A robust nonlinear semi-active control for base seismically-isolated structures

This paper proposes a robust nonlinear semi-active control for base seismically-isolated structures. The control is based upon an extension of works of Leitmann et al. on the stabilization of nonlinear systems with uncertain models. For usual models of structure dynamics it is shown that applying a specific control law drives the state variables into a ball of specified radius in finite time. The radius of the ball may be arbitrarily chosen as long as it is not lower than a limiting value. In addition, estimates of this limiting ball radius is provided. The time to reach the ball is also provided. The semi-active control thus provides the control designer with interesting design parameters. The efficacy of proposed semiactive control is illustrated by its application to simple models of structures focusing in particular to the attenuation of excitation transmitted from floor to equipment mounted on them

A semi-active controller tuning and application to base seismically-isolated structures

International audienceThis paper proposes a modified version of Leitmann and co-authors' classical result on the stabilization of uncertain nonlinear systems. In particular, for usual models of structure dynamics in earthquake engineering it is shown that applying a specific control law drives the state variables into a ball around the origin (arbitrarily chosen) in finite time as long as the radius of the ball is not lower than a limiting value. In addition estimates of this limiting ball radius and the time limit for arbitrary ball radius are provided. The semi-active control thus provides the control designer with interesting design parameters. It is also an attempt to explicitly use pseudoacceleration floor response spectrum as a performance criterion. Though not limited to twodegree- of-freedom structures, this semi-active control is applied to these plant models for simplicity and illustrated through simulations

A Serious Game Approach in Anti-Doping Education: the Game Project

Anti-doping education has largely relied on traditional educational approaches such as face-to-face interaction and e-learning material. Current challenges in anti-doping education involve a) the development of modern educational tools suitable for the new generation of athletes, b) the use of state-of- art learning pedagogies that will enable effective engagement, learning and retention of the learned material, c) a systematic evaluation of the outcomes of anti-doping educational interventions on behavior and related cognition, and d) a positive approach to doping prevention. Project GAME aims to address these needs through the development of a serious game that will incorporate current empirical evidence on the psychological mechanisms underpinning the decision making process towards doping use in competitive and recreational sports. The aim of the present study is to highlight the importance of anti-doping education, conduct a state of the art literature review on serious games' design, present the prototype of a scenario that will be included in a serious game for anti-doping education, and discuss the project's activities related to the use of technologies in anti-doping education. +++++++++++++ Anti-doping education has largely relied on traditional educational aproaches such as face-to-face interaction and e-learning material. Current chalenges in anti-doping education involve a) the development of modern educational tools suitable for the new generation of athletes, b) the use of state-of- art learning pedagogies that will enable effective engagement, learning and retention of the learned material, c) a systematic evaluation of the outcomes of anti-doping educational interventions on behavior and related cognition, and d) a positive approach to doping prevention. Project GAME aims to address these needs through the development of a serious game that will incorporate current empirical evidence on the psychological mechanisms underpinning the decision making process towards doping use in competitive and recreational sports. The aim of the present study is to highlight the importance of anti-doping education, conduct a state of the art literature review on serious games' design, present the prototype of a scenario that will be included in a serious game for anti-doping education, and discuss the project's activities related to the use of technologies in anti-doping educatio

Experimental and numerical investigation of the earthquake response of crane bridges

© 2014 Elsevier Ltd. The experimental and numerical response of crane bridges is studied in this work. To this end, an experimental campaign on a scale model of an overhead crane bridge was carried out on the shaking table of CEA/Saclay in France. A special similarity law has been used which preserves the ratios of seismic forces to friction forces and of seismic forces to gravity forces, without added masses. A numerical model, composed of beam elements, which takes into account non-linear effects, especially impact and friction, and simulates the earthquake response of the crane bridge, is presented. The comparison of experimental and analytical results gives an overall satisfactory agreement. Finally, a simplified model of the crane bridge, with only a few degrees of freedom is proposed

Effective linear damping and stiffness coefficients of nonlinear systems for design spectrum based analysis

A stochastic approach for obtaining reliable estimates of the peak response of nonlinear systems to excitations specified via a design seismic spectrum is proposed. This is achieved in an efficient manner without resorting to numerical integration of the governing nonlinear equations of motion. First, a numerical scheme is utilized to derive a power spectrum which is compatible in a stochastic sense with a given design spectrum. This power spectrum is then treated as the excitation spectrum to determine effective damping and stiffness coefficients corresponding to an equivalent linear system (ELS) via a statistical linearization scheme. Further, the obtained coefficients are used in conjunction with the (linear) design spectrum to estimate the peak response of the original nonlinear systems. The cases of systems with piecewise linear stiffness nonlinearity, along with bilinear hysteretic systems are considered. The seismic severity is specified by the elastic design spectrum prescribed by the European aseismic code provisions (EC8). Monte Carlo simulations pertaining to an ensemble of nonstationary EC8 design spectrum compatible accelerograms are conducted to confirm that the average peak response of the nonlinear systems compare reasonably well with that of the ELS, within the known level of accuracy furnished by the statistical linearization method. In this manner, the proposed approach yields ELS which can replace the original nonlinear systems in carrying out computationally efficient analyses in the initial stages of the aseismic design of structures under severe seismic excitations specified in terms of a design spectrum

1st year EFAST annual report

The present report provides information about the activities conducted during the 1st year of the EFAST project. The first chapter is dedicated to describe the inquiries conducted at the beginning of the project and to briefly summarise the main results. The second chapter is dedicated to the first EFAST workshop where some of the leading scientists in the field of earthquake engineering have met to discuss about the need and the technologies related to earthquake engineering. The third chapter contains a state of the art and future direction in seismic testing and simulation. The final chapter is dedicated to describe the preliminary design of the web portal of the future testing facility.JRC.DG.G.5-European laboratory for structural assessmen

An overview of seismic testing needs in Europe: towards a new advanced experimental facility

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Stochastic models of the Brownian motion

This paper presents an exposition of the stochastic models for the Brownian motion. The results of Einstein and Wiener are presented, together with the Uhlenbeck-Ornstein process which gives a more realistic model of the Brownian motion of a particle. Finally, applying a one-one transformation on the forward Kolmogorov equation we have shown that the Uhlenbeck-Ornstein process can be transformed into the Wiener process