Isolation of soil‐structure interaction effects by full‐scale forced vibration tests

Abstract

SUMMARYForced vibration tests designed to isolate the effects of soil-structure interaction are described and the results obtained for the nine-storey reinforced concrete Millikan Library Building are analysed. It is shown that it is possible to determine experimentally the fixed-base natural frequencies and modal damping ratios of the superstructure. These values may be significantly different from the resonant frequencies and damping ratios of the complete structure-foundation-soil system. It is also shown that forced vibration tests can be used to obtain estimates of the foundation impedance functions.In the case of the Millikan Library it is found that during forced vibration tests the rigid-body motion associated with translation and rocking of the base accounts for more than 30 per cent of the total response on the roof and that the deformation of the superstructure at the fundamental frequencies of the system is almost entirely due to the inertial forces generated by translation and rocking of the base.

Identification of structural and soil properties from vibration tests of the Hualien containment model

“…which reduces to (11) has been presented by Luco et al [8,9]. Applying Equation (11) to the data for the vibration tests prior to backÿll (FVT-1) leads to the results for f 1 = !…”

“…A second identiÿcation approach [8,9] assumes that the modal properties M 1 , ÿ 1 and 1 are known. In this approach Equation (6) is written in the form…”

Field Testing Capabilities of the NEES@UCLA Equipment Site for Soil-Structure Interaction Applications

“…Testing by Luco et al (1988) was performed on a full-scale structure (i.e., the 9-story Millikan Library on the Caltech campus). The results were used to evaluate whether simple impedance function models could reproduce the observed foundation impedance functions.…”

Detection thresholds in structural health monitoring

“…We will also consider some results based on the forced-vibration tests [65], but most of our examples will be drawn from studies of the recorded responses of several buildings during strong earthquake shaking. We will use wave-propagation methods to interpret structural response [38,53,67,80,81,93,95,96,[104][105][106][107]131,94,28,29], and to monitor changes in response time and amplitude we will use moving-window Fourier analyses [141,142], impulseresponse analysis [90], and interpretation of novelties in terms of wavelet decomposition of time series [97,103].…”