Abstract
A new critical excitation method is developed for a damped linear elastic structure. In contrast to the previous studies, no special constraint is needed on nonstationarity of input motions. The input energy to the structure during an earthquake is introduced as a new measure of criticality. It is shown that the formulation of the earthquake input energy in the frequency domain is essential for solving the critical excitation problem and deriving a bound on the earthquake input energy. It is also clarified that the complex modal analysis is very efficient for computation of earthquake input energy to linear elastic structures with various damping coefficient distributions and that the real eigenmodes in addition to the complex eigenmodes play an important role in the energy computation.
