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In this study, dynamic responses of two buildings connected by viscoelastic dampers under bidirectional excitations are extensively investigated. The two buildings are a 10-story building and a 16-story building, with the shorter building on the left. Viscoelastic dampers are installed at all floors of the shorter building. Equations of motion are formulated using a fractional derivative model to represent the viscoelastic dampers. Three cases are considered with mass eccentricities at 0, 10% and −10% with respect to the dimensions of the buildings. The responses of the buildings are numerically predicted at different damper properties. The simulation results indicated that the maximum horizontal responses of the buildings without eccentricities are significantly mitigated. However, torsional effects are adversely increased. For asymmetric buildings, the effectiveness of the connecting dampers is affected by building eccentricities. As a result, mass eccentricities must be taken into account in damper selection. When compared with vibrations induced by unidirectional excitations, bidirectional excitations can increase the responses of coupled asymmetric buildings. In addition, installing dampers only at the top floor of the shorter building may cause a sudden change in lateral stiffness of the taller building. Consequently, the story shear envelopes of the taller building are changed. [ABSTRACT FROM AUTHOR]

Many closely located adjacent buildings have suffered from pounding during past earthquakes because they vibrated out of phase. Furthermore, buildings are usually constructed on soil; hence, there are interactions between the buildings and the underlying soil that should also be considered. This paper examines both the interaction between adjacent buildings due to pounding and the interaction between the buildings through the soil as they affect the buildings' seismic responses. The developed model consists of adjacent shear buildings resting on a discrete soil model and a linear viscoelastic contact force model that connects the buildings during pounding. The seismic responses of adjacent buildings due to ground accelerations are obtained for two conditions: fixed-based (FB) and structure-soil-structure interaction (SSSI). The results indicate that pounding worsens the buildings' condition because their seismic responses are amplified after pounding. Moreover, the underlying soil negatively impacts the buildings' seismic responses during pounding because the ratio of their seismic response under SSSI conditions with pounding to those without pounding is greater than that of the FB condition. [ABSTRACT FROM AUTHOR]