• Wind and Structures
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• v.20 no.6
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• pp.763-791
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• 2015

"Wind and Ports" is a European project that has been carried out since 2009 to handle wind forecast in port areas through an integrated system made up of an extensive in-situ wind monitoring network, the numerical simulation of wind fields, the statistical analysis of wind climate, and algorithms for medium-term (1-3 days) and short term (0.5-2 hours) wind forecasting. The in-situ wind monitoring network, currently made up of 22 ultrasonic anemometers, provides a unique opportunity for detecting high resolution thunderstorm records and studying their dominant characteristics relevant to wind engineering with special concern for wind actions on structures. In such a framework, the wind velocity of thunderstorms is firstly decomposed into the sum of a slowly-varying mean part plus a residual fluctuation dealt with as a non-stationary random process. The fluctuation, in turn, is expressed as the product of its slowly-varying standard deviation by a reduced turbulence component dealt with as a rapidly-varying stationary Gaussian random process with zero mean and unit standard deviation. The extraction of the mean part of the wind velocity is carried out through a moving average filter, and the effect of the moving average period on the statistical properties of the decomposed signals is evaluated. Among other aspects, special attention is given to the thunderstorm duration, the turbulence intensity, the power spectral density and the integral length scale. Some noteworthy wind velocity ratios that play a crucial role in the thunderstorm loading and response of structures are also analyzed.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.5
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• pp.617-628
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• 2018

Several techniques have been developed in the last years for energy conversion and aeronautic propulsion plants monitoring and diagnostics, to ensure non-stop availability and safety, mainly based on machine learning and pattern recognition methods, which need large databases of measures. This paper aims to describe a simulation based monitoring and diagnostic method to overcome the lack of data. An application on a gas turbine powered frigate is shown. A MATLAB-SIMULINK(R) model of the frigate propulsion system has been used to generate a database of different faulty conditions of the plant. A monitoring and diagnostic system, based on Mahalanobis distance and artificial neural networks have been developed. Experimental data measured during the sea trials have been used for model calibration and validation. Test runs of the procedure have been carried out in a number of simulated degradation cases: in all the considered cases, malfunctions have been successfully detected by the developed model.

• Earthquakes and Structures
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• v.18 no.1
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• pp.57-72
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• 2020

This paper presents the results of a monodirectional shaking table test on a full-scale unreinforced masonry cross vault characterized by asymmetric boundary conditions. The specimen represents a vault of the mosque of Dey in Algiers (Algeria), reproducing in detail the mechanical characteristics of masonry, and the constructive details including the presence of some peculiar wooden logs placed within the vault's abutments. The vault was tested with and without the presence of two steel bars which connect two opposite sides of the vault. The dynamic behaviour of both the vault's configurations were studied by using an incremental dynamic analysis up to the collapse of the vault without the steel bars. The use of an innovative high-resolution 3D optical system allowed measure displacement data of the cross vault during the shake table tests. The experimental results were analysed in terms of evolution of damage mechanisms, and in-plane and out-of-plane deformations. Moreover, the dynamic properties of the structure were investigated by means of an experimental modal analysis.

• Advances in robotics research
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• v.2 no.1
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• pp.69-97
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• 2018

Innovation is considered as key to ensure continuous advancement and firm progress in any field. Robotics, with no exception, has gained triumph and approval based on its strength to address divers range of applications as well as its capacity to adapt new ways and means to enhance its applicability. The core of novelty in robotics technology is the perpetual curiosity of human beings to imitate natural systems. This desire urges to continuously explore and find new feet. In the past, contemporary machines, in different shapes, sizes and capabilities, were developed that can perform variety of tasks. The major advantage of these developments was the ability to exhibit superior control, strength and repeatability than the corresponding systems they were replicating. However, these systems were rigid and composed of hard an underlying structure, which is a constraint in bringing into being the compliance that exists in natural organisms. Inspiration of achieving such compliance and to take the full advantage of the design scheme of biological systems compelled researchers and scientists to develop systems avoiding conventional rigid structures. This ambition, to produce biological duos, needs soft and more flexible materials and structures to realize innovative robotic systems. This new footpath to craft biological mockups facilitates further to exploit new materials, novel design methodologies and new control techniques. This paper presents an appraisal on such innovative comprehensions, conferring to their design specific importance. This demonstration is potentially useful to prompt the novelty of soft robotics.

