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Ingeniero Industrial Antolín Lorenzana-Ibán*** Dr. ... Control de Vibraciones en Pasarelas Peatonales Carlos Mariano Casado-Sánchez, Jesús de Sebastián-Sanz, Iván Muñoz-Díaz, Alfonso Poncela-Méndez, Antolín Lorenzana-Ibán Informe Técnico 326 PRUEBAS DE ...doi:10.6036/4051 fatcat:ileoo2uihzcr5bslh7t4tdd4ba
The present paper studies the performance of a tuned mass damper (TMD) installed in a 183 m tall chimney located at the edge of the wake shed by another chimney. Numerical and experimental results are available. For the simulations, wind action is considered by solving several 2D flow problems on a selected number of horizontal planes, in the transverse direction to the stacks. On such planes, Navier-Stokes equations are solved to estimate the fluid action at different positions of the chimneysdoi:10.3390/act10010012 fatcat:r6vul3a3tbbs7i64fpjau2mg5a
more »... and standard interpolation techniques are applied in the vertical direction. An Arbitrary Lagrangian-Eulerian (ALE) approach is used to consider the moving domain, and a fractional-step scheme is used to solve the fluid field. For the structural modelling, chimneys are meshed using 3D beam finite elements. The time integration procedure used for the structural dynamics is based on the standard second order Bossak method. For each period of time, the fluid problem is solved, the aeroelastic analysis is carried out and the geometry of the fluid mesh of each plane is updated according to the structural movements. With this procedure and model updating techniques, the response of the leeward chimney is evaluated for different scenarios, revealing an interesting dependence of the TMD performance on the wind speed and direction.
The analysis of the interaction between a fluid flow and any object represents a classical challenge for modern numerical techniques. A one-dimensional model is presented for the analysis of thin-walled composite beams under the action of a fluid flow. Beam walls are made of orthotropic layers bonded together to form a laminate that might be anisotropic. The Navier-Bernoulli and Vlasov models are used to describe bending and torsion at a beam level. The constitutive equations are modeled at thedoi:10.1515/secm.2010.17.1.47 fatcat:zvc5lcamsfhchnwxnho47ywq5u
more »... lamina level using the Love-Kirchhoff model. A 5 5 cross-sectional stiffness matrix that relates one-dimensional generalized beam forces and moments to one-dimensional generalized displacements is obtained. It is used for the definition of a beam element which is suitable for the simulation of both open-section and closed-section beams of an arbitrary section shape with arbitrary layup. The typical laminations for a box-beam, Circumferentially Uniform Stiffness (CUS) and Circumferentially Asymmetric Stiffness (CAS), are analyzed. The aeroelastic analysis of a slender beam is performed coupling a Navier Stokes solver with the structural model. The results are analyzed and the effects of the layup are shown.
Tuned Mass Dampers are devices which can be assimilated to single-degree-of-freedom systems with a certain amount of moving mass, a natural frequency and a damping ratio intended to be installed on lively structures to reduce the contribution of a certain mode to their response. Once placed on the structure, the movement of the mass damper couples to the structural response and determines its properties as an isolated system becomes challenging. The authors have previously presented adoi:10.3390/app11104712 fatcat:pxe4eltwqzg3zkx5eoov7pk65u
more »... y to estimate the natural frequency and damping ratio of an SDOF system installed on a structure and not necessarily tuned to a certain mode. It was based on a transmissibility function and, thus, the moving mass could not be estimated. With this work, the authors go one step further and present a novel procedure to estimate the moving mass value by means of the same transmissibility function and two well selected frequency response functions. The methodology is applied to estimate the properties of a real single-degree-of-freedom system placed on a lively timber platform. The results are compared with the mass modification technique to show that the proposed methodology provides better estimations in a more efficient way.
