Browsing by Author "Garces, E"

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    Ageing effects in the shear modulus of soils
    (ELSEVIER SCI LTD, 2000) Troncoso, JH; Garces, E
    Results of in situ tests of shear wave propagation are presented and analysed to evaluate the effects of geologic processes, stress history and ageing on the shear modulus of soils. These results show clear tendencies of soil structures to get stiffer as consequence of ageing or surcharging to high stress levels. The evolution of shear modulus, as verified by these results, is significant as it changes the response of soil deposits to seismic loadings. (C) 2000 Published by Elsevier Science Ltd.
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    Inelastic deformation response of SDOF systems subjected to earthquakes
    (2002) Riddell, R; Garcia, JE; Garces, E
    Performance-based seismic design requires reliable methods to predict earthquake demands on structures, and particularly inelastic deformations, to ensure that specific damage-based criteria are met. Several methods based on the response of equivalent linear single-degree-of-freedom (SDOF) systems have been proposed to estimate the response of multi-degree-of-freedom structures. These methods do not offer advantages over the traditional Veletsos-Newmark-Hall (VNH) procedure, indeed, they have been shown to be inaccurate. In this study, the VNH method is revised, considering the inelastic response of elastoplastic, bilinear, and stiffness-degrading systems with 5% damping subjected to two sets of earthquake ground motions. One is an ensemble of 51 earthquake records in the Circumpacific Belt, and the other is a group of 44 records in California. A statistical analysis of the response data provides factors for constructing VNH inelastic spectra. Such factors show that the 'equal-displacement' and 'equal-energy' rules to relate elastic and inelastic responses are unconservative for high ductilities in the acceleration- and velocity-sensitive regions of the spectrum. It is also shown that, on average, the effect of the type of force-deformation relationship of non-linear systems is not significant, and responses can be conservatively predicted using the simple elastoplastic model. Copyright (C) 2001 John Wiley Sons, Ltd.