“…Instead of updating an initial model, it is also possible to identify the second-order structural matrices (mass, damping, and sti ness) directly as discussed, among others, by Agbabian et al [4]; however, this methodology, as all similar equation-error approaches that are limited by the number of available sensors and=or that require numerical integration (and=or di erentiation) of available time histories, often leads to poor predictive models (Smyth and Pei [5] provide a lucid analysis of the e ects of using integrated noisy data for various system identiÿcation approaches). Some other noteworthy e orts on system identiÿcation in the civil engineering literature are the works by Ghanem and Shinozuka [6], Hoshiya and Sutoh [7], Masri et al [8], S afak [9], Udwadia and Kuo [10], Lin et al [11], Koh and See [12], and Beck and Katafygiotis [13].…”