Simplified Earthquake Analysis of Suspension Bridge Towers

Free vibration and earthquake response analyses of a simplified continuous analytical model representing suspension bridge towers (fixed at the base) are presented. In addition, various models for seismic analysis of the towers are proposed. These models take into account, among other things, the flexibility of the surrounding soils and the multiple-seismic inputs. The earthquake response of some existing suspension bridges' towers, including the Golden Gate Bridge and the Vincent-Thomas Bridge is analyzed, and stresses (both vibrational and quasi-static) induced by different earthquake ground motions in these two bridges are examined. Both time history response and the classical response spectra are considered.