Seismic Control of Adjacent Structures using a Nonlinear Friction Amplifier Damper under Bidirectional Horizontal Excitation

Abstract

Closely spaced adjacent structures are vulnerable to dynamic interaction during earthquakes, which may amplify structural responses and increase seismic damage. Although various passive control devices have been proposed for adjacent structures, nonlinear friction-based control under simultaneous bidirectional horizontal ground motions remains comparatively less explored, and efficient analytical tuning methodologies for such devices are limited. This study proposes a Nonlinear Dynamic Amplifier Friction Vibration Absorber (NDAFVA) for mitigating the earthquake-induced response of adjacent structures subjected to bidirectional horizontal ground motions. Nonlinear dynamic models are developed for Single-Degree-of-Freedom (SDOF) and Multi-Degree-of-Freedom (MDOF) systems by combining dynamic amplification with nonlinear frictional energy dissipation. The NDAFVA is evaluated under cyclic pulse excitations and twenty recorded near-field and far-field earthquake ground motions. Optimal absorber parameters are determined using hybrid H 2 /H∞ optimization, and closed-form tuning relationships are derived using Taylor-series-based analytical formulations. The NDAFVA provides substantial response mitigation across the considered seismic excitations. For Across the 20 ground motions, the maximum reductions in peak acceleration and displacement are 69% and 72.5%, respectively, while the mean and standard-deviation values are also reported in Tables 3 and 4. The closed-form tuning relationships closely reproduce the optimized parameters and provide greater response reduction than conventional H 2 and H∞ tuning for the benchmark systems considered. These results demonstrate that combining dynamic amplification with nonlinear frictional energy dissipation provides an effective passive control strategy, while the proposed closed-form relationships offer a computationally efficient approach for preliminary seismiccontrol design of adjacent structures.