Dear Bush,

The response reduction factor (R) is a term used in seismic design codes to account for the inherent uncertainty and variability in the behavior of a structure during an earthquake. R is used to reduce the seismic design forces used in the design of the lateral resisting systems (e.g., walls, shear walls, diaphragms, etc.) to account for the uncertainties in the actual seismic performance of the structure.

The value of R is typically calculated using probabilistic or deterministic methods based on the results of seismic hazard analysis, seismic ground motion simulations, and empirical data on the performance of similar structures in past earthquakes. The specific method used to calculate R will depend on the seismic design code and the type of lateral resisting system being analyzed.

In some codes, the value of R is provided as a prescriptive value in tables or equations. In contrast, in other regulations, the engineer must perform a more detailed analysis to determine the appropriate value of R based on the specific site conditions and seismic hazards.

Overall, the value of R is an essential consideration in seismic design as it helps to ensure that structures are designed to a reasonable and consistent performance level with available data on seismic hazards and seismic performance.

Let's consider a building in a moderate seismic zone with a shear wall lateral resisting system. According to the seismic design code, the response reduction factor (R) value for this type of lateral resisting system is R=3.

This means that the seismic design forces used in the design of the shear wall must be multiplied by a factor of 3 to account for the inherent uncertainty and variability in the actual seismic performance of the structure. So, if the calculated design seismic force for the shear wall is Fd, the real design force that must be used in the design calculations would be R * Fd = 3 * Fd.

In this example, the value of R helps to ensure that the shear wall is designed to withstand a level of seismic force appropriate for the site's specific seismic hazard while also accounting for the inherent uncertainties in the actual seismic performance of the structure.

Yours sincerely,

Edgar M Cambaza

Thank you so much sir

🙏🙏

I suppose the following article:

(PDF) The Pushover Analysis in its Simplicity (researchgate.net)

http://www.researchgate.net/publication/323607343_The_Pushover_Analysis_in_its_Simplicity

should be able to give you some clarity on this.