Structural System

Vertical Seismic Resistance System

Response Modification Factor (R)

Bearing Wall System:
A structural system with bearing walls providing support for all, or major portions of, the vertical loads. Seismic force resistance is provided by shear walls or braced frames.

Reinforced Concrete Shear Wall

3.0

Reinforced Concrete Shear Wall supported by boundary elements in both ends

3.5

Moment Resisting Frame System:
A structural system with an essentially complete Space Frame providing support for vertical loads. Seismic force resistance is provided by Ductile or Ordinary Moment Resisting Frames

Ductile
Moment Resisting Frame

Reinforced Concrete

5.0

Steel

6.0

Ordinary
Moment Resisting Frame

Reinforced Concrete

3.5

Steel

4.5

Dual System:
A Ductile Moment Resisting Frame shall provide which shall capable of resisting at least 25% of the prescribed seismic forces. Total seismic force resistance is provided by the combination of the Ductile Moment Resisting Frame and shear walls or braced frame in proportion to their relative rigidities.

Reinforced Concrete Shear Wall and Steel Ductile Moment Resisting Frame

6.0

Reinforced Concrete Shear Wall and Reinforced Concrete Ductile Moment Resisting Frame

5.5

Steel Braced Frame and Ductile Moment Resisting Frame

4.5

Building Frame System:
A structural system with an essentially complete Space Frame providing support for vertical loads. Seismic force resistance is provided by shear walls or braced frames.

Reinforced Concrete Shear Wall

4.0

Braced Frame

3.5

Vertical Cantilever Type Structural System:
(elevated water tank, control tower, observatory, silos, chimneys steel tower etc.)

1.5

Undefined System

3.0