Stefano LENCI

Pubblicazioni

Stefano LENCI

 

424 pubblicazioni classificate nel seguente modo:

Nr. doc. Classificazioni
215 1 Contributo su Rivista
125 4 Contributo in Atti di Convegno (Proceeding)
68 2 Contributo in Volume
6 5 Altro
6 7 Curatele
3 3 Libro
1 6 Brevetti
Anno
Risorse
Global Nonlinear Dynamics for Engineering Design and System Safety
CISM INTERNATIONAL CENTRE FOR MECHANICAL SCIENCES
Autore/i: Lenci, Stefano; Rega, Giuseppe
Classificazione: 7 Curatele
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/261164 Collegamento a IRIS

Dynamical Integrity: A Novel Paradigm for Evaluating Load Carrying Capacity
Global Nonlinear Dynamics for Engineering Design and System Safety
Autore/i: Rega, G.; Lenci, S.; Ruzziconi, L.
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/261165 Collegamento a IRIS

Nonlinear Dynamics, Safety, and Control of Structures Liable to Interactive Unstable Buckling
Global Nonlinear Dynamics for Engineering Design and System Safety
Autore/i: Goncalves, P. B.; Orlando, D.; Silva, F. M. A.; Lenci, S.; Rega, G.
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/261167 Collegamento a IRIS

Interpreting and Predicting Experimental Responses of Micro- and Nano-Devices via Dynamical Integrity
Global Nonlinear Dynamics for Engineering Design and System Safety
Autore/i: Ruzziconi, L.; Lenci, S.; Younis, M.
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/261166 Collegamento a IRIS

2021
TRM reinforced tuff and fired clay brick masonry: Experimental and analytical investigation on their in-plane and out-of-plane behavior
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Donnini, J.; Maracchini, G.; Lenci, S.; Corinaldesi, V.; Quagliarini, E.
Classificazione: 1 Contributo su Rivista
Abstract: The paper presents the results of an experimental campaign aimed at investigating the in-plane and out-of-plane behavior of tuff and fired clay brick masonry panels reinforced by a commercial, not yet tested, Textile Reinforced Mortar (TRM) system. The TRM, consisting of hydraulic lime mortar coupled with a bidirectional glass fabric (total thickness of 30 mm), was applied on both sides of the panels and connected through stainless-steel helical bars. First, a mechanical characterization of the TRM system was carried out, according to recent guidelines (AC434 and CNR-DT215) by means of tensile tests and single-shear bond tests on the two different substrates. Then, the effectiveness of the reinforcement was investigated through uniaxial compression, diagonal compression and three-point bending tests on masonry panels. After that, experimental results were compared to the predictions of recent guidelines and analytical models available in the literature, by using the mechanical parameters obtained from the TRM mechanical characterization. TRM showed to be very effective in increasing the in-plane shear strength of tuff panels, of about 170%, whereas in the case of fired clay brick ones the increase was limited to 33%. Besides, the diagonal compression strength of reinforced specimens seemed to be strongly influenced by the mortar matrix, instead of by the fabric reinforcement, as it usually happens i.e. for Fabric Reinforced Cementitious Matrix (FRCM) systems. Thus, novel simplified analytical formulations to predict the shear strength of reinforced panels by only considering the contribution of the TRM matrix were provided, discussed and compared to current analytical approaches for FRCM systems. As regards the out-of-plane behavior, the TRM system significantly increased the out-of-plane bending strength and ductility of both tuff and fired clay brick panels. The applicability of current analytical approaches, as well as possible amendments, was also investigated. Finally, the compressive behavior of the walls was not substantially modified by the reinforcement, reasonably due to the low axial stiffness of the connectors and, to a minor extent, because they were dry inserted within the masonry and simply folded over the glass fabric.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287962 Collegamento a IRIS

2021
Size-dependent response of electrically pre-deformed micro-plates under mechanical shock incorporating the effect of packaging, a frequency-domain analysis
JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING
Autore/i: Askari, A. R.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: Complementing the time-history solution by the frequency-domain analysis can provide a better understanding of micro-structures dynamics. Nevertheless, there exist no research studies in the literature dealing with the dynamics of plate-type MEMS undergoing mechanical shock via the frequency-domain analysis. Therefore, the main object of the present work is to introduce a frequency-domain analysis for predicting the size-dependent behavior of packaged plate-type MEMS experiencing shock environments. To this end, employing the Hamilton principle, the coupled governing equations of motion are obtained based on the modified couple stress geometric nonlinear thin plate theory and reduced to a system of initial value problems utilizing the Galerkin weighted residual method. The accuracy of the present model is validated by available results in the literature as well as those obtained through three-dimensional finite element simulations performed in COMSOL Multiphysics commercial software. The behaviors of the micro-plate and its package under mechanical shock are then investigated through the use of the linear shock spectrum together with the backbone curves of the system for the first time. Employing this approach, the critical shock durations, at which the influence of mechanical shock becomes extreme, as well as the internal resonances of the system, are obtained. The results reveal that decreasing the shock duration does not increase the influence of mechanical shock all the time. In addition, it is found that the occurrence of the one-to-one internal resonance, which can drastically increase the micro-plate deflections and provide an unexpected pull-in behavior, is not possible except for cases with very small micro-plate to package mass ratios. Furthermore, it is observed that the occurrence of the one-to-three internal resonance cannot put the micro-plate into a dangerous situation.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287330 Collegamento a IRIS

2021
Nonlinear vibrations of a composite beam in large displacements: Analytical, numerical, and experimental approaches
JOURNAL OF COMPUTATIONAL AND NONLINEAR DYNAMICS
Autore/i: Utzeri, M.; Sasso, M.; Chiappini, G.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: This paper investigates the nonlinear dynamic behavior of a cantilever beam made of composite material without and with lumped mass fixed along its length. The analysis compares the results coming from analytical and numerical modeling with experimental observations. The first part focuses on the analytical model. The model takes into account the nonlinearity derived from large amplitude vibration and inertia. The second part deals with the experimental test, where the specimen and the data acquisition are defined. Then, the nonlinearity of the acquired data is determined by the fitting time history (FTH) technique. The third part deals with the finite element model. Finally, the results obtained by the analytical method, the experimental method, and the numerical method are compared between each other.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/286637 Collegamento a IRIS

2021
Earthen claddings in lightweight timber framed buildings: An experimental study on the influence of fir boards sheathing and GFRP jacketing
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Serpilli, M.; Stazi, F.; Chiappini, G.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: The aim of this research was to investigate the mechanical performance of an earthen massive cladding, recently used for external/internal layers in Platform Frame technology, through an extensive experimental campaign. The masonry is built with extruded unbaked earth blocks and characterized by dovetail horizontally staggered bed joints. The wall is secured to the structural timber studs through 45 degree-angled fir boards sheathing panels, fixed with steel connectors, and finished with an external plaster with an embedded Glass Fibre Reinforced Polymer (GFRP) mesh, wrapping the whole masonry. The influence of the fir board panels and GFRP jacketing on the mechanical behavior of the earth blocks masonry is investigated and compared with the results obtained for the unreinforced configuration (bare wallettes) in (Stazi et al., 2020). The experimental program consisted of compression, diagonal compression and combined shear-compression tests on 18 wallettes. Digital Image Correlation technique was also adopted to investigate the full field strain maps. The results showed that under compression all the samples (with and without reinforcements) behave as a series of independent slender columns, without significant differences among reinforcement type. Both diagonal compression and shear with compression tests revealed the optimal behavior of GFRP plaster reinforcement that increases the strength values and thanks to an effective confinement effect, limits the out-of-plane bending and determines a monolithic response of the wall.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/288772 Collegamento a IRIS

2021
Time-delay dynamics of the MR damper–cable system with one-to-one internal resonances
NONLINEAR DYNAMICS
Autore/i: Peng, J.; Wang, L.; Zhao, Y.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: In this study, we investigate the nonlinear resonant response of a magnetorheological (MR) damper–stay cable system with time delay, and the one-to-one internal resonance is considered. Based on Hamilton’s principle, the motion equations of the MR damper–cable system are derived, and the Galerkin method is applied to obtain the discrete model. Then, the method of multiple scales is applied to determine the modulation equations and the second-order solution of the nonlinear response of the MR damper–cable system. Following, the equilibrium solution and dynamic solution of the modulation equations are examined via the Newton–Raphson method and shooting method. The results show that the equilibrium solution may undergo Hopf bifurcation, resulting in the periodic solution. Moreover, the effects of the time delay and the inclination angle on the resonant response of the MR damper–cable system are investigated as well as those of the damper position. The numerical results show that the time delay increases the amplitudes of in-plane and out-of-plane modes and results in the more remarkable hardening behavior and relatively poor mitigation performance of the MR damper. However, the large time delay may suppress the complex chaotic modulation motion of the MR damper–cable system.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/291396 Collegamento a IRIS

2021
Natural Frequencies And Internal Resonance Of Beams With Arbitrarily Distributed Axial Loads
JOURNAL OF APPLIED AND COMPUTATIONAL MECHANICS
Autore/i: Lenci, S.; Clementi, F.
Classificazione: 1 Contributo su Rivista
Abstract: An exact analytical solution for transversal free vibrations of a beam subjected to an arbitrary distributed axial load and a tip tension is obtained by means of a power series representation, whose coefficients are determined recursively in an easy way. The dependence on the natural frequencies on the load is then investigated, and the buckling load (corresponding to vanishing frequency) is also discussed. Next, the 1:3 internal resonance between the first and the second mode is deeply studied, and an interesting (and unexpected) property is found for linearly distributed axial loads
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/291395 Collegamento a IRIS

2021
Mode Coupling in Dynamic Atomic Force Microscopy
PHYSICAL REVIEW APPLIED
Autore/i: Chandrashekar, A.; Belardinelli, P.; Lenci, S.; Staufer, U.; Alijani, F.
Classificazione: 1 Contributo su Rivista
Abstract: Increasing the signal-to-noise ratio in dynamic atomic force microscopy plays a key role in nanomechanical mapping of materials with atomic resolution. In this work, we develop an experimental procedure for increasing the sensitivity of higher harmonics of an atomic-force-microscope cantilever without modifying the cantilever geometry but instead by utilizing dynamical mode coupling between its flexural modes of vibration. We perform experiments on different cantilevers and samples and observe that via nonlinear resonance frequency tuning we can obtain a frequency range where strong modal interactions lead to 7-fold and 16-fold increases in the sensitivity of the 6th and 17th harmonics while reducing sample indentation. We derive a numerical model that captures the observed physics and confirms that nonlinear mode coupling is the reason for the increase of the amplitude of higher harmonics during tip-sample interactions.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/288570 Collegamento a IRIS