Topics in Modal Analysis I, Volume 5
Effects of structural flexibility on the dynamic performance of structures such as staircases, footbridges, and long span floors is becoming an increasingly important aspect of modern design. Cost reduction, improving efficiency of design, enhancement of aesthetic perception and, innovation in architectural forms often result in slender and lightweight structures that are significantly more flexible and vibrationprone than ever before. Consequently, meeting relevant vibration serviceabilitydoi:10.1007/978-1-4614-2425-3_51 fatcat:v6sn4ag3drdrxjhgdfz6c723ha
more »... eria, as opposed to ultimate strength requirements, is becoming the governing factor in the design of many new structures. Despite significant advances in numerical prediction of modal properties of structures using Finite Element (FE) modelling technique, there still exist challenges in accurate representation of the actual dynamic behaviour. This is mainly due to some inherent modelling uncertainties related to a lack of information on the as-built structures, such as uncertainties in boundary conditions, material properties and the effects of non-structural elements. This paper presents the results of a modal testing exercise carried out to assess the dynamic behaviour of a lively staircase structure. The assessment procedure includes a full-scale ambient vibration testing, modal identification and FE modelling and updating. In particular, the influence of boundary conditions and presence of handrails on dynamic properties of the structure are commented.
One of the most popular options in the Structural Health Monitoring field is the tracking of the modal parameters, which are estimated through the frequency response functions of the structure, usually in the form of accelerances, which are computed as the ratio between the measured accelerations and the applied forces. This requires the use of devices capable of synchronously recording accelerations at several points of the structure at high sampling rates and the subsequent computationaldoi:10.3390/s21196637 pmid:34640957 pmcid:PMC8512721 fatcat:cbnmdkudwvhkrnzs2bs2j4d3x4
more »... sis using the recorded data. To this end, this work presents and validates a new scalable acquisition system based on multiple myRIO devices and digital MEMS (Micro-Electro-Mechanical System) accelerometers, intended for modal analysis of large structures. A simple form of this system was presented by the authors in a previous work, showing that a single board with some accelerometers connected to it got to obtain high quality measurements in both time and frequency domains. Now, a larger system composed by several slave boards connected and synchronized to a master one is presented. Delays lower than 100 ns are found between the synchronised channels of the proposed system. For validation purposes, a case study is presented where the devices are deployed on a timber platform to estimate its modal properties, which are compared with the ones provided by a commercial system, based on analog accelerometers, to show that similar results are obtained at a significantly lower cost.
Lorenzana, PhysEx: A novel procedure to estimate full-rank physical matrices of a structure from an incomplete modal model, Journal of Sound and Vibration (2021), doi: https://doi. ...doi:10.1016/j.jsv.2021.116277 fatcat:6n55xlg7uzccrdrmrpz3yqnnbi
This paper presents the design, development and testing of a low-cost Structural Health Monitoring (SHM) system based on MEMS (Micro Electro-Mechanical Systems) triaxial accelerometers. A new control system composed by a myRIO platform, managed by specific LabVIEW software, has been developed. The LabVIEW software also computes the frequency response functions for the subsequent modal analysis. The proposed SHM system was validated by comparing the data measured by this set-up with adoi:10.3390/s21020648 pmid:33477780 fatcat:fnx4fcyb3baubpfb5jg2gor3dy
more »... l SHM system based on piezoelectric accelerometers. After carrying out some validation tests, a high correlation can be appreciated in the behavior of both systems, being possible to conclude that the proposed system is sufficiently accurate and sensitive for operative purposes, apart from being significantly more affordable than the traditional one.
