4,894 research outputs found
Seismic vulnerability assessment based on typological characteristics. The first level procedure “SAVE”
No full textIn this paper a procedure is described for quick seismic vulnerability assessment according to the EMS 98 classification. The criteria adopted by Ems 98 to assign the typological classes are mainly based on the vertical structure type. The proposed methodology aims to reduce the uncertainty in the class assessment using a set of parameters, related to typological features, that are identified as modifiers of the vulnerability level. The paper shows how the weight of each of these parameters is evaluated through the analysis of the seismic damages recorded during past earthquakes. A synthetic damage parameter is then defined in order to compare the seismic response of different sets of buildings under the same seismic intensity. Finally, the vulnerability assessment obtained on a set of buildings by the application of the methodology is compared with expert evaluations derived from the direct inspections on buildings
Seismic vulnerability assessment of the masonry buildings based on the probability of occurrence of the main collapse mechanisms. Damage Vulnerability Curves vs. PGA.
No full text
Filtering Continuous-Time Linear Systems With Time-Varying Measurement Delay
No full textWe consider the filtering problem of LTI continuous-
time systems with known and bounded measurement delays. The
aim of the technical note is the design of a finite-dimensional
sub-optimal filter whose performance in terms of the estimation
error is comparable to optimal infinite-dimensional approaches.
We show that the proposed approach allows for a precise char-
acterization of the relationship between measurement delay and
the covariance of the estimation error. In the time-varying case no
restrictive hypotheses on the delay function are needed. The pro-
posed filter can therefore be applied to delay functions for which
traditional infinite-dimensional approaches cannot be straightfor-
wardly applied
Seismic casualty evaluation: the Italian model, an application to the L'Aquila 2009 event.
No full textIn this chapter a possible model for evaluating seismic casualties in Italy is presented. The factors influencing the evaluation are discussed and the results of the first investigations concerning their quantification are presented. The model is directly derived from the original idea of Coburn and Spence (1992); the adaptation of the model to the Italian context has been possible thanks to the data collected in the field regarding either the percentage of the victims per structural type or the lifestyle of the population obtained from the National Institute of Statistics (ISTAT). This has enabled the estimation of some of the most important parameters: the time and duration of the indoor occupancy of the population in the day, in the week, in the year. Other factors, such as the increment of population due to seasonal tourist flows or the increase of low energy seismic activity before the damaging event are discussed. Finally an application of the model to the earthquake of L’Aquila which occurred on 6 April 2009 is presented. The comparison of the official data of the human and structural damage with the simulation results show very good agreement. Considering the considerable uncertainty of the separate factors influencing the final evaluation of the casualty model, this result has to be taken with great caution and considered a favourable case rather than proof of the reliability of the model; however it represents an encouraging step toward the definition of a reliable casualty model while acknowledging that further investigation and calibration are required
A probabilistic model for the evaluation of the impact of explosive eruption scenarios at Vesuvius
No full textState Feedback Stabilization of Linear Systems with Unknown Input Time Delay
No full textThis paper investigates the control problem of linear systems affected by an unknown constant input delay by means of a finite-dimensional state feedback. The proposed solution extends an approach used in the case of known delays by means of a suitably developed delay identifier. A more general result about the convergence to zero of the controlled system when the delay estimation error only converges to some neighborhood of zero is provided. Numerical examples show the effectiveness of the proposed approach
Memoryless Approach to the LQ and LQG Problems with Variable Input Delay
No full textThis note studies the LQ and LQG problems for linear time invariant systems with a single time-varying input delay and instantaneous (memoryless) state feedback. We extend the memoryless state feedback solution proposed in [1] in two directions. We prove that in the deterministic case a memoryless state feedback can be in general optimal only up to a certain delay, for which we provide a sufficient, and sometimes strict, bound. Moreover, we show that this memoryless control is optimal also in the case of time-varying delays and that the quadratic cost functional has the same value as in the case without delay. For time varying delays the control law requires that the relationship between time points in which the input is generated and applied is known and invertible even if the delay function needs not to be differentiable or even continuous. Finally, we prove that the cost functional is bounded also in the stochastic case for the same delay interval as in the deterministic case, but with a larger cost than the delay-less LQG solution
A New Filtering Approach for Continuous-Time Linear Systems with Delayed Measurements
No full textThis paper introduces a new filter for linear continuous-time stochastic systems with delayed measurements. The approach is inspired by an observer designed for deterministic systems. The obtained solution is suboptimal and does not use distributed integration terms with advantages in terms of computational load. The relationship between the delay bound and the variance of the estimation error is formally characterized and confirmed by a numerical example
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