1. The center span of a bicycle overcrossing can be closely approximated as a linear-elastic, single degree of freedom system with 5% damping and a natural frequency of 1.5 Hz. If this structure is shaken horizontally by a ground motion whose 5% damped pseudo acceleration response spectra is shown below, estimate the peak relative displacement between the superstructure (overcrossing deck) and the ground surface.

0.5 Damping ratio 5% 0.4 0.3 Spectral acceleration (9) 0.2 0.1 0 0.01 0.1 10 Period (sec) 0.5 Damping ratio 5% 0.4 0.3 Spectral acceleration (9) 0.2 0.1 0 0.01 0.1 10 Period (sec)