Back4.1.8.11.(5)

ATTRIBUTION:

Functional Statement:

F20

To support and withstand expected loads and forces.

Objective:

OS2.1

 

APPLICATION:

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.

INTENT:

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.

ATTRIBUTION:

Functional Statement:

F20

To support and withstand expected loads and forces.

F22

To limit movement under expected loads and forces.

Objective:

OP2.1, OP2.4

 

APPLICATION:

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.

INTENT:

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.