2021
An experimental and numerical study on the in-plane axial and shear behavior of sprayed in-situ concrete sandwich panels
ENGINEERING STRUCTURES
Autore/i: Serpilli, Michele; Clementi, Francesco; Lenci, Stefano
Classificazione: 1 Contributo su Rivista
Abstract: The pa­per deals with the ex­per­i­men­tal and nu­mer­i­cal char­ac­ter­i­za­tion of the in-plane ax­ial and shear me­chan­i­cal be­hav­ior of sprayed in-situ re­in­forced con­crete (RC) sand­wich pan­els, used as struc­tural walls. Ax­ial com­pres­sion tests were car­ried out on spec­i­mens with dif­fer­ent slen­der­ness ra­tios to study their be­hav­ior un­der ax­ial ver­ti­cal loads. While the di­ag­o­nal com­pres­sion test and shear load with con­stant com­pres­sion test were re­spec­tively per­formed on squared pan­els, an­a­lyz­ing their re­sponse to in-plane hor­i­zon­tal lat­eral forces. Ul­ti­mate ax­ial and shear loads have been ex­per­i­men­tally de­ter­mined and the most sig­nif­i­cant load–dis­place­ment di­a­grams have been re­ported. The ob­tained re­sults have been com­pared with other ex­per­i­men­tal cam­paigns on RC sand­wich pan­els and with con­ven­tional RC walls equa­tions, avail­able in codes of prac­tice and lit­er­a­ture. The struc­tural po­ten­tial­i­ties of RC sand­wich pan­els as load-bear­ing and shear walls are high­lighted. The ex­per­i­men­tal in­ves­ti­ga­tion is cor­rob­o­rated by a 3D non­lin­ear fi­nite el­e­ment (FE) nu­mer­i­cal analy­sis, con­sid­er­ing the in­flu­ence of the in­su­la­tion layer, the ef­fi­ciency of steel con­nec­tors, and the in­volved ma­te­r­ial non­lin­ear­i­ties.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287329 Collegamento a IRIS

2021
Propagation of periodic waves in beams on a bilinear foundation
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
Autore/i: Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: The propagation of periodic flexural waves in an Euler-Bernoulli beam resting on a bilinear elastic foundation is investigated. Although the problem is nonlinear, the closed form solution is obtained thanks to its piecewise linear nature. The dependence of the phase velocity on the two stiffnesses of the substrated is investigated in depth, and it is shown that a very complex behaviour is observed when the stiffnesses are large. Veering-like phenomena has been discovered, apparently for the first time. It is shown that some branches end with cusp points, not related to classical bifurcations. The stability of the considered waves is also addressed, in a restricted class of perturbations.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/292564 Collegamento a IRIS

2021
Discontinuous approaches for nonlinear dynamic analyses of an ancient masonry tower
ENGINEERING STRUCTURES
Autore/i: Ferrante, A.; Loverdos, D.; Clementi, F.; Milani, G.; Formisano, A.; Lenci, S.; Sarhosis, V.
Classificazione: 1 Contributo su Rivista
Abstract: The aim of this paper is to present the development of discontinuous approaches to simulate the nonlinear dynamic behaviour of the civic clock tower of Rotella, in the province of Ascoli Piceno (Italy). The study involves the use of the Non-Smooth Contact Dynamics method implemented in the LMGC90© code, where sliding motions are governed by Signorini's impenetrability condition and dry-friction Coulomb's law, and the Discrete Element Method with cohesive and tensional behaviours at the joints in the 3DEC© code. The tower was represented using three different geometric models ranged from the most complex one, including the full geometry and multi-leaf masonry walls, to the simplest one, including the single-leaf walls as a simplification of the real masonry. The numerical results highlighted the modes of failure depending on the shape, size and texture of the masonry and the modalities of progressive damage under dynamic actions. Moreover, both numerical approaches have proven to be capable of simulating large displacements and complete block separations, reproducing complex mechanical behaviours and making predictions on the vulnerability assessment of the historical masonry buildings.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/286753 Collegamento a IRIS

2021
A Preliminary Validation of a New Surgical Procedure for the Treatment of Primary Bladder Neck Obstruction Using a Computational Modeling Approach
BIOENGINEERING
Autore/i: Serpilli, Michele; Zitti, Gianluca; Dellabella, Marco; Castellani, Daniele; Maranesi, Elvira; Morettini, Micaela; Lenci, Stefano; Burattini, Laura
Classificazione: 1 Contributo su Rivista
Abstract: A new surgical procedure for the treatment of primary bladder neck obstruction with maintenance of anterograde ejaculation is proposed. In place of monolateral or bilateral bladder neck incision, associated with a loss of ejaculation rate of up to 30%, the new surgical procedure consists of laser drilling the bladder neck with a number of holes and without muscle fiber disrup- tion. The effect of this novel procedure has been studied numerically, with a simplified two-dimen- sional numerical model of the internal urethral sphincter, varying the position and the number of holes in the fibrotic region of the urethral tissue. Results show an improvement of the urethral sphincter opening by increasing the number of holes, ranging from about 6% to 16% of recovery. Moreover, a non-aligned position of holes positively influences the opening recovery. The concen- trations of maximum principal strain and stress have been registered in the proximity of the inter- face between the physiologic and diseased sphincter, and in those regions where the radial thick- ness is significantly thinner. The effects on the first five patients have been included in the study, showing improvement in micturition, lower urinary tract symptoms, sustained ejaculatory func- tion, and quality of life.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/290912 Collegamento a IRIS

2021
Modelling of low-velocity impacts on composite beams in large displacement
FRATTURA E INTEGRITÀ STRUTTURALE
Autore/i: Utzeri, M.; Sasso, M.; Chiappini, G.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: The paper provides an evaluation of the nonlinear dynamic response of a cantilever beam made of composite material subjected to low-velocity impacts. The structure is assumed to respond in a quasi-static manner and modelled by a continuous beam in large displacement with a lumped mass attached. First, an analytical model was developed to study the free vibrations of a beam, taking into account the nonlinearities due to large displacements and inertia. Then, the analytical findings were compared with experimental test data. The vibration of a real composite beam has been acquired through high-speed imaging technique. The displacements of the beam were extracted by digital image analysis; then, the nonlinear parameters of the analytical model were determined by the Fitting Time History technique. The results obtained by the analytical model and the experimental test are compared with numerical analysis. The validated analytical model was adapted to study a low-velocity impact; the lumped mass was associated with a rigid projectile, whose initial speed represents the impact velocity.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/293482 Collegamento a IRIS

2020
Nonlinear vibrations of an extensional beam with tip mass in slewing motion
MECCANICA
Autore/i: Warminski, J.; Kloda, L.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: Dynamics of a rotor composed of a flexible beam attached to a slewing rigid hub is presented in the paper. Dynamics of the structure is studied for a slender beam model, based on extended Bernoulli–Euler theory, which takes into account a nonlinear curvature, coupled transversal and longitudinal oscillations and non-constant angular velocity of the hub. Moreover, to demonstrate a general case for dynamical boundary conditions, lumped mass fixed at the beam tip is added. The partial differential equations (PDEs) are derived from Hamilton principle of the least action. The analytical solutions of the PDEs are obtained by the multiple time scale method applied directly to PDEs. Forced vibrations around selected resonance zones are studied and the influence of beam rotation, preset angle, hub radius, tip mass is presented. Hardening and softening phenomena, respectively for the first and the second mode, are obtained for various angular velocity values.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/285556 Collegamento a IRIS

2020
Chaos in one-dimensional structural mechanics
NONLINEAR DYNAMICS
Autore/i: Rega, G.; Settimi, V.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: Notwithstanding the presence of some books summarizing specific research bodies on structural systems, reviews on nonlinear dynamics and chaos in mechanical systems and structures are quite few. This paper aims at giving a first contribution in this direction, focusing on chaos in one-dimensional structural mechanics, and reviewing fundamental studies and main outcomes obtained for macromechanical systems and applications in classical areas of mechanical, aeronautical and civil engineering. Research material is presented according to a tentatively comprehensive perspective, by suitably framing the overviewed complex dynamic phenomena of a given class of structures within the underlying continuous/reduced modelling context and the regular phenomena from which they ensue. This is a demanding perspective, which also entails leaving a number of important topics aside. Chaos in cable, beam/arch, and coupled cable-beam structures is reviewed, as highlighted in both engineering-oriented studies and theoretically driven ones, paying attention also to some relevant applications.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/285292 Collegamento a IRIS

2020
Modal localisation in a beam modelled as a continuous system: A discussion on the use of auxiliary oscillators
JOURNAL OF SOUND AND VIBRATION
Autore/i: Ribeiro, E. A. R.; Lenci, S.; Mazzilli, C. E. N.
Classificazione: 1 Contributo su Rivista
Abstract: In this work, we show that perfectly localised modal vibrations can be obtained in continuous linear elastic structures, provided that, in addition to the regular boundary and continuity/jump conditions, extra (admissibility) conditions are met. They are derived with the aid of: (i) new parameters and/or DOFs of auxiliary systems, and/or (ii) admissible relationships amongst the original structural parameters. In both cases, however, the solution resorts to a fine-tuning problem. To illustrate the main ideas, we discuss three examples: two simply-supported beams with cantilever extensions and attached lumped oscillators, and a “tuning-fork-like” structure. Finally, to show that there are also systems in which fine-tuning is not possible, we discuss the case of two lumped oscillators attached to the free end of a cantilever beam.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/285291 Collegamento a IRIS

2020
An impact model of a ball bouncing on a flexible beam
MECCANICA
Autore/i: Demeio, L.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: In this work we investigate a model for the description of the impact of a ball with a flexible beam. The coupling of the kinematic parameters of the ball (the velocity components) with the vibration modes of the beam are taken into account by using the Hertz theory of impact. We solve the model equations numerically in a few physically relevant cases and illustrate the variation of the modal coefficients of the beam and of the velocity components of the ball during the impact. The restitution coefficient, the size of the deformation region and the impact duration are also reported as functions of the impact velocity and of the impact location.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/285290 Collegamento a IRIS

2020
A detailed study of the parametric excitation of a vertical heavy rod using the method of multiple scales
MECCANICA
Autore/i: Vernizzi, G. J.; Lenci, S.; Rosa Franzini, G.
Classificazione: 1 Contributo su Rivista
Abstract: An analytical solution for the problem of an immersed flexible and vertical heavy rod subjected to a vertical top motion is developed using the multiple scales method directly applied to the partial differential equations of motion. The obtained results show good agreement with a numerical solution obtained using the finite element method for a study case. The analytical solution is then used to carry out some sensitivity studies. The effects of the structural nonlinearities, hydrodynamic and structural damping terms are investigated. It is shown that the nonlinearities play a role in defining the frequency of the top motion that causes the maximum amplitude of response, but not the value of the amplitude itself. In turn, the major role played by the hydrodynamic damping in defining the response amplitude is addressed. It is also shown that the structural damping have an important effect on the response amplitude even in the case of small damping ratio. This occurs due to the combined effect of the structural with the hydrodynamic damping. Finally, it is pointed out that small differences in the structural damping ratio can lead to significant differences in the response amplitude.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/285658 Collegamento a IRIS

