There are 2 main principles used in AISC 360-16
Allowable Strength Design - AISC 360-16 ASD
Load Resistance Factor Design - AISC 360-16 LRFD
The regulations specify the increment of loads that act into the structure with certain coefficients and decrease the structural members' capacity with certain coefficients. Different loads (uniform, concentrated, live, snow, wind, earthquake, etc.) are multiplied by the coefficients for the cases when the load computation is done incompletely. The capacity of the member is determined according to the cross-section and material properties, which is reduced by certain coefficients in order to take into account the deviations in material properties, manufacturing defects, etc.