An earthquake response spectrum method for linear light secondary substructures

YesEarthquake response spectrum is the most popular tool in the seismic analysis and design of structures. In the case of combined primary-secondary (P-S) systems, the response of the supporting P substructure is generally evaluated without considering the S substructure, which in turn is only required to bear displacements and/or forces imposed by the P substructure (¿cascade¿ approach). In doing so, however, dynamic interaction between the P and S components is neglected, and the seismic-induced response of the S substructure may be heavily underestimated or overestimated. In this paper, a novel CQC (Complete Quadratic Combination) rule is proposed for the seismic response of linear light S substructures attached to linear P substructures. The proposed technique overcomes the drawbacks of the cascade approach by including the effects of dynamic interaction and different damping in the substructures directly in the cross-correlation coefficients. The computational effort is reduced by using the eigenproperties of the decoupled substructures and only one earthquake response spectrum for a reference value of the damping ratio

Peak response of non-linear oscillators under stationary white noise

The use of the Advanced Censored Closure (ACC) technique, recently proposed by the authors for predicting the peak response of linear structures vibrating under random processes, is extended to the case of non-linear oscillators driven by stationary white noise. The proposed approach requires the knowledge of mean upcrossing rate and spectral bandwidth of the response process, which in this paper are estimated through the Stochastic Averaging method. Numerical applications to oscillators with non-linear stiffness and damping are included, and the results are compared with those given by Monte Carlo Simulation and by other approximate formulations available in the literature

Response of beams resting on viscoelastically damped foundation to moving oscillators

The response of beams resting on viscoelastically damped foundation under moving SDoF oscillators is scrutinized through a novel state-space formulation, in which a number of internal variables is introduced with the aim of representing the frequency-dependent behaviour of the viscoelastic foundation. A suitable single-step scheme is provided for the numerical integration of the equations of motion, and the Dimensional Analysis is applied in order to define the dimensionless combinations of the design parameters that rule the responses of beam and moving oscillator. The effects of boundary conditions, span length and number of modes of the beam, along with those of the mechanical properties of oscillator and foundation, are investigated in a new dimensionless form, and some interesting trends are highlighted. The inaccuracy associated with the use of effective values of stiffness and damping for the viscoelastic foundation, as usual in the present state-of-practice, is also quantified

Religione e razionalità comunicativa. Juergen Habermas e la " Nuova Teologia Politica"

Jürgen Habermas’ recent work is focused on the relationship between reason and faith in what he suggest that we should name post-secular society. Habermas argues that traditional religions such as Christianity can have semantic contents very useful to uphold a moral motivation in order to contrast the instrumental reason of the globalized markets. I will try to show that these recent developments of Habermas’ theories risk to conflict with some elements of his previous approach. As a consequence, I suggest that we carefully look to the critiques that the catholic theologian J. B. Metz made to Habermas’ previous approach. In fact, I argue that Metz’s proposal of a “New Political Theology”, which is characterized by the concept of anamnestic reason, shows how to overcome, or complete, some limits of the first formulation of the theory of communicative rationality. Nevertheless, Habermas’ recent openness on these topics, even if problematic with his previous approach, stimulates to rethink on the relationship between reason and faith, religion and democracy

Some Philosophical Remarks on the Encyclical Letter Laudato Si’

In this paper, I aim at interpreting the project of the encyclical as a sort of paradigmatic turn in the way of conceiving Christian faith. At paragraph 49, it is underlined that a “true ecological approach always becomes a social approach” and this implies the need of hearing “both the cry of the earth and the cry of the poor”. In my view, by uniting the two categories of “nature/creation” and “poverty”, the encyclical implicitly builds an ideal bridge between Pope Francis’ paradigmatic turn and that “political turn” invoked by the Catholic theologian J. B. Metz from the end of the sixties through the proposal of a “New Political Theology”. Indeed, the excesses of the neo-liberal paradigm and the perverse effects of a certain organization of global market pushes Christianity to act by involving all social, cultural and religious actors, in order to fight against all the forms of suffering and dehumanization of contemporary society. I’m also interested in underlining some weak aspects of Pope’s ecological approach

Wittgenstein al fronte

Il saggio descrive l'esperienza del giovane Wittgenstein al fronte durante la prima guerra mondiale dove maturano le idee che confluiscono nel Tractatus

L'orizzonte mobile. Su Koselleck

Discussione del libro di D. Fusaro sull'approccio storiografico di R. Koselleck in dialogo critico con la Cambridge Schoo