2020
The modelling of multiple leaf masonry walls of the arquata del tronto fortress as a non-smooth dynamical system
Proceedings of the International Conference on Structural Dynamic , EURODYN
Autore/i: Ferrante, A.; Giordano, E.; Clementi, F.; Sarhosis, V.; Milani, G.; Lenci, S.
Editore: European Association for Structural Dynamics
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: In the present paper has been reported the Non-Smooth Contact Dynamics method (NSCD) used for the damage evaluation of the multiple leaf masonry walls of the medieval fortress of Arquata del Tronto, strongly affected by the last Centre Italy earthquakes of August and October 2016. Pursuing this approach, a system of rigid blocks has been used for the assembly of the masonry structure. By means of contacts between blocks, which are governed by the Signorini's impenetrability condition and by dry-friction Coulomb's law, the building exhibits discontinuous dynamics. Finally, the NSCD method has proved to be an effective instrument for investigating the dynamical behaviour of the masonry structures under the ground seismic accelerations. Indeed, several possible failure mechanisms have been confirmed through the numerical results, which have given a deep insight into the seismic vulnerability of this damaged medieval fortress.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287437 Collegamento a IRIS

2020
Damage assessment of churches in the city of camerino after the 2016 central Italy seismic sequence
Proceedings of the International Conference on Structural Dynamic , EURODYN
Autore/i: Giordano, E.; Ferrante, A.; Clementi, F.; Lenci, S.
Editore: European Association for Structural Dynamics
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: In the present work, the importance of considering the exact nonlinear and three-dimensional behavior of masonry structures is shown, in order to highlight all the structural deficiencies of different churches damaged by the last Centre Italy earthquake in the city of Camerino. For this purpose, the exact geometries of the structures are reconstructed, while information regarding the mechanical properties of masonry material are derived from previous investigations and literature references. Based on this information, different numerical models are used to reconstruct the damages. Different three-dimensional FE models, endowed with an elastic plastic (softening) damage constitutive law, are adopted to determine the seismic vulnerability of the building by means of nonlinear static analyses using the smeared fracture energy approach. With this method it is possible to establish, with a right degree of approximation, the areas where the most important cracks are expected and, in general, the location of the potential damage caused by horizontal forces.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287433 Collegamento a IRIS

2020
Modal parameters identification on environmental testd of ancient bell towers and validation of their numerical models
Proceedings of the International Conference on Structural Dynamic , EURODYN
Autore/i: Clementi, F.; Standoli, G.; Giordano, E.; Ferrante, A.; Lenci, S.
Editore: European Association for Structural Dynamics
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Masonry towers are quite widespread in Europe and represent an important portion of the built heritage that must be preserved, especially in high-seismicity regions. Very often, such masonry towers exhibit unique peculiar morphologic and typological characteristics, which might affect their different structural behaviors under horizontal loads. For this reason, accurate knowledge of their dynamical parameters is useful for seismic assessment and the design of risk mitigation interventions. In this work, the opportunities provided by dynamic identification techniques for the non-destructive evaluation of heritage structures are discussed with a focus on different bell towers, located in the Marche region (Italy). All of them were stricken by a long seismic sequence (Center Italy earthquakes between August and October 2016), and are investigated in detail in order to have an insight into their dynamic behavior. Furthermore, the experimental investigations and the operational modal analysis results are presented, and they are useful for defining the Finite Element (FE) model of the towers with a continuum approach. The monitoring system consists of several elements adequately connected. Many operative problems have conditioned the positioning of the instrumentation due to the limited accessibility of the structure, not only to the primary access but also to reach the top. However, it has been possible to identify with certain confidence the first three frequencies of the towers and their corresponding mode shapes. The results carried out after the updating procedure may be considered very good. The material data values estimated in this way will constitute an important reference for the evaluation of the state of the building.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287434 Collegamento a IRIS

2020
Experimental study of the mechanical behaviour of a new extruded earth block masonry
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: STAZI, Francesca; SERPILLI, Michele; CHIAPPINI, GIANLUCA; PERGOLINI, MARIANNA; FRATALOCCHI, Evelina; LENCI, Stefano
Classificazione: 1 Contributo su Rivista
Abstract: The aim of this research is to investigate, through the Digital Image Correlation (DIC) technique, the mechanical performance of a new type of earth masonry, built with extruded blocks and characterized by dovetail horizontally staggered bed joints. The experimental program consists of two levels of investigations: (i) preliminary phase on components, (ii) compression, diagonal compression and combined shear-compression tests on 12 wallettes. Regarding the components, results showed that the mean compressive strength of the earth block was low (3.5 MPa) with respect to traditional bricks and similar to adobe blocks. The dovetail joints were effective in their joining role showing a rather good strength (2.4 MPa) when tested in triplet configuration. Regarding the wallettes, the DIC highlighted failure modes complying with the ones of a traditional masonry under shear, while it showed a ‘‘column behaviour” with vertical sliding under compressive tests. Fragile failures occurred during the diagonal compression test. DIC revealed to be a promising technique to recover the full-field strain and crack maps.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/276215 Collegamento a IRIS

2020
Aftershock fragility assessment of Italian cast–IN–place RC industrial structures with precast vaults
JOURNAL OF BUILDING ENGINEERING
Autore/i: Poiani, Marina; Gazzani, Valentina; Clementi, Francesco; Lenci, Stefano
Classificazione: 1 Contributo su Rivista
Abstract: Through a fragility analysis carried out with different probabilistic methods, the vulnerability of an Italian cast-in-place RC industrial structure with precast reinforced hollow brick light-weight vaults is evaluated via nonlinear analyses. After a brief description of the vault construction system, a typical case study built in the 1960s is considered and the influence of FE numerical modelling through three different representations of the vault system is assessed. Fragility curves are calculated by Incremental Dynamic Analysis (IDA), with three damage limit threshold values corresponding to local limit conditions regarding bending or shear that first occur in a few elements, as determined through pushover analyses. A comparison of fragility curves in the two horizontal directions (X–Y) for the three models is reported. Concerning the model with the greatest probability of collapse, seismic sequence effects on structural damage with the same ground motions for mainshock and aftershock are taken into account. Double Incremental Dynamic Analysis (D-IDA), with the mainshock represented by several fixed percentages of Near Collapse PGAs previously evaluated in X–Y directions and scaled aftershocks, is performed and compared to the IDA results. Aftershock fragility curves created with only the damage limit threshold value of Near Collapse are likened to the case that analyses a single seismic event (undamaged structure). Furthermore, ductility damage indices are calculated for maximum displacements obtained by each nonlinear dynamic analysis of IDA and D-IDA.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/273195 Collegamento a IRIS

2020
Crumbling of Amatrice clock tower during 2016 Central Italy seismic sequence: Advanced numerical insights
FRATTURA E INTEGRITÀ STRUTTURALE
Autore/i: Clementi, F.; Milani, G.; Ferrante, A.; Valente, M.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: The dynamic behaviour and the seismic vulnerability of the ancient civic tower of Amatrice, dramatically damaged by the last shocks sequence of 2016 that occurred in Central Italy, have been studied in this paper by means of advanced 3D numerical analyses with the Discrete Element Method (DEM). Thus, a discontinuous approach has been used to assess the dynamic properties and the vulnerability of the masonry structure, through large deformations regulated by the Signorini’s law, concerning the impenetrability between the rigid bodies, and by the Coulomb’s law, regarding the dry-friction model. Afterward, different values have been assigned to the friction coefficient of the models and real seismic shocks have been applied in the nonlinear analyses. The major purpose of this study is to highlight that relevant data on the real structural behaviour of historical masonry can be provided through advanced numerical analyses. The comparison between the results of the numerical simulation and the survey of the existing crack pattern of the bell tower permitted to validate the approach used. Finally, from the results and conclusions of this case study, it is possible to affirm that the used methodology can be applied to a wide variety of historical masonry structure in Europe.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/272571 Collegamento a IRIS

2020
The Non-smooth Dynamics of Multiple Leaf Masonry Walls of the Arquata Del Tronto Fortress
Proceedings of XXIV AIMETA Conference 2019
Autore/i: Clementi, Francesco; Ferrante, Angela; Lenci, Stefano
Editore: Springer
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The progressive damage of the multiple leaf masonry walls of the Arquata del Tronto medieval fortress, inside the epicentral zone of the last Centre Italy earthquakes of August and October 2016, has been investigated by means of the Non-Smooth Contact Dynamics method (NSCD). According to this model, the masonry structure has been modelled as a system of rigid blocks, and since the contacts between blocks are governed by the Signorini’s impenetrability condition and by dry-friction Coulomb’s law, the building exhibits discontinuous dynamics. The NSCD method has proved to be a powerful tool for investigating the dynamics induced by ground seismic accelerations. Indeed, the numerical results have given a deep insight into the seismic vulnerability of this damaged medieval fortress, confirming several possible failure mechanisms.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/275745 Collegamento a IRIS

2020
Damage assessment of ancient masonry churches stroked by the Central Italy earthquakes of 2016 by the non-smooth contact dynamics method
BULLETIN OF EARTHQUAKE ENGINEERING
Autore/i: Clementi, F.; Ferrante, A.; Giordano, E.; Dubois, F.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: The non-smooth contact dynamics method was selected to investigate the damage occurred to typical masonry churches (namely Apennine churches) belonging to Central Italy areas affected by the seismic activity started in 2016. The investigated buildings show discontinuous dynamics since the optioned method gave the chance to properly model the temples as multi rigid body systems using the Signorini’s impenetrability condition and the dry-friction Coulomb’s law, achieving a thoughtful response to ground seismic solicitations. The results provided by the assessment grant an overview of the most common damages and failure mechanisms, giving the guidelines to restoration projects that fully respond to structural needs.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/264833 Collegamento a IRIS

2020
A Genetic Algorithm Procedure for the Automatic Updating of FEM Based on Ambient Vibration Tests
SENSORS
Autore/i: Bianconi, F.; Salachoris, G. P.; Clementi, F.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: The dynamic identification of the modal parameters of a structure, in order to gain control of its functionality under operating conditions, is currently under discussion from a scientific and technical point of views. The experimental observations obtained through structural health monitoring (SHM) are a useful calibration reference of numerical models (NMs). In this paper, the procedures for the identification of modal parameters in historical bell towers using a stochastic subspace identification (SSI) algorithm are presented. Then, NMs are manually calibrated on the identification’s results. Finally, the applicability of a genetic algorithm for the automatic calibration of the elastic parameters is considered with the aim of searching for the properties of the autochthonous material, in order to reduce modelling error following the model assurance criterion (MAC). In this regard, several material values on the same model are examined to see how to approach the evolution and the distribution of these features, comparing the characterization proposed by the genetic algorithm with the results considered by the manual iterative procedure.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/282515 Collegamento a IRIS

