Health assessment of existing infrastructure just after an earthquake is a very important but challenging task. Even engineered structures can suffer significant damage(s) due to seismic excitation. To ensure public safety and to maintain economic activities of the surrounding communities, structural health needs to be assessed promptly following the earthquake. Two novel structural health assessment procedures are under development at the University of Arizona. They are known as Modified Iterative Least-Squares with Unknown Input (MILS-UI) and Generalized Iterative Least-Squares Extended Kalman Filter with Unknown Input (GILS-EKF-UI) techniques. These procedures are finite element based time domain system identification (SI) techniques and capable of identifying structures at the element level using only dynamic response information. These procedures were extensively verified using numerically simulated and laboratory measured response information obtained for defect-free and defective frames under sinusoidal and impulsive excitations applied in the super-structure. Health assessment of the same defect-free and defective frames using numerically simulated response information under seismic excitation is presented here.