To limit the probability that the design base shear for the structural analysis of the building will not take into account all the factors that affect the expected magnitude and distribution of seismic forces and displacements in the building structure, which could lead to structural failure, which could lead to harm to persons.
To limit the probability that the calculation of loads due to earthquake loads will not take into account how the expected fundamental lateral period of the building structure affects the seismic forces and displacements in the structure due to the seismic ground motions, which could lead to structural failure, which could lead to harm to persons.
To limit the probability that the calculation of loads due to earthquake loads will not take into account the properties of the structural system [i.e. lack of ductility, energy absorption and overstrength], which could lead to structural failure, which could lead to harm to persons.
To limit the probability that the lateral-force-resisting system chosen for the design will not have a minimum ductility and integrity to absorb local failure due to maximum expected seismic ground motions, which could lead to structural failure, which could lead to harm to persons.