2020
Flexural wave propagation in infinite beams on a unilateral elastic foundation
NONLINEAR DYNAMICS
Autore/i: Lenci, S.; Clementi, F.
Classificazione: 1 Contributo su Rivista
Abstract: The problem of flexural wave propagation on a beam resting on a unilateral elastic substrate is addressed. The Euler–Bernoulli beam theory, which is valid for slender beams and for large enough wave length, is used. The governing equations are recalled, and the boundary conditions corresponding to the “single wave” periodic solutions are determined. The ensuing system of three algebraic transcendental equations is solved, and the exact solution of the problem is provided, in spite of the nonlinearity due to the piecewise behavior of the soil. The wave velocity as function of the foundation stiffness is obtained and compared with the classical case of the bilateral foundation. The main wave propagation properties are discussed, and some of them are illustrated with graphs reporting wave shapes.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/265852 Collegamento a IRIS

2020
Hardening vs. softening dichotomy of a hinged-simply supported beam with one end axial linear spring: Experimental and numerical studies
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
Autore/i: Kloda, L.; Lenci, S.; Warminski, J.
Classificazione: 1 Contributo su Rivista
Abstract: The aim of this paper is to validate experimentally a nonlinear model of a kinematically excited hinged-simply supported beam with a spring subjected to one end. An experimental setup configuration enables to test different variants of axial boundary conditions: first a typical simply supported beam (no spring), and next two different spring systems. The prototype is kinematically excited with different amplitudes of excitation and then full frequency response curves are drawn wherein hardening/softening dichotomy is recognized. A set of mechanical properties of the system is identified and then used to reproduce tests with finite element simulations. Consequently numerical vs. experiment results are compared. The analysis demonstrates amplitude dependent damping as well as that the natural frequency depends on environmental conditions, and thus may change over experiments.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/283224 Collegamento a IRIS

2020
1:1 internal resonance in a two d.o.f. complete system: a comprehensive analysis and its possible exploitation for design
MECCANICA
Autore/i: Clementi, F.; Lenci, S.; Rega, G.
Classificazione: 1 Contributo su Rivista
Abstract: The internal resonance of a two degree-of-freedom mechanical system with all typical (quadratic and cubic) geometric nonlinearities is studied, limiting to the case of free dynamics. The Multiple Time Scale method is used to provide an analytical, closed form, approximation of the backbone curves. The cornucopia of different possible behaviours that can been obtained by varying the nonlinear stiffnesses is discussed in depth, illustrating them with some examples and verifying with numerical simulations. Some partially unexpected or relevant behaviours are highlighted, and some hints on how to exploit the proposed results to design nonlinearly tailored systems are given.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/280902 Collegamento a IRIS

2020
Longitudinal–transversal internal resonances in Timoshenko beams with an axial elastic boundary condition
NONLINEAR DYNAMICS
Autore/i: Lenci, S.; Clementi, F.; Kloda, L.; Warminski, J.; Rega, G.
Classificazione: 1 Contributo su Rivista
Abstract: The internal resonances between the longitudinal and transversal oscillations of a forced Timoshenko beam with an axial end spring are studied in depth. In the linear regime, the loci of occurrence of 1 : ir, ir∈ N, internal resonances in the parameters space are identified. Then, by means of the multiple time scales method, the 1 : 2 case is investigated in the nonlinear regime, and the frequency response functions and backbone curves are obtained analytically, and investigated thoroughly. They are also compared with finite element numerical simulations, to prove their reliability. Attention is paid to the system response obtained by varying the stiffness of the end spring, and it is shown that the nonlinear behaviour instantaneously jumps from hardening to softening by crossing the exact internal resonance value, in contrast to the singular (i.e. tending to infinity) behaviour of the nonlinear correction coefficient previously observed (without properly taking the internal resonance into account).
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/283809 Collegamento a IRIS

2020
Damage assessment of san francesco church in amandola hit by central Italy 2016-2017 seismic event
AIP Conference Proceedings
Autore/i: Giordano, E.; Ferrante, A.; Ribilotta, E.; Clementi, F.; Lenci, S.
Editore: American Institute of Physics Inc.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Italy is a high seismic risk country. Since 1900 more than 30 earthquakes with magnitude greater than Mw=5.8 occurred, and the last one is the Central Italy seismic sequence. The first shock aroused in the 24th August (Mw=6.2) followed by another stronger quake in the 30th October (Mw=6.5). It heavily hit the regions of Marche, Umbria, and Abruzzo causing many deaths, injuries and extensive damages on the cultural heritage. This paper analyses the church of San Francesco in Amadola, located in the Marche region that has been considered condemned for the severe damages reported after these earthquakes. The church is globally analyzed by the application of nonlinear static analysis on a Finite Element Model where the nonlinearity of masonry is taking into account with a proper constitutive law. The study wants to prove how global analysis combined by the local analysis can reproduce the behavior of this structure during a quake, showing that it can repeat the real damages produced by earthquakes.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287432 Collegamento a IRIS

2020
Advanced seismic analyses of "Apennine churches" stroked by the central Italy earthquakes of 2016 by the non-smooth contact dynamics method
AIP Conference Proceedings
Autore/i: Ferrante, A.; Ribilotta, E.; Giordano, E.; Clementi, F.; Lenci, S.
Editore: American Institute of Physics Inc.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The dynamic behaviour and the seismic vulnerability of different masonry "Apennine Churches". dramatically damaged by the last shocks sequence of 2016 that occurred in Central Italy, have been studied in this paper by means of advanced 3D numerical analyses with the Discrete Element Method (DEM). Thus, a discontinuous approach has been used to assess the dynamic properties and the vulnerability of the masonry structure, through large deformations regulated by the Signorini's law, concerning the impenetrability between the rigid bodies, and by the Coulomb's law, regarding the dry-friction model. The major purpose of this study is to highlight that relevant data on the real structural behaviour of historical masonry can be provided through advanced numerical analyses. The comparison between the results of the numerical simulation and the survey of the existing crack pattern of the churches permitted to validate the used approach. Finally, from the results and conclusions of these cases study, it is possible to affirm that the used methodology can be applied to a wide variety of historical masonry structure in Europe.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287431 Collegamento a IRIS

2020
Tracking modal parameter evolution ofdifferent cultural heritage structures damaged by central Italy earthquake of 2016
AIP Conference Proceedings
Autore/i: Ribilotta, E.; Giordano, E.; Ferrante, A.; Clementi, F.; Lenci, S.
Editore: American Institute of Physics Inc.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The preliminary results of an ambient-vibration based investigation conducted on a large sample of historic masonry towers in the Marche region (Central Italy) are presented, with a focus on the belfry of Collegiata of Santa Maria in Visso (Italy). The assessment procedure includes full-scale ambient vibration testing, ambient modal identification, finite element modeling and dynamic-based identification of the uncertain structural parameters of the model. As the most doubtful parameters, the modulus of elasticity of the masonry is adjusted to achieve the experimental results with numerical model by simple operations.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287430 Collegamento a IRIS

2019
IUTAM Symposium on Exploiting Nonlinear Dynamics for Engineering Systems
IUTAM Symposium on Exploiting Nonlinear Dynamics for Engineering Systems
Autore/i: Kovacic, I.; Lenci, S.
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269318 Collegamento a IRIS

2019
Diagnostic survey on frescoes paintings in Pompei by active Ir-thermography
IMEKO International Conference on Metrology for Archaeology and Cultural Heritage, MetroArchaeo 2017
Autore/i: Castellini, P.; Martarelli, M.; Lenci, S.; Quagliarini, E.; Silani, M.; Martellone, A.
Editore: International Measurement Confederation (IMEKO)
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/272664 Collegamento a IRIS

2019
Damage survey and advanced seismic analyses of different masonry churches after the central Italy earthquake of 2016
COMPDYN 2019 Proceedings
Autore/i: Clementi, F.; Giordano, E.; Ferrante, A.; Lenci, S.
Editore: National Technical University of Athens
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This study presents a detailed failure analysis of different masonry churches, which were severely damaged during the 2016 Centre of Italy seismic sequence, using nonlinear (i.e., kinematic limit and pushover) analyses. The main aims of the numerical investigations are: (i) to carry out a sufficiently wide sensitivity study on different specific case studies to have an insight into the role played by the geometry - which is always unique for churches - and by the irregularities; (ii) to validate or address the limits of applicability of the most widespread conventional static approaches recommended by Italian Code.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/274950 Collegamento a IRIS

2019
Sustainable Engineering for Resilient Built and Natural Environments
The First Outstanding 50 Years of “Università Politecnica delle Marche”
Autore/i: Alici, Antonello; Bocci, Maurizio; Bonvini, Paolo; Brocchini, Maurizio; Calamai, Alessandro; Canestrari, Francesco; Capozucca, Roberto; Carbonari, Alessandro; Carbonari, Sandro; Cardone, Fabrizio; Clementi, Francesco; Clini, Paolo; Cocchi, Giammichele; Corvaro, Sara; Darvini, Giovanna; Davì, Fabrizio; Dezi, Luigino; Di Giuseppe, Elisa; D’Orazio, Marco; Ferretti, Maddalena; Ferrotti, Gilda; Gara, Fabrizio; Giretti, Alberto; Graziani, Andrea; Lancioni, Giovanni; Lemma, Massimo; Lenci, Stefano; Lorenzoni, Carlo; Malinverni, Eva Savina; Mancinelli, Alessandro; Mariano, Fabio; Mentrasti, Lando; Mondaini, Gianluigi; Montecchiari, Piero; Munafò, Placido; Naticchia, Berardo; Postacchini, Matteo; Quagliarini, Enrico; Quattrini, Ramona; Ragni, Laura; Serpilli, Michele; Soldini, Luciano; Virgili, Amedeo; Zampini, Giovanni
Editore: Springer
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/272866 Collegamento a IRIS

2019
Influence of transient escape and added load noise on the dynamic integrity of multistable systems
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
Autore/i: Orlando, Diego; Gonçalves, Paulo B.; Rega, Giuseppe; Lenci, Stefano
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/265401 Collegamento a IRIS

2019
Damage assessment by the non-smooth contact dynamics method of the iconic crumbling of the clock tower in Amatrice after the 2016 Central Italy seismic sequence
Proceedings of the International Conference on Numerical Analysis and Applied Mathematics 2018, ICNAAM 2018
Autore/i: Clementi, F.; Milani, G.; Gazzani, V.; Poiani, M.; Lenci, S.
Editore: American Institute of Physics Inc.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The dynamics of the medieval civic clock tower of Amatrice (Rieti-Italy) has been studied using the Non-Smooth Contact Dynamics (NSCD) method, implementing a discrete element numerical model in the LMGC90© code. Schematised as a system of rigid blocks, undergoing frictional sliding and plastic impacts, the tower has exhibited complex dynamics, because of the geometrical non-linearity and the non-smooth nature of the contact laws. Numerical simulations are performed with the aim of comparing the numerical result and the observed damages after the seismic sequence of the Central Italy earthquakes.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269306 Collegamento a IRIS

