Experimental investigation of inelastic SDOF steel structures using energy-based principals

Abstract

In this research, twenty-eight experimental tests were performed with 0.75-meterhigh single degree of freedom system (SDOF) steel models on a shaking table. Actual scaled 1986 San Salvador earthquake ground motion data was used to excite the SDOF models beyond their elastic displacement limits. The main goal was to verify the existing energy demand spectra, especially within the inelastic range. Elasto-plastic material behavior was considered and responses that were obtained from the experiments were used to calculate the energy quantities for varying natural period of the SDOF system. The damping ratios of the specimens were determined experimentally by means of free vibration after the excitation was completed, and analytically determined through Logarithmic Decrement method. Also, the damping ratios of the specimens were calculated during the earthquake excitation through Chopra's (Chopra, 1995) method. Lastly, an energy spectrum with mass-normalized energy versus natural period of the SDOF system was determined experimentally with respect to varying damping ratios. As a result, experimental data had good agreement with the existing (Gullu, 2019) Energy Spectrum, when data were compared.