estimating the peak longitudinal near-field seismic response of an isolated bridge using basic pulse motions

The peak dynamic responses of a typical isolated bridge under basic pulse motions and a set of near-field (nf) earthquake records were investigated in this study. a numerical model of the isolated bridge was constructed and validated using seismic response measurements. nonlinear time-history analyses were conducted for the isolated bridge by considering various post-yield stiffness ratios of the isolators and dominant pulse periods of the ground motions. the analysis results revealed that the peak pulse response and mean-plus-one standard deviation of the peak nf seismic response had similar trends of variation with the stiffness ratio. the ratio of the mean-plus-one standard deviation of the peak nf seismic response to the peak pulse response was described using a simple empirical formula. using this formula, the nf seismic response of the isolated bridge could be estimated from the one-cycle type-a pulse motion. the aforementioned ratio was approximated to 0.75 if the pulse period was larger than 6 s. however, the aforementioned ratio varied from 0.1 to 0.5 when the post-yield stiffness ratio varied from 0.1 to 0.45 if the pulse period was 1 s.