2019
Evaluation of different approaches for the seismic vulnerability assessment of RC structures
Proceedings of the International Conference of Computational Methods in Sciences and Engineering 2019, ICCMSE 2019
Autore/i: Gazzani, Valentina; Poiani, Marina; Clementi, Francesco; Pace, Giuseppe; Lenci, Stefano
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The seismic vulnerability of school buildings located in the municipality of Trecastelli (Marche, Central Italy) is evaluated with three different numerical models: the lumped plasticity, the distributed plasticity (fibre) and the 3D Continuum FE approaches. Nonlinear static (pushover) analyses are performed to assess the global seismic behaviour of the structures, and the limitations in the representativeness respect to the reality of different approaches are analysed
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/272691 Collegamento a IRIS

2019
Reduced-order models for the analysis of a vertical rod under parametric excitation
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
Autore/i: Vernizzi, G. J.; Franzini, G. R.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/273243 Collegamento a IRIS

2019
Global dynamics and integrity of a micro-plate pressure sensor
COMMUNICATIONS IN NONLINEAR SCIENCE & NUMERICAL SIMULATION
Autore/i: Belardinelli, P.; Sajadi, B.; Lenci, S.; Alijani, F.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/262764 Collegamento a IRIS

2019
Comparative fragility methods for seismic assessment of masonry buildings located in Muccia (Italy)
JOURNAL OF BUILDING ENGINEERING
Autore/i: Chieffo, N.; Clementi, F.; Formisano, A.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: The current paper focuses on a sector of the historic centre of Muccia, in the district of Macerata (Italy), affected by the seismic sequence that involved Central Italy in 2016. The main goal is comparison, in terms of fragility curves, among two vulnerability assessment methodologies (empirical and mechanical). The study area has been structurally and typologically identified according to the Building Typology Matrix (BTM). Physical vulnerability analysis of the urban-sector was performed through application of an index-based method, specifically for masonry building aggregates. An isolated masonry building, damaged after the seismic sequences, has been selected as a case study. For the assessed building, empirical fragility curves are presented according to Guagenti & Petrini’s correlation law. Furthermore, a numerical model has been set up by using the macro-element approach, which has allowed to perform non-linear static analyses. Mechanical properties of masonry were defined according to the New Technical Codes for Constructions (NTC18), assuming a limited knowledge level (LC1). Refined mechanical fragility functions have been derived and compared to the empirical ones. Analysis results have shown that the empirical method tends to overestimate by 5% and 10% the expected damage for slight and moderate thresholds. For PGA values greater than 0,3 g the damage levels decreased by 30% and 20%, with reference to the near collapse and collapse conditions, respectively.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/267525 Collegamento a IRIS

2019
Damage Assessment of San Francesco Church in Amandola Hit by Central Italy 2016-2017 Seismic Event
Mechanics of Masonry Structures Strengthened with Composite Materials III
Autore/i: Giordano, Ersilia; Ferrante, Angela; Ribilotta, Elisa; Clementi, Francesco; Lenci, Stefano
Editore: Trans Tech Publications Ltd
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Italy is a high seismic risk country since 1900 more than 30 earthquakes with magnitude greater than Mw=5.8 have occurred, and the last one is the Central Italy seismic sequence. The first shock occurred in the 24 August (Mw=6.2) followed by another stronger quake in the 30th October (Mw=6.5). It hit the regions of Marche, Umbria, and Abruzzo heavily causing many deaths, injuries and extensive damages on the cultural heritage. This paper analyses the church of San Francesco in Amadola, located in the Marche region that has been considered condemned for the severe damages reported after these earthquakes. The church is globally analyzed by the application of nonlinear static analysis on a Finite Element Model where the nonlinearity of masonry is taking into account with a proper constitutive law. The study wants to prove how global analysis combined by the local analysis can reproduce the behavior of this structure during a quake, showing that it can repeat the real damages produced by earthquakes.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269332 Collegamento a IRIS

2019
Advanced Seismic Analyses of “Apennine Churches” Stroked by the Central Italy Earthquakes of 2016 by the Non-Smooth Contact Dynamics Method
Mechanics of Masonry Structures Strengthened with Composite Materials III
Autore/i: Ferrante, Angela; Ribilotta, Elisa; Giordano, Ersilia; Clementi, Francesco; Lenci, Stefano
Editore: Trans Tech Publications Ltd
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The dynamic behaviour and the seismic vulnerability of different masonry “Apennine Churches”, dramatically damaged by the last shocks sequence of 2016 that occurred in Central Italy, have been studied in this paper by means of advanced 3D numerical analyses with the Discrete Element Method (DEM). Thus, a discontinuous approach has been used to assess the dynamic properties and the vulnerability of the masonry structure, through large deformations regulated by the Signorini’s law, concerning the impenetrability between the rigid bodies, and by the Coulomb’s law, regarding the dry-friction model. The major purpose of this study is to highlight that relevant data on the real structural behaviour of historical masonry can be provided through advanced numerical analyses. The comparison between the results of the numerical simulation and the survey of the existing crack pattern of the churches permitted to validate the used approach. Finally, from the results and conclusions of these cases study, it is possible to affirm that the used methodology can be applied to a wide variety of historical masonry structure in Europe.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269329 Collegamento a IRIS

2019
Characterising interfaces for reinforced concrete: Experiments and multiplane cohesive zone modelling for titanium alloy rebars
EUROPEAN JOURNAL OF MECHANICS. A, SOLIDS
Autore/i: Maracci, D.; Alfano, G.; Serpieri, R.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/268443 Collegamento a IRIS

2019
Damage Assessment by Numerical Modeling of Sant'Agostino's Sanctuary in Offida During the Central Italy 2016–2017 Seismic Sequence
FRONTIERS IN BUILT ENVIRONMENT
Autore/i: Giordano, Ersilia; Clementi, Francesco; Nespeca, Andrea; Lenci, Stefano
Classificazione: 1 Contributo su Rivista
Abstract: The subject of this work is the Sant'Agostino Sanctuary in Offida (Italy); we investigated both the dynamic behavior and the seismic vulnerability of the complex, used nowadays in its parts as school building, oratory, and church. Offida is in central Italy; the village has been severely damaged by the last seismic events of 2016. The sanctuary was heavily damaged by the earthquake of 24 August 2016. We recurred to finite elements to estimate the vulnerability of the sanctuary and its dynamic response, considering masonry's non-linear behavior by means of proper constitutive assumptions. To estimate how the monastery bears the lateral loads related to the expected demands resulting from seismic actions (N2 method) using non-linear static analysis (Pushover), we recurred to a homogenized material and smeared cracking and crushing constitutive law. As may be remarked by observing buildings that share the same features of the sanctuary and, moreover, by comparing seismic demand vs. capacity, the structure is prone to massive damage leading to collapse. The paper underlines how advanced numerical analysis grants fundamental data on how historical masonry buildings behave under seismic action, providing a method that may easily be implemented at historic monasteries in Europe.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/262744 Collegamento a IRIS

2019
Mechanical characterization of unfired earth via numerical assessment of the experimental data
Proceedings of the International Conference on Numerical Analysis and Applied Mathematics 2018, ICNAAM 2018
Autore/i: Clementi, Francesco; Cocchi, Giammichele; Lenci, Stefano
Editore: American Institute of Physics Inc
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The current work presents the first results on the determination of reliable numerical models of earthen blocks under different loading conditions. Uniaxial compression and 3-points bending tests were performed. Experimental behavior was modelled with a nonlinear model able to describe the cracking behavior. The simplified approach based on macro-modelling shows a satisfactory accuracy and low computational costs. The numerical results are in good agreement with the post-elastic behavior observed in the experimental campaign
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269304 Collegamento a IRIS

2019
Can textile reinforced mortar (TRM) systems be really effective to increase compressive strength of masonry panels?
Key Engineering Materials
Autore/i: Donnini, J.; Maracchini, G.; Chiappini, G.; Corinaldesi, V.; Quagliarini, E.; Lenci, S.
Editore: Trans Tech Publications Ltd
Classificazione: 2 Contributo in Volume
Abstract: The use of Textile Reinforced Mortar (TRM) systems represent a valid alternative to traditional strengthening techniques, to improve mechanical strength and seismic performance of masonry buildings. Their effectiveness has been validated by several studies [1-4]. However, the TRM contribution in the mechanical behavior of masonry walls, subjected to simple compression, has not yet been fully investigated. In this study, an experimental campaign with the objective of studying the efficiency of TRM systems, applied to clay brick masonry panels, is presented. Compression tests were conducted on clay brick masonry panels with dimensions of 250x1000x1200 mm3 . Glass fiber bidirectional fabrics were applied on both sides of the panels, coupled with lime-based mortar, and connected with stainless steel helical connectors. The total thickness of the reinforcement system is 30 mm. The effect of the TRM reinforcement on the mechanical behavior of the panel is analyzed and experimental results are compared with those of unreinforced panels in terms of ultimate strength and failure modes.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/270983 Collegamento a IRIS

2019
Tracking Modal Parameter Evolution of Different Cultural Heritage Structure Damaged by Central Italy Earthquake of 2016
Mechanics of Masonry Structures Strengthened with Composite Materials III
Autore/i: Ribilotta, Elisa; Giordano, Ersilia; Ferrante, Angela; Clementi, Francesco; Lenci, Stefano
Editore: Trans Tech Publications Ltd
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The preliminary results of an ambient-vibration based investigation conducted on a large sample of historic masonry towers in the Marche region (Central Italy) are presented, with a focus on the belfry of Collegiata of Santa Maria in Visso (Italy). The assessment procedure includes full-scale ambient vibration testing, modal identification from ambient vibration responses, finite element modeling and dynamic-based identification of the uncertain structural parameters of the model. As the most doubtful parameters, the modulus of elasticity of the masonry is adjusted to achieve the experimental results with numerical model by simple operations.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269330 Collegamento a IRIS

2019
Dynamic analysis of a ball bouncing on a flexible beam
JOURNAL OF SOUND AND VIBRATION
Autore/i: Demeio, L.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/262765 Collegamento a IRIS

2019
Influence of geometric nonlinearities on the asynchronous modes of an articulated prestressed slender structure
JOURNAL OF VIBRATION AND ACOUSTICS
Autore/i: Ribeiro, Eduardo A. R.; Mazzilli, Carlos E. N.; Lenci, Stefano
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/264671 Collegamento a IRIS

2019
Six-dimensional basins of attraction computation on small clusters with semi-parallelized SCM method
INTERNATIONAL JOURNAL OF DYNAMICS AND CONTROL
Autore/i: Andonovski, N.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/273244 Collegamento a IRIS

