| The input ground motion has a significant effect on the damage potential and the seismic design philosophy of buildings and bridges. It is well known that for a given magnitude earthquake, the nature of ground motion for a Western United States (WUS) type earthquake is significantly different from that of a Central and Eastern United States (C&EUS) event. It is well accepted that the earthquakes in WUS are interplate and/or intraplate close to plate boundary while the earthquakes in C&EUS are intraplate events in stable continental interiors.; In this study, the damage potential of intraplate earthquakes (Gazli, 1984, Nahanni, 1985, and Saguenay, 1988) is compared to that of a major California (interplate) earthquake (Loma Prieta, 1989) by analyzing the response of single-degree-of-freedom (SDOF) nonlinear oscillators and real bridges to each record. The comparisons are based on synthetic ground motion records generated by the stochastic method, using source parameters and observed phases from actual records for each earthquake.; SDOF oscillators with natural frequencies between 0.1 and 25 Hz were designed and analyzed. The elastic and inelastic response with different target ductility levels of each oscillator was then calculated at various epicentral distances for each earthquake. The damage potential is characterized by strength demand spectra, strength reduction factor, hysteretic energy, and the number of yield excursions. The results indicated that intraplate earthquakes have larger damage potential to high-frequency {dollar}(f>5{dollar} Hz) structures than interplate earthquakes, especially at larger epicentral distances.; The nonlinear time history responses of bridges designed by current specifications of American Association of State Highway and Transportation Officials (AASHTO) were calculated using a modified NEABS (Nonlinear Earthquake Analysis of Bridge Systems) finite element program. The performance of the bridge piers was evaluated based on displacement ductility demands and on the comprehensive damage index. The results indicate that under the same peak ground acceleration, the responses of intraplate earthquakes are less than those of interplate earthquakes because the first mode frequency of bridge is usually less than 5 Hz. Compared with the AASHTO response spectrum, bridges designed using the AASHTO response spectrum are more conservative and safer. |
