shear is calculated using the formula:

where

V	=	minimum lateral seismic force at the base of the structure, to be used with a load factor of αe = 1.0
Ve	=	equivalent lateral force at the base of the structure representing elastic response.
U	=	Factor for Representing level of protection based on experience - always 0.6
R	=	Force Modification Factor - Given in table 4.1.9.1.B

The building period is calculated using either Method A or Method B. The formulaT = 0.085(h_n)^3/4 for SMRF, or T = 0.075(h_n)^3/4 for concrete moment frames is referred to as "Method A" by RAM Frame. Method B, on the other hand, involves carrying out eigenvalue analysis to determine the building fundamental periods.

For torsional moment provisions, the two most critical separate load cases are generated in both X and Y directions from the code-specified loads shown below:

• T_x = F_x(1.5e_x + 0.1D_nx)
• T_x = F_x(1.5e_x - 0.1D_nx)
• T_x = F_x(0.5e_x + 0.1D_nx)
• T_x = F_x(0.5e_x - 0.1D_nx)

For dynamics procedures, users must run both static force procedure and dynamic load cases (response spectra, for instance) and add the code-specified additional loads in the Analysis - Load Combinations Mode.

RAM Frame has also implemented the code requirement for increasing the Base Shear by 50% in velocity-related seismic zones of 4 and higher for buildings of more than 60 meter height with a structural system having R = 2.0 or R = 1.5.