Which one of the following statements is not correct regarding the response reduction factor ?
- AIt accounts for inherent system ductility.
- BIt accounts for redundancy.
- CIt influences the non-linear behaviour of a building during strong earthquake shaking.
- DIt accounts for the importance of the building.Correct
Solution
Concept
Response reduction factor (R) versus importance factor (I)
Formula
Design horizontal coefficient Ah = (Z/2)(I/R)(Sa/g)
Step-by-step solution
1. R reflects ductility, redundancy and overstrength of the lateral load resisting system. 2. The importance of the building is accounted for by a separate factor I (importance factor). 3. So statement (d) is incorrect.
Explanation
In Ah = (Z/2)(I/R)(Sa/g), the importance of the building appears as I, while R covers ductility, redundancy and overstrength. They are independent factors.
Why the other options are wrong
Statements (a), (b) and (c) correctly describe what R represents.
Shortcut
R = ductility + redundancy + overstrength. I = importance.
Common mistake
Thinking R depends on the building use.
Correct answer: D) It accounts for the importance of the building.