Browsing by Author "Riddell, R"

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    An integrated model for earthquake risk assessment of buildings
    (ELSEVIER SCI LTD, 2002) Fischer, T; Alvarez, M; Llera Martin, Juan Carlos de la; Riddell, R
    This study is devoted to the formulation and construction of an integrated model for earthquake risk assessment of buildings in seismic regions. The model developed has five stages: i) characterization of ground motion, ii) construction of the building model, iii) evaluation of the inelastic building response, iv) structural damage assessment, and v) risk evaluation. Stages iii) and iv) are emphasized in the current presentation, because they include some newer aspects such as the use of story-shear and torque surfaces for inelastic building analysis and fuzzy logic for assessing the earthquake performance of a structure. Examples including a large building inventory and two individual structures are developed to show the potential use of the model. Results show that the model is capable of discriminating different foundation soils, earthquake performance of shear-wall and frame buildings, asymmetries in height and plan, and between conventional and seismically isolated structures. Such features may be useful to engineers working in city planning, emergency and risk management, and the insurance industry. (C) 2002 Elsevier Science Ltd. All rights reserved.
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    Hysteretic energy spectrum and damage control
    (JOHN WILEY & SONS LTD, 2001) Riddell, R; Garcia, JE
    The inelastic response of single-degree-of-freedom (SDOF) systems subjected to earthquake motions is studied and a method to derive hysteretic energy dissipation spectra is proposed. The amount of energy dissipated through inelastic deformation combined with other response parameters allow the estimation of the required deformation capacity to avoid collapse for a given design earthquake. In the first part of the study, a detailed analysis of correlation between energy and ground motion intensity indices is carried out to identify the indices to be used as scaling parameters and base line of the energy dissipation spectrum. The response of elastoplastic, bilinear, and stiffness degrading systems with 5 per cent damping, subjected to a world-wide ensemble of 52 earthquake records is considered. The statistical analysis of the response data provides the factors for constructing the energy dissipation spectrum as well as the Newmark-Hall inelastic spectra. The combination of these spectra allows the estimation of the ultimate deformation capacity required to survive the design earthquake, capacity that can also be presented in spectral form as an example shows. Copyright (C) 2001 John Wiley & Sons, 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.
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    Inelastic response of one-storey asymmetric-plan systems subjected to bi-directional earthquake motions
    (1999) Riddell, R; Santa-Maria, H
    The inelastic response of one-storey systems with one axis of asymmetry subjected to bi-directional base motion is studied in this paper. The effect of the system parameters on response is also evaluated: uncoupled torsional-to-lateral frequency ratio, stiffness eccentricity, and yield strength of the lateral resisting elements. The ensemble of earthquake records used consists of 15 two-component strong ground motions. The response to uni-directional excitation is considered first to examine the influence of the system parameters and to serve as a basis to examine the results of the bi-directional case, which are presented in terms of average spectra for bi- over uni-directional lateral-deformation ratios. It is shown that the effect of inelastic behaviour is, on the average, noteworthy for stiff structures, in turn, the same structures are the most affected by the action of bi-directional ground motions. The effect of the relative intensity of the two orthogonal ground motion components is also studied. Copyright (C) 1999 John Wiley & Sons, Ltd.