Where the effects of the seismic ground motion and gravity loads are additive, seismic load,

*E*, for use in Equation 16-19, shall be defined by Equation 16-52.

_{m}
Em=

*ΩQ*+ 0.2_{E}*S*_{DS}D**(Equation 16-52)**Where the effects of the seismic ground and gravity loads counteract, seismic load,

*E*, for use in Equation 16-20, shall be defined by Equation 16-53.

_{m}
Em=

*ΩQ*- 0.2_{E}*S*_{DS}D**(Equation 16-53)**where

*E*,

*Q*,

_{E}*are as defined above and Ω*

_{SDS}*is the system over strength factor as given in Table 1617.6.2.*

_{0}The term

*need not exceed the maximum force that can be transferred to the element by the other elements of the lateral-force-resisting system.*

_{0}Q_{E}Where allowable stress design methodologies are used with the special load combinations of Section 1605.4, design strengths are permitted to be determined using an allowable stress increase of 1.7 and a resistance factor, f, of 1.0. This increase shall not be combined with increases in allowable stresses or load combination reductions otherwise permitted by this code or the material reference standard except that combination with the duration of load increases in Chapter 23 is permitted.