A comparative study of linear and nonlinear mass damping systems under seismic excitation

A comparative study of the seismic response of structures equipped with linear and nonlinear mass damping systems is presented herein. Three optimized mass damping systems mounted at the top of a linearly elastic two - degree -of -freedom building are tested under an artificial seismic motion to assess their response. The artificial seismic motion is generated using the SIMQKE software and matching a specific response spectrum. The mass damping systems consist of (i) a Linear Mass Damper (LMD), (ii) a type -I Nonlinear Energy Sink (NES) with a nonlinear elastic spring of the cubic oscillator, and (iii) a Friction Nonlinear Energy Sink (FNES) which extends the NES with a friction element and a linear elastic spring of potentially negative stiffness. The results for each configuration are validated with a set of real scaled ground motion time histories matching the same specific spectrum, and a quantification of the response variability in relation to the input variability is attempted. An interesting observation is that the artificially generated excitation consistently underestimates critical design/ response quantities, as compared to the average response of the set of real ground motions.