Step-by-Step Procedure for Finding the Seismic Design Category of a Structure

May 15, 2017 Abdul Siraj, P.E.

The first step is to identify the risk category of the structure per International Building Code (IBC 2012), Section 1604.5.

 

The second step is to determine the mapped maximum considered earthquake spectral response  acceleration for short periods, SS, from International Building Code (IBC 2012), Figure 1613.3.1(1).

 

The third step is to determine the mapped maximum considered earthquake spectral response  acceleration for a 1-second period, S1, from International Building Code (IBC 2012), Figure 1613.3.1(2).

 

The fourth step is to determine the site class based on the soil profile name and properties of soil in accordance with Chapter 20 of ASCE 7-10.

 

The fifth step is to use International Building Code (IBC 2012), Table 1613.3.1(1) to determine the site coefficient, Fa, related to the mapped maximum considered earthquake spectral response acceleration for short periods, SS.

 

The sixth step is to use International Building Code (IBC 2012), Table 1613.3.1(2) to determine the site coefficient, Fv, related to the mapped maximum considered earthquake spectral response  acceleration for a 1-second period, S1.

 

The seventh step is to compute the mapped maximum considered earthquake spectral response acceleration for short periods adjusted for site class effect, SMS. It is equal to the product of Fa and SS.

 

The eighth step is to compute the mapped maximum considered earthquake spectral response acceleration for 1-second period adjusted for site class effect, SM1. It is equal to the product of Fv and S1.

 

The ninth step is to calculate the design spectral response acceleration coefficient for short periods, SDS. It is equal to two-thirds times the the mapped maximum considered earthquake spectral response acceleration for short periods adjusted for site class effect, SMS.

 

The tenth step is to calculate the design spectral response acceleration coefficient for a 1-second period, SD1. It is equal to two-thirds times the mapped maximum considered earthquake spectral response acceleration for 1-second period adjusted for site class effect, SM1.

 

The last step is to determine the seismic design category of the structure with the aid of Tables 1613.3.5(1) and 1613.3.5(2) of International Building Code (IBC 2012).