Assessment of UBC Seismic Design Provisions using Recorded Building Motions

Abstract

Recorded motions in two 10-story reinforced concrete buildings from three different earthquakes are analyzed in order to assess UBC seismic design provisions. In this, a proven system identification method (MODE-ID) has been applied to each set of recorded motions and the corresponding normal modes of vibration have been identified. These modal parameters were used to compute earthquake-induced forces, shears, moments, and drifts. Example results presented in this paper from the 1989 Lorna Prieta earthquake motions show that the computed forces and moments exceed the corresponding UBC design values, but the computed interstory drift is substantially less than the code allowable. This comparison in conjunction with the lack of damage to the buildings during the earthquake has indicated the importance of the interstory drift as a measure of the severity of the seismic demand on buildings.