Vibration studies and tests of a suspension bridge

The natural frequencies of the San Pedro‐Terminal Island Suspension Bridge were fairly accurately determined by measuring traffic‐excited vertical vibrations with sensitive seismometers mounted at various locations on the bridge. The Fourier amplitude spectrum of the recorded vertical movements was computed and plotted. The measurements revealed a wide band of natural frequencies. The results for the vertical and torsional natural frequencies were correlated with the computed frequencies. The results of the field measurements showed reasonable agreement with the computed values. Finally, further recommendations toward obtaining better results were also indicated.