2019
Basins of Attraction for Higher-Dimensional Nonlinear Dynamical Systems: Preliminary Results on the Case Study of a Sympodial Tree
IUTAM Symposium on Exploiting Nonlinear Dynamics for Engineering Systems
Autore/i: Andonovski, Nemanja; Lenci, Stefano; Kovacic, Ivana
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269315 Collegamento a IRIS

2019
Tracking modal parameters evolution of a school building during retrofitting works
BULLETIN OF EARTHQUAKE ENGINEERING
Autore/i: Pierdicca, Alessio; Clementi, Francesco; Fortunati, Andrea; Lenci, Stefano
Classificazione: 1 Contributo su Rivista
Abstract: During a seismic improvement intervention that lasted more than one year, a reinforced concrete (RC) school building had been surveyed through dynamic monitoring, granting continuous updates on its global response. Operational Modal Analysis (OMA) was carried out to have a proper understanding of the structure’s dynamic evolution, using a Finite Element Model (FEM) to perform a non-invasive and quantitative structural assessment taking into account the interactions with the surroundings. During the whole restoration works, the long-term (periodic) monitoring campaign showed the increment of the building performance remarked by the variation of natural frequencies. Also, the experimental assessment of the influence of infill masonry panels on the dynamics of RC frame is shown at each upgraded configuration. Additional restoration works, that may eventually occur, could benefit from the data collected during the present Ambient Vibration Survey (AVS), providing useful parameters to enhance the retrofitting and the dynamic behavior of the structure.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/260611 Collegamento a IRIS

2019
An Overview of the Structural Safety-Oriented Research in the Region Marche Seismic Area
The First Outstanding 50 Years of “Università Politecnica delle Marche”
Autore/i: Capozucca, R.; Carbonari, S.; Clementi, F.; Cocchi, G.; Davi, F.; Dezi, L.; Gara, F.; Lancioni, G.; Lenci, S.; Mentrasti, L.; Ragni, L.; Serpilli, M.
Editore: Springer, Cham
Classificazione: 2 Contributo in Volume
Abstract: In recent years, Italy has been hit by earthquakes, causing significant damage to masonry and reinforced concrete (RC) structures. Especially, common buildings and ordinary structures in many small historical towns of Italian central regions, such as Marche, have suffered dramatic consequences and destruction. Dynamic analysis and seismic structural safety are important topics in civil engineering, which have been studied and deepened for many years by the researchers of the Structural Division of the Department of Civil and Building Engineering, and Architecture of UnivPM. The researches have been oriented towards the investigation of structures under seismic loads in order to improve the knowledge of the structural response under high actions, due to the soil dynamic movements and, thus, define adequate techniques to strengthen the damaged structures. In this paper we present a wide spectrum of main results of our research group, comprising experimental studies, vulnerability analysis and assessment of existing structures, new methods of modelling and theoretical approaches to define the dynamic behavior of structures, also in presence of damage. Finally, we show and discuss new prospects of research for safety, employing advanced techniques and materials to prevent collapse and/or relevant damages in structures.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/281739 Collegamento a IRIS

2019
Nonlinear Dynamics of a Planar Hinged-Simply Supported Beam with One End Spring: Higher Order Resonances
IUTAM Symposium on Exploiting Nonlinear Dynamics for Engineering Systems
Autore/i: Kloda, Lukasz; Lenci, Stefano; Warminski, Jerzy
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269316 Collegamento a IRIS

2019
The non-smooth story of different masonry towers damaged by the central Italy seismic sequence of 2016
COMPDYN 2019 Proceedings
Autore/i: Clementi, F.; Ferrante, A.; Giordano, E.; Lenci, S.
Editore: National Technical University of Athens
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The Non-Smooth Contact Dynamics method (NSCD) has been applied to the study of the seismic response of different belfries inside the epicentral zone of the last Centre Italy earthquakes of August and October 2016. According to this model, the masonry towers have been modelled as a system of rigid blocks, and since the contacts between blocks are governed by the Signorini's impenetrability condition and by dry-friction Coulomb's law, the towers exhibit discontinuous dynamics. The NSCD method has proved to be a powerful tool for investigating the dynamics induced by ground seismic accelerations. Indeed, the numerical results have given a deep insight into the seismic vulnerability of these damaged towers, confirming several possible failure mechanisms.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/274951 Collegamento a IRIS

2019
On a Geometrically Exact Beam Model and Its Finite Element Approximation
IUTAM Symposium on Exploiting Nonlinear Dynamics for Engineering Systems
Autore/i: Babilio, Enrico; Lenci, Stefano
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269317 Collegamento a IRIS

2019
Influence of FE Modelling Approaches on Vulnerabilities of RC School Buildings and Proposal of a CFRP Retrofitting Intervention
THE OPEN CONSTRUCTION & BUILDING TECHNOLOGY JOURNAL
Autore/i: Gazzani, V.; Poiani, M.; Clementi, F.; Pace, G.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: Background: The vulnerability assessment of existing school buildings against earthquakes represents a priority concern for society. In recent years, several countries promote seismic rehabilitation projects of school buildings, including the allocation of funds to regions with high seismic hazard. Objectives: This research aims to highlight some key role aspects related to difficulties encountered in the numerical modelling of RC structures hosting school activities. This work evaluates the seismic vulnerability of school buildings located in the municipality of Trecastelli (Marche, Central Italy) to quantify the effective influence of typical and specific seismic vulnerabilities detected on the global seismic behaviour of each building. The effectiveness of a possible Carbon Fibre Reinforced Polymer (CFRP) local strengthening intervention, for the case study, aimed to confine unconfined beam-column joints is also considered. Methods: Three different numerical models of a Reinforced Concrete (RC) school building are implemented with the lumped plasticity, the distributed plasticity (fibre) and the 3D Continuum Finite Element (FE) approaches. Nonlinear static (pushover) analyses are performed to assess the global seismic behaviour of the structure, and the limitations to represent the reality with different approaches. After the seismic vulnerability assessment of the case study, a CFRP retrofitting intervention is proposed to confine external beam-column joints. Results: The comparison of the numerical results of three models shows that the fibre model is the least suitable means to represent shear problems, while the lumped plasticity model is closer to reality than the previous one even if it does not take into account the concomitance of bending, shear and axial force and the interaction between them in the inelastic response. Of course, the 3D Continuum model is the most accurate representation to describe the complex and combined mechanisms developed in the joint panels. Nonlinear static (pushover) analyses carried out on unreinforced and reinforced structures of Continuum model demonstrate that the Fibre Reinforced Polymer (FRP) strengthening improves the displacement capacity of the structure. Conclusion: This study has highlighted the strengths and weaknesses of different modelling types. The meaningful information about mechanisms developed in joints given by the 3D Continuum FE model is useful to identify shortcomings of the design project and to conceive a retrofitting strengthening intervention. CFRP sheets externally bonded on beam-column joints may improve the seismic frame performances without a significant change of the structural stiffness, promoting a ductile failure mode with a higher displacement capacity than the unreinforced case.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/272403 Collegamento a IRIS

2019
Introduction to Scientific Computing Technologies for Global Analysis of Multidimensional Nonlinear Dynamical Systems
Nonlinear Structural Dynamics and Damping
Autore/i: Andonovski, Nemanja; Moglie, Franco; Lenci, Stefano
Editore: Springer International Publishing
Classificazione: 2 Contributo in Volume
Abstract: To determine global behaviour of a dynamical system, one must find invariant sets (attractors) and their respective basins of attraction. Since this cannot be made extensively with analytical methods, the numerical global analysis is currently the subject of intensive research, especially for strongly nonlinear, multidimensional dynamical systems. Numerical analysis in dimensions higher than four present a challenge, since it requires significant computing resources. Numerical methods used in global analysis that can benefit from high-power computing are those that can parallelize either data or task elaboration on a large scale. Mass parallelization comes with large number of difficulties, restrictions and programming hazards. When not implemented in compliance with hardware organization, data and instruction management can lead to severe loss of parallel algorithm performance. Systematic and methodical approach to design parallel programs is, therefore, critical to get the most from expensive high-power computing systems and to avoid unrealistic speed-up expectation. Considering these difficulties, the goal of this chapter is to introduce readers to the world of high-power computing systems for science and global analysis of strongly nonlinear, multidimensional dynamical systems. Topic covered are classification and performance of hardware and software, classes of computing problems and methodical design of programs. Two major hardware platforms used for scientific computing, clusters and systems with computational GPU are considered. Functionality of widely utilized software solutions (OpenMP, MPI, CUDA and OpenCL) for high-power computing systems is described. Performance of individual computer components are addressed so that the reader can understand advantages, disadvantages, efficiency and limits of each hardware platform. With this knowledge users can judge if their computation problem is suitable for mass parallelization. If this is the case, which hardware and software platforms to use. To avoid many traps of parallel programming, one of the methodical design approaches is covered. Topic is closed with example applications in science and global analysis.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/264456 Collegamento a IRIS

2019
Flood impact on masonry buildings: The effect of flow characteristics and incidence angle
JOURNAL OF FLUIDS AND STRUCTURES
Autore/i: Postacchini, Matteo; Zitti, Gianluca; Giordano, Ersilia; Clementi, Francesco; Darvini, Giovanna; Lenci, Stefano
Classificazione: 1 Contributo su Rivista
Abstract: Climate change and the raising number of extreme events, such as severe floods, has increased the attention on their effects on urban systems. Urban floods generate important hydrodynamic loads on building and this work proposes a first systematic study on the actions generated by floods with different characteristics (depth, velocity and incidence angle) on masonry buildings. The study is carried out with experimental tests reproducing a masonry bay with scale 1:10, while the effect of the flow hitting the building has been obtained by moving the building in the water at rest. The pressure generated by the fluid at the four walls of the building was recorded using pressure transducers. It has been found that the overpressure acting on the building depends on the flow characteristics in different manner for the frontal, lateral and rear walls. Further, the incidence angle plays a major role in the generation of a pressure gradient along the impacted wall, and significantly affects both peak frequency and spectral energy. Use of theoretical models suggests that (i) the drag coefficient of the building decreases with the Froude number, and only slightly depends on the incidence angle, and (ii) the blocking effect largely affects the hydrodynamics around the structure.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/266247 Collegamento a IRIS

