To support and withstand expected loads and forces.

Determination of the higher mode factor, Mv,
and the associated moment reduction factor at the base of the structure, J.

This applies to *buildings* described in Sentence
1.3.3.2.(1) of Division A and to *buildings* to which Part 9 applies [see Sentence
1.3.3.3.(1) of Division A for application
of Part 9] that are required to be designed in accordance with the requirements
of Part 4.

To limit the probability that the calculation of the equivalent
static base shear will not take into account the participation of higher modes
in the dynamic response of the structure by the inclusion of the factor Mv,
which could lead to structural failure, which could lead to harm to persons.

To modify the calculation for the overturning moment at
the base of the structure, on the basis that the higher modes included in
the base shear do not contribute significantly to the base overturning moment.

To support and withstand expected loads and forces.

To limit movement under expected loads and forces.

Determination of the higher mode factor, Mv,
and the associated moment reduction factor at the base of the structure, J.

This applies to *buildings* described in Sentence
1.3.3.2.(1) of Division A and to *buildings* to which Part 9 applies [see Sentence
1.3.3.3.(1) of Division A for application
of Part 9] that are required to be designed in accordance with the requirements
of Part 4.

To limit the probability that the calculation of the equivalent
static base shear will not take into account the participation of higher modes
in the dynamic response of the structure by the inclusion of the factor Mv,
which could lead to:

- the excessive deformation of, or excessive stress in, the structural elements, which could lead to damage to the building, or
- the excessive deformation of, or excessive stress in, the building structure, which could lead to damage to the building, which could impede the intended use and occupancy of the building.

To modify the calculation for the overturning moment at
the base of the structure, on the basis that the higher modes included in
the base shear do not contribute significantly to the base overturning moment.