Why is the mass participation ratio considered for the first three modes in structural analysis using ETABS, and is it mandatory?

Question

Accepted Answer

The Mass participation ratio for the first three modes is considered for structural analysis using ETABS to ensure accurate representation of the structure's dynamic behavior.

The Mass participation ratio helps in understanding how much each mode contributes to the overall dynamic response of the structure.
It is important to consider the first three modes as they typically represent the most significant modes of vibration for a structure.
By analyzing the Mass participation ratio, engineers can identify critical modes that may govern the dynamic behavior of the structure.
Neglecting to consider the Mass participation ratio for the first three modes may result in inaccurate dynamic analysis and design decisions.