Abstract
Shock response analysis of the soil-structure systems induced by near-fault pulses is investigated. Vibration transmissibility of the soil-structure systems is evaluated by Shock Response Spectra (SRS). Medium-to- high rise buildings with different aspect ratios located on different soil types as well as different foundations with respect to vertical load bearing safety factors are studied. Two types of mathematical near-fault pulses, i.e., forward directivity and fling step, with different pulse periods as well as pulse amplitudes are selected as incident ground shock. Linear versus nonlinear Soil-Structure Interaction (SSI) condition are considered alternatively and the corresponding results are compared. The results show that nonlinear SSI is likely to amplify the acceleration responses when subjected to long-period incident pulses with normalized period exceeding a threshold. It is also shown that this threshold correlates with soil type, so that increased shear-wave velocity of the underlying soil makes the threshold period decrease.
Highlights
Shock and vibration isolation reduces the excitation transmitted to systems requiring protection
The dampers act by dissipating energy to reduce the amplification of forces that occur at resonance (Piersol and Paez, 2010)
The first concerns about this issue were arisen after 1992 Landers and 1994 Northridge earthquakes, where long-period pulse-type ground motions were observed in near-fault records
Summary
Shock and vibration isolation reduces the excitation transmitted to systems requiring protection. Past studies in the literature reveal that nonlinear Soil-Structure Interaction (SSI) including foundation uplift and soil yield can exhibit base isolating effects due to hysteretic damping of the underlying soil These effects can be significant during strong ground motions when the superstructure is mounted on a shallow foundation with sufficiently low static vertical load bearing safety factor (Anastasopoulos et al, 2010). Geometry of the superstructure should enable the rocking motions of the foundation to emerge as a remarkable mode of vibration in seismic performance of the soil-structure system In such condition, the so-called inverted-pendulum structures (Housner, 1963) can benefit from energy absorbing capacity of the underlying soil namely rocking isolation. Linear versus nonlinear SSI condition are considered alternatively and the corresponding results are compared
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Published Version
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