The document discusses response modification factor (R factor), which accounts for ductility, overstrength, and redundancy in seismic design. It outlines the evolution of seismic codes from 1906 to present day, including key studies. R factor values have increased over time as codes recognized structures' ability to dissipate energy through inelastic behavior. The document also provides methods for calculating R factors based on strength and redundancy, and compares R factor values assigned by different modern codes to structural systems like braced frames, shear walls, and composite systems.

1. Response Modification
Factor

2. • Introduction
• Response Modification
Factor
• Ductility
• Overstrength
• Redundancy
• Evolution of Seismic Codes and Response Modification Factor

3. • Evolution of Seismic Codes and Response
Modification Factor
The Great San Francisco Earthquake of 1906
1931 1927
1959 1978

6. • Newmark and Hall (1982)

7. I. Using nonlinear static analysis to construct the base shear–roof
displacement relationship for the building.
II.Calculating the base shear force (𝑉0) in the building at the roof
displacement corresponding to the limiting state of response. The
reserve strength is equal to the difference between design base shear
(𝑉𝑑) and 𝑉0.
III. Calculating strength factor by using the following expression:
𝑅𝑆 =
V0
Vd
• Strength
factor:

8. • Redundancy
factor: Line of vertical seismic framing Redundancy factor 𝑅𝑅
2 0.71
3 0.86
4 1.00

9. Determination of
R Factor

10. Str. Sys. Code
ASCE 7-10 ECP 201 IBC 2003
Steel eccentrically braced frames 8 7 7-8
Steel special plate shear walls 7 6 6
Ordinary reinforced concrete shear
walls
5 4.5 5
Steel and concrete composite
ordinary braced frames
3 - 3-3.5
Ordinary precast shear walls 4 3.5 4
Fig. shows the value of response modification factor R due to different code of loading