2019
The Lossetti Tower in Beura-Cardezza (Italy): Structural Assessment and Rehabilitation of a Historical Dry Stone Masonry Building
RILEM Bookseries
Autore/i: Monni, F.; Quagliarini, E.; Lenci, S.
Editore: Springer Netherlands
Classificazione: 2 Contributo in Volume
Abstract: Dry stone masonry (DSM) is an ancient construction method widely used for vernacular and military buildings in rural and mountain regions. The use of this particular method is due to the large availability of natural stone that characterized these areas. The consolidation of DSM buildings is a challenging issue: in fact, this kind of masonry proved to be scarcely reliable under eccentric and horizontal loads and in absence of elements that are long enough to cross the masonry in its thickness. However, there are very few techniques that can preserve the peculiarities of a masonry texture. This paper presents the design approach that was used for the structural rehabilitation of the Lossetti Tower, a medieval DSM watchtower located in Beura-Cardezza (Italy, Piemonte Region). First, a preliminary research on the building was conducted. Secondly, to better understand the masonry quality, both a 3D laser scanning geometric survey and a technological study of the masonry typology and texture of the tower were executed. Thirdly, to evaluate the mechanical behaviour, a diagonal compression test on the DSM specimens was performed. Finally, after a structural assessment, was developed a tailored design of the strengthening intervention by using the technique of continuous basalt fibers stitching. The proposed system consists in creating a mesh of basalt fiber ropes, that passes through the masonry thickness and ties the blocks together. This system also allows to connect the wall in the transverse direction and to improve the monolithic behaviour of masonry panels in perfect compatibility with the original materials and it was preferred to the more invasive ones also for its reversibility
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/268475 Collegamento a IRIS

2018
FLOOD IMPACTS ON BUILDINGS: FIRST EXPERIMENTAL AND NUMERICAL RESULTS
Proceedings del XXXVI Convegno Nazionale di Idraulica e Costruzioni Idrauliche
Autore/i: Brocchini, Maurizio; Capozucca, Roberto; Clementi, Francesco; Darvini, Giovanna; Giordano, Ersilia; Lenci, Stefano; Postacchini, Matteo; Zitti, Gianluca
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263397 Collegamento a IRIS

2018
Numerical model upgrading of ancient bell towers monitored with a wired sensors network
Proceedings of the International Masonry Society Conferences
Autore/i: Clementi, F.; Pierdicca, A.; Milani, G.; Gazzani, V.; Poiani, M.; Lenci, S.
Editore: International Masonry Society
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: In this work, the opportunities provided by dynamic identification techniques for non-destructive evaluation of heritage structures are discussed with a focus on different bell towers, located in the Ferrara Province (Italy). All of them were stricken by a long seismic sequence (Emilia Romagna, North-East of Italy, May-June 2012 seismic sequence) and they are investigated in detail to have an insight into their dynamic behaviour. Furthermore, the experimental investigations and the operational modal analysis results are presented and they are useful for defining the Finite Element (FE) models of the towers within a continuum approach. The monitoring system consists of several sensors properly connected. The positioning of the instrumentation has been conditioned by many operative problems due to the limited accessibility of the structures, both related to the main access and to reaching the top. However, it has been possible to identify with a certain confidence the first three frequencies of the towers and their corresponding mode shapes. The results carried out after the FE updating procedure may be considered very good. The material data values estimated in this way will constitute an important reference for the evaluation of the state of the building.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/264150 Collegamento a IRIS

2018
DYNAMICS AND STABILITY: A LONG HISTORY FROM EQUILIBRIUM TO DYNAMICAL INTEGRITY
MEMORIE DELL'ISTITUTO LOMBARDO. ACCADEMIA DI SCIENZE E LETTERE. CLASSE DI SCIENZE MATEMATICHE E NATURALI
Autore/i: Maracci, Diletta; Lenci, Stefano
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/276839 Collegamento a IRIS

2018
Carbon nanofibers in polyurethane foams: Experimental evaluation of thermo-hygrometric and mechanical performance
POLYMER TESTING
Autore/i: Stazi, Francesca; Tittarelli, Francesca; Saltarelli, Federico; Chiappini, Gianluca; Morini, Antonio; Cerri, Graziano; Lenci, Stefano
Classificazione: 1 Contributo su Rivista
Abstract: Polymer nanocomposites synergistically combine the good thermal properties of the hosting polymer matrix with the high mechanical performance of the fillers, providing a new class of materials with superior properties. The present study aims to evaluate in a multidisciplinary way the enhancement in mechanical and thermalhygrometric properties of low and medium density nanophased polyurethane (PUR) foams with either randomly oriented or aligned nanofibers as compared to the neat ones. To this aim, 1% weight of carbon nanofibers (CNFs) were homogeneously dispersed into polyol of PUR foam by an ultrasonic cavitation method. In parallel, a small amount of CNFs was functionalized in advance by a coprecipitation method so as to align them into the polymer matrix through an external low intensity magnetic field. SEM analyses were used to compare the microstructure of the neat and nanophased samples. Results have shown that the addition of carbon nanofibers in the foams products a closer structure with a more uniform size and shape. Moreover, functionalized CNFs play a significant role in regulating cells shape as well as strengthening cells walls. Mechanical test results also demonstrated that CNFs increase both strength and stiffness of the samples. The alignment of carbon nanofibers within medium density nanophased foams determines the highest mechanical properties. However, the more noticeable improvement in samples performance occurred in low density nanophased foams. Finally, carbon nanoparticles decrease the thermal conductivity and increase the resistance against water adsorption.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/256087 Collegamento a IRIS

2018
Monitoring cultural heritage buildings: The San Ciriaco bell-tower in Ancona
Proceedings of the International Conference of Computational Methods in Sciences and Engineering 2018 (ICCMSE-2018)
Autore/i: Ribilotta, Elisa; Clementi, Francesco; Pellegrino, Marco; Poiani, Marina; Gazzani, Valentina; Santilli, Graziano; Lenci, Stefano
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The preliminary results of an ambient-vibration based investigation conducted on the San Ciriaco Belfry in Ancona (Italy) is presented. The assessment procedure includes full-scale ambient vibration testing, modal identification from ambient vibration responses, finite element modeling and dynamic-based identification of the uncertain structural parameters of the model. As the most doubtful parameters, the modulus of elasticity of the masonry is adjusted to achieve the experimental results with numerical model by simple operations
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/262450 Collegamento a IRIS

2018
Nonlinear dynamics of a planar beam–spring system: analytical and numerical approaches
NONLINEAR DYNAMICS
Autore/i: Kloda, Lukasz; Lenci, Stefano; Warminski, Jerzy
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/262699 Collegamento a IRIS

2018
Seamless variation of isometric and anisometric dynamical integrity measures in basins's erosion
COMMUNICATIONS IN NONLINEAR SCIENCE & NUMERICAL SIMULATION
Autore/i: Belardinelli, P.; Lenci, S.; Rega, G.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/254150 Collegamento a IRIS

2018
An innovative building envelope (kinetic façade) with Shape Memory Alloys used as actuators and sensors
AUTOMATION IN CONSTRUCTION
Autore/i: FORMENTINI, MARCO; Lenci, Stefano
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/254151 Collegamento a IRIS

2018
Axial-transversal coupling in the nonlinear dynamics of a beam with an inclined roller
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
Autore/i: Lenci, S.; Clementi, F.
Classificazione: 1 Contributo su Rivista
Abstract: The nonlinear oscillations of an Euler–Bernoulli beam hinged at one end and having a roller support sliding on a inclined line on the other end are investigated for the first time (to the best of the authors’ knowledge). Free and forced dynamics are studied, and the backbone curve and frequency response curve are obtained by the multiple time scale method. These results allow us to detect analytically the main features of the nonlinear dynamics, in particular the hardening/softening dichotomy, and how it is influenced by the various beam parameters. Furthermore, the analytical results are compared with finite element simulations to check their reliability. The main goal of the paper is that of investigating the coupling between axial and transversal displacements, which appears yet in the linear regime (first order solution) due to the slope of the constraint. An element of novelty consists of showing the qualitative and quantitative changes that the coupling undergoes passing from small (linear regime) to moderate and large (nonlinear regime) displacements.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/258881 Collegamento a IRIS

2018
Seismic Assessment of a Monumental Building through Nonlinear Analyses of a 3D Solid Model
JOURNAL OF EARTHQUAKE ENGINEERING
Autore/i: Clementi, F.; Gazzani, V.; Poiani, M.; Mezzapelle, P. A.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: The paper analyzes the static behavior and the seismic vulnerability of the “San Francesco ad Alto” building in Ancona (Italy), which is currently used as a Regional Headquarter of the Marche Region by the Italian Army and was formerly a monastery. The global static structural behavior and the dynamic properties have been evaluated using the Finite Element modeling technique, in which the nonlinear behavior of masonry has been taken into account by proper constitutive laws. The concepts of homogenized material and smeared cracking are used to evaluate the capacity of the monastery to withstand lateral loads together with the expected demands resulting from seismic actions (N2 method), using a nonlinear static analysis (pushover). The comparison of seismic demand and capacity confirms the susceptibility of these types of buildings to extensive damage and collapse, as frequently observed in similar buildings. This paper aims to point out that advanced numerical analyses can offer significant information on the understanding of the actual structural behavior of historical buildings. It is believed that the methodology and the overall conclusions of this case study are valid for many historical monasteries in Europe.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247516 Collegamento a IRIS

2018
Modal parameters identification with environmental tests and advanced numerical analyses for masonry bell towers: a meaningful case study
Proceedings of XIV International Conference on Building Pathology and Constructions Repair – CINPAR 2018
Autore/i: Gazzani, V.; Poiani, M.; Clementi, F.; Milani, G.; Lenci, S.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: In the first part, a dynamic monitoring for non-destructive evaluation of heritage structures is discussed with reference to a case study, namely the Pomposa Abbey belfry, located in the Ferrara Province (Italy). The main dynamic parameters constitute an important reference to define an advanced numerical model, discussed in the second part, based on Non-Smooth Contact Dynamics (NSCD) method. Schematised as a system of rigid blocks undergoing frictional sliding and plastic impacts, the tower has exhibited complex dynamics, because of both geometrical nonlinearity and the non-smooth nature of the contact laws. First, harmonic oscillations have been applied to the basement of the tower and a systematic parametric study has been conducted, aimed at correlating the system vulnerability to the values of amplitude and frequency of the assigned excitation corroborated by the dynamic identification results. In addition, numerical analyses have been done to highlight the effects of the friction coefficient and of the blocks geometries on the dynamics, in particular on the collapse modes. Finally, a study of the tower stability against seismic excitations has been addressed and 3D simulations have been performed with a real earthquake.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/262326 Collegamento a IRIS

2018
Foldover effect and energy output from a nonlinear pseudo-maglev harvester
AIP Conference Proceedings
Autore/i: Kecik, Krzysztof; Mitura, Andrzej; Warminski, Jerzy; Lenci, Stefano
Editore: American Institute of Physics Inc.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259996 Collegamento a IRIS

2018
Iconic crumbling of the clock tower in Amatrice after 2016 central Italy seismic sequence: advanced numerical insight
Proceedings of XIV International Conference on Building Pathology and Constructions Repair – CINPAR 2018
Autore/i: Poiani, M.; Gazzani, V.; Clementi, F.; Milani, G.; Valente, M.; Lenci, S.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The present paper investigates from an advanced numerical point of view the progressive damage of the Amatrice (Rieti, Italy) civic clock tower, after a long sequence of strong earthquakes that struck central Italy in 2016. Two advanced numerical models are here utilised to have an insight into the modalities of progressive damage and the behaviour of the structure under strong non-linear dynamic excitations, namely a Non-Smooth Contact Dynamics (NSCD) and a FE Concrete Damage Plasticity (CDP) models. In both cases, a full 3D detailed discretization is adopted. From the numerical results, both the role played by the actual geometries and the insufficient resistance of the constituent materials are envisaged, showing a good match with actual crack patterns observed after the seismic sequence.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/262325 Collegamento a IRIS

