§ 27-718 Factor of safety.
AC § 27-718
(a)Overturning. The minimum factor of safety against overturning of the structure as a whole shall be one and one-half. Stability against overturning shall be provided by the dead load of the building, by the allowable uplift capacity of piling, by anchors, by the weight of soil directly overlying footings provided that such soil cannot be excavated without recourse to major modification of the building, or by any combination of these factors.
(b)Sliding. The minimum factor of safety against sliding of the structure under lateral load shall be one and one-half. Resistance to lateral loads shall be provided by friction between the foundation and the underlying soil, by passive earth pressure, by batter piles, or by plumb piles, subject to the following: (1) The resistance to lateral loads due to passive earth pressure shall be discounted where the abutting soil could be removed inadvertently, by excavation.
(2)In the case of pile supported structures, frictional resistance between the foundation and the underlying soil shall be discounted.
(3)The available resistance to friction between the foundation and the underlying soil shall be predicated on an assumed friction factor of one-half for soils of classes 1-65 through 8-65. A greater value of coefficient of friction may be used subject to verification by analysis and test. For soils of poorer classes, the stability shall be analyzed by accepted procedures of soil mechanics.
