Investigation of Damping Ratio and Equivalent Linear System Approach for Buildings Using Strong Earthquake Records

Investigation of Damping Ratio and Equivalent Linear System Approach for Buildings Using Strong Earthquake Records

Part I of this study investigates the equivalent linear system approach for calculating the maximum inelastic displacements of an elastic perfectly plastic SDOF system. Using optimization techniques, new formulas for equivalent period and damping ratio are proposed. The proposed formulas are calibrated using 225 strong earthquake records and are verified using another 225 strong earthquake records. Part II of this study investigates damping ratios of buildings that are identified from strong earthquake motions using the ARMA method. For comparison, damping ratio of buildings identified from ambient vibration measurements are also discussed. It is found that the damping ratios identified from strong motions and identified from ambient vibration measurements have different trends when plotted with the roof responses.