2018
Externally excited purely nonlinear oscillators: insights into their response at different excitation frequencies
NONLINEAR DYNAMICS
Autore/i: Kovacic, Ivana; Lenci, Stefano
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/254149 Collegamento a IRIS

2018
Nonlinear dynamics of a planar hinged-supported beam with one end spring system
MATEC Web of Conferences
Autore/i: Kloda, Lukasz; Lenci, Stefano; Warminski, Jerzy
Editore: EDP Sciences
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259998 Collegamento a IRIS

2018
Stochastic Switching and Reduction of Integrity in Atomic Force Microscopy
ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference
Autore/i: Belardinelli, Pierpaolo; Lenci, Stefano; Alijani, Farbod
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/269428 Collegamento a IRIS

2018
Isochronous beams by an inclined roller support
JOURNAL OF APPLIED MECHANICS
Autore/i: Lenci, Stefano
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/260000 Collegamento a IRIS

2018
The non-smooth contact dynamics method for the analysis of an ancient masonry tower
Proceedings of INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2018 (ICCMSE 2018)
Autore/i: Clementi, Francesco; Milani, Gabriele; Gazzani, Valentina; Poiani, Marina; Cocchi, Giammichele; Lenci, Stefano
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The dynamics of a medieval tower, inside the Basilica of San Benedetto in Ferrara (Italy), subjected to transversal dynamic loadings has been analyzed by using a distinct element code which implements the Non-Smooth Contact dynamics method. Since the contact between blocks is governed by the Signorini’s impenetrability condition and the dry-friction Coulomb’s law, the tower exhibits discontinuous dynamics. The sliding motions of blocks are non-smooth functions of time. Numerical simulations are performed with the aim of investigating the influence of the friction coefficient but also of the amplitude and frequency of the excitation at the base.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/262449 Collegamento a IRIS

2018
Revealing compactness of basins of attraction of multi-DoF dynamical systems
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
Autore/i: Brzeski, P.; Belardinelli, P.; Lenci, S.; Perlikowski, P.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259290 Collegamento a IRIS

2017
FREQUENZE PROPRIE E COMPORTAMENTO ACUSTICO DI VETRATE DI SICUREZZA IN APPLICAZIONI EDILI
STRUCTURAL
Autore/i: Consolini, L.; Clementi, F.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: Con l’introduzione in campo nazionale della Norma UNI 7697:2015 – Criteri di sicurezza per le applicazioni vetrarie, si è data ancora più importanza alla scelta delle vetrate stratificate di sicurezza da utilizzarsi nelle diverse e più comuni applicazioni. Il vetro, ed in particolare il vetro stratificato di sicurezza, è infatti diventato sempre più utilizzato in edilizia e architettura. Quindi esso è stato sempre più oggetto di studio per comprenderne il comportamento meccanico. In questo lavoro, i moduli elastici sono determinati tramite identificazione dinamica “Modal Testing”, cioè l’acquisizione di dati sperimentali e il loro successivo post-processing per l’identificazione di un modello matematico che descriva il comportamento dinamico della struttura. Le frequenze e gli smorzamenti modali sono stati identificati mediante il metodo “Fitting Time History” (FTH), basato sull’acquisizione di accelerogrammi ed un’ottimizzazione ai minimi quadrati tra il segnale misurato ed un’approssimazione analiticamente determinata. Si affronta anche il tema dell’isolamento acustico dei medesimi componenti vetrati, essendo la risposta vibrazionale strettamente connessa al comportamento acustico del vetro.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251137 Collegamento a IRIS

2017
Basalt fiber continuous stitchings for strengthening the dry stone masonry of the Lossetti Tower in Beura-Cardezza (Italy)
TEMA
Autore/i: Monni, F.; Quagliarini, E.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: Dry stone masonry is widely used in rural and mountain regions and its consolidation is a challenge issue if it is wanted to preserve the peculiarities of masonry texture. In this paper is presented the design approach used for consolidation intervention of Lossetti Tower - a medieval dry stone watchtower located in Beura-Cardezza (Italy, Piemonte Region) - using the technique of continuous basalt fibres stitching, consisting in creating a mesh of BF ropes, which pass through the masonry thickness and tie blocks together. A 3D laser scanner survey of the tower was executed and, to evaluate the technique effectiveness, diagonal compression test on masonry specimens was done, in order to develop a tailored design of the strengthening intervention, in perfect compatibility with the original structures
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/255483 Collegamento a IRIS

2017
Riduzione del rischio sismico e retrofitting degli edifici scolastici: il caso della scuola “Puccini” di Senigallia (AN)
Colloqui.AT.e 2017. DEMOLITION OR RECONSTRUCTION?
Autore/i: Monni, F.; Quagliarini, E.; Lenci, S.; Clementi, Francesco
Editore: Edicom edizioni, Monfalcone (Gorizia)
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/255484 Collegamento a IRIS

2017
Edifici esistenti in muratura e terremoto: tecnologie innovative e conoscenza per aumentare la resilienza
Building Back Better: idee e percorsi per la costruzione di comunità resilienti
Autore/i: Lenci, Stefano; Mezzapelle, PARDO ANTONIO; Clementi, Francesco
Editore: Carocci editore pressonline
Luogo di pubblicazione: Roma
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/252044 Collegamento a IRIS

2017
Experimental investigation of masonry columns strengthening using basalt fibre ropes: first results
REHAB 2017
Autore/i: Monni, F.; Quagliarini, E.; Vaccarini, M.; Lenci, S.
Editore: Green Lines Institute for Sustainable Development
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/255486 Collegamento a IRIS

2017
The NSCD method for dynamic analyses of ancient masonry tower under transversal dynamic loadings
Proceedings of 9th European Nonlinear Dynamics Conference
Autore/i: Clementi, F.; Ferrante, A.; Lenci, S.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/249549 Collegamento a IRIS

2017
The Use of the Fitting Time Histories Method to Detect the Nonlinear Behaviour of Laminated Glass
JOURNAL OF VIBRATION TESTING AND SYSTEM DYNAMICS
Autore/i: Lenci, S.; Consolini, L.; Clementi, F.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/246854 Collegamento a IRIS

2017
TECNICHE DI IDENTIFICAZIONE MODALE PER L’ANALISI STRUTTURALE. L’evoluzione del comportamento dinamico di un edificio scolastico in cemento armato soggetto a miglioramento sismico
STRUCTURAL
Autore/i: Clementi, F.; Lenci, S.; Monni, F.; Pierdicca, A.; Massaccesi, M.
Classificazione: 1 Contributo su Rivista
Abstract: This work deals with the structural retrofitting of a Reinforced Concrete (RC) building school and illustrates the results of a structural monitoring campaign performed on this. The examined school building presents typical and specific vulnerabilities of Italian building stock - of which RC buildings currently represent the greatest portion - mostly built in 60’s and 70’s Because of its vulnerabilities, the structure was subjected to a deep structural retrofitting intervention based on increasing of original columns cross-sections with introduction of new longitudinal steel bars and stirrups, and application of shear reinforcement on beams using Fiber Reinforced Polymers (FRP). The building was monitored using Operational Modal Analysis (OMA) technique, that offers the possibility of describing structural dynamics at small vibration amplitudes in real operating conditions with unknown excitation inputs. The long-term Ambient Vibration Survey (AVS) - performed before, during and after the works, in a campaign lasted one year - highlighted the increasing of building performance in terms of natural frequencies following the retrofitting works. Moreover, the paper shows how infill panels influence the dynamic response of this typical RC structure. This relevant data collection, in addition to confirm the potentil of OMA technique in gathering the real structure behavoiur, could be very helpful in the calibration of other similar retrofitting interventions.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/248956 Collegamento a IRIS

2017
Analisi delle vulnerabilità sismiche locali
San Francesco ad Alto di Ancona - Storia, analisi e ipotesi di valorizzazione architettonica
Autore/i: Lenci, Stefano; Clementi, Francesco; Mezzapelle, PARDO ANTONIO
Editore: Aracne editrice
Luogo di pubblicazione: Canterano (RM)
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/252045 Collegamento a IRIS

2017
Cultural Heritage and Earthquake: The Case Study of “Santa Maria Della Carità” in Ascoli Piceno
THE OPEN CIVIL ENGINEERING JOURNAL
Autore/i: Clementi, F.; Quagliarini, E.; Monni, F.; Giordano, E.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/252430 Collegamento a IRIS

2017
On the notion of curvature and its mechanical meaning in a geometrically exact plane beam theory
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
Autore/i: Babilio, Enrico; Lenci, Stefano
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/254140 Collegamento a IRIS

2017
Comparing Nonlinear Free Vibrations of Timoshenko Beams with Mechanical or Geometric Curvature Definition
Proceedings of the International Congresses on Theoretical and Applied Mechanics (ICTAM)
Autore/i: Lenci, S.; Clementi, F.; Rega, G.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/246049 Collegamento a IRIS

2017
Energy harvesting from a magnetic levitation system
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
Autore/i: Kecik, Krzysztof; Mitura, Andrzej; LENCI, Stefano; Warminski, Jerzy
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/246857 Collegamento a IRIS

2017
Numerical model upgrading of a historical masonry building damaged during the 2016 Italian earthquakes: the case study of the Podestà palace in Montelupone (Italy)
JOURNAL OF CIVIL STRUCTURAL HEALTH MONITORING
Autore/i: Clementi, F.; Pierdicca, A.; Formisano, A.; Catinari, F.; Lenci, S.
Classificazione: 1 Contributo su Rivista
Abstract: In October 2016, two major earthquakes occurred in Marche region in the Centre of Italy, causing widespread damage. The epicentre of the second one struck Norcia, Visso and Accumoli and a lot of damages to cultural heritage were done in the cities of Tolentino, San Severino, Camerino, Matelica, Macerata and Montelupone, where are located the Podestà Palace and the Civic Tower investigated in this paper. The main aim of this research is the determination of modal properties of these historical masonry constructions using experimental and numerical studies. The experimental analysis was based on ambient vibration survey, while numerical analysis was based on finite element analysis with solid elements. The results of the experimental study were used to tune the numerical model of the structure. As the most doubtful parameters, the modulus of elasticity of the masonry and the interaction among structural parts were adjusted to achieve the experimental results with numerical model by simple operations. Obtaining good consistency between the experimental and numerical analyses, the study revealed the actual dynamic properties of the damaged palace.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251396 Collegamento a IRIS




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