Kinematic soil-structure interaction effects on maximum inelastic displacement demands of SDOF systems

Abstract

This paper presents a statistical study of the kinematic soil-foundationstructure interaction effects on the maximum inelastic deformation demands of structures. Discussed here is the inelastic displacement ratio defined as the maximum inelastic displacement demands of structures subjected to foundation input motions divide by those of structures subjected to free-field ground motions. The displacement ratio is computed for a wide period range of elasto-plastic single-degree-of-freedom (SDOF) systems with various levels of lateral strength ratios and with different sizes of foundations. Seventy-two earthquake ground motions recorded on firm soil with average shear wave velocities between 180 m/s and 360 m/s are adopted. The effects of period of vibration, level of lateral yielding strength and dimension of foundations are investigated. The results show that kinematic interaction will reduce the maximum inelastic displacement demands of structures, especially for systems with short periods of vibration, and the larger the foundation size the smaller the maximum inelastic displacement becomes. In addition, the inelastic displacement ratio is nearly not affected by the strength ratio of structures for systems with periods of vibration greater than about 0.3 s and with strength ratios smaller than about 3.0. Expressions obtained from nonlinear regression analyses are also proposed for estimating the effects of kinematic soil-foundation-structure interaction from the maximum deformation demand of the inelastic system subjected to free-field ground motions.

Filtering action of embedded massive foundations: New analytical expressions and evidence from 2 instrumented buildings

“…With reference to the filtering action of the foundation, the important role of kinematic interaction has been established in the case of embedded foundations, where the foundation input motion can differ substantially from the free‐field motion at ground surface. The resulting effect is usually beneficial for squat structures while it may be detrimental for slender buildings with deeply embedded foundations or basements by increasing the ductility demand . The above has also been observed from recordings of instrumented buildings during real earthquakes, where, however, the recorded base slab motion stems from both inertial and kinematic interaction between the structure and the soil‐foundation system.…”

Soil structure interaction (SSI) analysis of shear wall buildings with a below-ground parkade

“…However, soil-structure interaction causes a difference between the two because of the base slab averaging effect. The presence of stiff foundation As stated in the literature (Lin et al 2008& Hossein et al 2013, the main effect of kinematic interaction is to filter the high-frequency components of the free field motion, and the same is observed as detailed in the following figures, From the above plots, it is observed that the spectra of accelerations recorded at the base of the structure are de-amplified for all the cases when compared with the free field spectra for the same site condition. Hence, there is a reduction in seismic demand on the structures owing to the base slab averaging effect.…”

Development of duration‐dependent damage‐based inelastic response spectra

“…The ground motion accelerograms were collected from the PEER Strong Motion Database , the PEER Next Generation Attenuation database , and the COSMOS Virtual Data Center . Selected ground motions were recorded on free field stations or in the first floor or basement of low‐rise buildings with negligible soil‐structure interaction effects . It should be noted that the selected records were compiled from the datasets previously employed by Lu and Wei and Raghunandan and Liel .…”