• Wind and Structures
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• v.24 no.6
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• pp.613-635
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• 2017

Strong downslope windstorms often occur in the Liguria Region. This part of North-Western Italy is characterised by an almost continuous mountain range along its West-East axis consisting of Maritime Alps and Apennines, which separate the Padan Plain to the North from the Mediterranean Sea to the South. Along this mountain range many valleys occur, frequently perpendicular to the mountain range axis, where strong gap flows sometimes develop from the top of the mountains ridge to the sea. In the framework of the European projects "Wind and Ports" and "Wind, Ports, and Sea", an anemometric monitoring network made up of 15 (ultra)sonic anemometric stations and 2 LiDARs has been realised in the three main commercial ports of Liguria. Thanks to this network two investigations are herein carried out. First, the wind climatology and the main statistical parameters of one Liguria valley have been studied through the analysis of the measurements taken along a period of 4 years by the anemometer placed at its southern exit. Then, the main characteristics of two strong gap flows that occurred in two distinct valley of Liguria are examined. Both these studies focus, on the one hand, on the climatological and meteorological characterisation of the downslope wind events and, on the other hand, on their most relevant quantities that can affect wind engineering problems.

• Korean Architects
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• no.2 s.52
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• pp.54-65
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• 1973

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.1001-1002
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• 2012

• Structural Engineering and Mechanics
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• v.44 no.5
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• pp.681-704
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• 2012

The dynamic response of Euler-Bernoulli beams to resonant harmonic moving loads is analysed. The non-dimensional form of the motion equation of a beam crossed by a moving harmonic load is solved through a perturbation technique based on a two-scale temporal expansion, which permits a straightforward interpretation of the analytical solution. The dynamic response is expressed through a harmonic function slowly modulated in time, and the maximum dynamic response is identified with the maximum of the slow-varying amplitude. In case of ideal Euler-Bernoulli beams with elastic rotational springs at the support points, starting from analytical expressions for eigenfunctions, closed form solutions for the time-history of the dynamic response and for its maximum value are provided. Two dynamic factors are discussed: the Dynamic Amplification Factor, function of the non-dimensional speed parameter and of the structural damping ratio, and the Transition Deamplification Factor, function of the sole ratio between the two non-dimensional parameters. The influence of the involved parameters on the dynamic amplification is discussed within a general framework. The proposed procedure appears effective also in assessing the maximum response of real bridges characterized by numerically-estimated mode shapes, without requiring burdensome step-by-step dynamic analyses.

• Wind and Structures
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• v.5 no.6
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• pp.527-542
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• 2002

Wind-excited vibrations of slender structures can induce fatigue damage and cause structural failure without exceeding ultimate limit state. Unfortunately, the growing importance of this problem is coupled with an evident lack of simple calculation criteria. This paper proposes a mathematical method for evaluating the crosswind fatigue of slender vertical structures, which represents the dual formulation of a parallel method that the authors recently developed with regard to alongwind vibrations. It takes into account the probability distribution of the mean wind velocity at the structural site. The aerodynamic crosswind actions on the stationary structure are caused by the vortex shedding and by the lateral turbulence, both schematised by spectral models. The structural response in the small displacement regime is expressed in closed form by considering only the contribution of the first vibration mode. The stress cycle counting is based on a probabilistic method for narrow-band processes and leads to analytical formulae of the stress cycles histogram, of the accumulated damage and of the fatigue life. The extension of this procedure to take into account aeroelastic vibrations due to lock-in is carried out by means of ESDU method. The examples point out the great importance of vortex shedding and especially of lock-in concerning fatigue.

• Earthquakes and Structures
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• v.7 no.1
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• pp.57-82
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• 2014

The heritage value of the mixed wood-masonry 18th century Pombalino buildings of downtown Lisbon is recognized both nationally and internationally. The present paper focuses on the seismic assessment of global response and retrofitting of a typical Pombalino building by nonlinear static analyses, performed by the research software Tremuri, which is able to model 3D configurations. The structure is modelled using nonlinear beams for masonry panels, while in case of the internal walls (frontal walls) an original formulation has been developed in order to take into account their specific seismic behaviour. Floors are modelled as orthotropic membrane finite elements: this feature allows to simulate the presence of both flexible and rigid diaphragms, being the first ones more representative of the original state while the second ones of retrofitted configurations. Seismic assessment has been evaluated by applying nonlinear static procedure and comparing the performance of different configurations (by considering various retrofitting strategies). Finally, assuming a lognormal cumulative distribution, fragility curves are obtained to be representative of Pombalino buildings: the most important application of such curves is for seismic risk and loss estimation analyses.