Overturning effects at the soil–foundation interface are permitted to be reduced by 10% for foundations of structures designed in accordance with the modal analysis requirements of Section 12.9.
The nominal foundation geotechnical capacity, Qns described in 12.13.5.1, is controlled by the user. It's taken into geotechnical report by users.
The resistance factors (ϕ) is controlled by the user.
Reduction of Foundation Overturning
Overturning effects at the soil–foundation interface are permitted to be reduced by 10% for foundations of structures designed by the modal analysis requirements of Section 12.9.
Strength Design for Foundation Geotechnical Capacity
Where basic combinations for strength design listed in Chapter 2 are used, combinations that include earthquake loads, E, are permitted to include reduction of foundation overturning effects defined in Section 12.13.4.
The nominal foundation geotechnical capacity, Qns, described in 12.13.5.1, is controlled by the user.
Resistance Factors
The resistance factors are used for all foundation types' vertical, lateral, and rocking resistance. Nominal foundation geotechnical capacities, Qns, are multiplied by the resistance factors (ϕ) shown in Table 12.13-1.
Acceptance Criteria
For linear seismic analysis procedures, factored loads should not exceed foundation design strengths, ϕ*Qns.
Foundation Design
Foundations are designed to support gravity and design earthquake loads, as indicated in the basic load combinations of Section 12.4, using the reduced soil bearing capacity, as shown in the geotechnical investigation report, considering the effects of liquefaction caused by MCEG earthquake motions.