importance of local ground class

[kübra]

Hello, I'm reviewing a project. In the project, the calculation was made by taking the local soil class Z3. However, it is specified as Z2 in the ground survey report. How does this affect the structure? I know that the loads acting on the floors are more in the Z3 class. So it has been a safer solution. Am I thinking wrong?

 

[erbil]

Local soil classes are an effective factor in determining the earthquake load that will affect the structure. It also allows you to have an idea of whether your structure remains in the resonance range.