Back4.1.8.9.(2)

ATTRIBUTION:

Functional Statement:

F20

To support and withstand expected loads and forces.

Objective:

OS2.1

 

APPLICATION:

Overstrength-related force modification factor, Ro, to be used with a particular ductility-related force modification factor, Rd, applicable to the building structure, to be used in calculating the base lateral earthquake force, V, in Sentence 4.1.8.11.(2), and the base lateral earthquake force (dynamic analysis), Vd, in Sentence 4.1.8.12.(5).
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 overstrength-related force modification factor used will not be appropriate for the ductility-related force modification factor, which will not reflect the correct product of RdRo as the property of the Seismic Force Resisting System, which could lead to structural failure, which could lead to harm to persons.

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:

Overstrength-related force modification factor, Ro, to be used with a particular ductility-related force modification factor, Rd, applicable to the building structure, to be used in calculating the base lateral earthquake force, V, in Sentence 4.1.8.11.(2), and the base lateral earthquake force (dynamic analysis), Vd, in Sentence 4.1.8.12.(5).
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 overstrength related force modification factor used will not be appropriate for the ductility related force modification factor, which will not reflect that the product RdRo is a property of the Seismic Force Resisting System, 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.