The current trend toward lighter and slender pedestrian structures, with new aesthetic requirements and highperformance materials, has resulted in structures with increased susceptibility to vibration. Notable vibrations under human-induced excitations might appear, and the vibration serviceability requirements might not be accomplished. The Valladolid Science Museum Footbridge (Spain) is an example of a lively structure that might achieve excessive vertical acceleration under walking ordoi:10.1002/stc.471 fatcat:2c4ph5olozhyfev24euzrfqrti
more »... excitation. The control of excessive footbridge vibrations via passive and active devices is dealt with in this work. More specifically, this paper is concerned with the design and experimental implementation of a passive tuned mass damper (TMD) and an active mass damper (AMD) to mitigate human-induced vibrations on this in-service footbridge. The TMD, with a mass ratio of 1%, is designed by a numerical method based on H ∞ controllers. The AMD consists of a proof-mass actuator, with a mass ratio of approximately 0.2%, controlled by a strategy based on acceleration feedback with a phase-lag network. The performance of both devices has been assessed. structure to reduce the human influence, a proportional increase of stiffness being also necessary; and (iv) increasing the damping of the structure with special devices. Taking into account that stiffening the structure and increasing the mass are usually complicated and involve significant structural and non-structural changes, the alternative option of including damping devices to the structure seems to be the easiest way of improving the vibration performance of footbridges. Typical passive damping systems  are metallic dampers, friction dampers, visco-elastic dampers, viscous dampers, tuned mass dampers (TMDs) and tuned liquid dampers (TLDs). Among passive control devices available for implementation in footbridges, TMDs [7, 8] (including parallel multiple TMDs  and series multiple TMDs ), TLDs  and fluid-viscous dampers are the most effective and, hence, the usual adopted solution  . An alternative procedure to cancel footbridge vibrations is the use of active devices. Moutinho et al.  have recently implemented an active vibration control (AVC) on a stress-ribbon footbridge using a proof-mass actuator together with direct velocity feedback control (DVFC) with saturation. This actuator generates inertial forces in the structure without need for a fixed reference. The velocity output, which is obtained by an integrator circuit applied to the measured acceleration response, is multiplied by a gain and feeds back to a collocated actuator. The term collocated means that the actuator and sensor are located physically at the same point on the structure. The merits of this method are its robustness to spillover effects due to high-order unmodelled dynamics and that it is unconditionally stable in the absence of actuator and sensor (accelerometer with an integrator circuit) dynamics  . Nonetheless, when such dynamics are considered, the stability for high gains is no longer guaranteed, and the system can exhibit limit cycle behaviour, which is not desirable since it could result in dramatic effects on the system performance and its components  . Then, DVFC with saturation is not such a desirable solution. Generally, the actuator and sensor dynamics influence the system dynamics and have to be considered in the design process of the AVC system. If the interaction between sensor/actuator and structure dynamics is not taken into account, the AVC system might exhibit poor stability margins, be sensitive to parameter uncertainties and be ineffective. Díaz and Reynolds  have recently proposed a control strategy based on a phase-lag compensator applied to the structure acceleration, which is usually the actual magnitude measured. This compensator accounts for the interaction between the structure and the actuator and sensor dynamics in such a way that the closed-loop system shows desirable properties. Such properties are high damping for the fundamental vibration mode of the structure and high stability margins. Both properties lead to a closed-loop system robust with respect to stability and performance  . This control law is completed by the following: (i) a high-pass filter, applied to the output of the phase-lag compensator, designed to avoid actuator stroke saturation due to low-frequency components and (ii) a saturation nonlinearity applied to the control signal to avoid actuator force overloading at any frequency. This methodology will be referred as to compensated acceleration feedback control (CAFC) from this point onwards. This paper presents the practical implementation of inertial mass-based damping devices, passive and active, in order to cancel excessive vertical vibrations on a footbridge. More specifically, this paper addresses the design and implementation of a passive TMD and an active mass damper (AMD) on the Valladolid Science Museum Footbridge (Spain). This is a structure composed of four spans. One of them, which is a 51-m long steel structure, is considered by its users to be quite lively. The first bending mode of this span is at approximately 3.5 Hz in such a way that it might be excited by the second harmonic of walking and by the first harmonic of running. It was decided to install the designed damping devices at the point in which the first bending mode shape has its maximum value, which is close to the mid-span. The TMD, with an inertial mass ratio of approximately 1% of the modal mass of the targeted vibration mode, was designed by a numerical method based on H ∞ controllers  . The mass value of 1% of modal mass was found to be enough to keep the vibration level for a synchronised walker and runner within most of the limit values provided by current codes  . The H ∞ -based method used for the TMD design obtains the damping ratio and natural frequency of the TMD through the minimisation of the H ∞ -norm of the transfer function between the structure acceleration (output) and the force disturbance (input). H ∞ -based techniques are usually recommended for structures excited by loads exhibiting mainly periodical time components, such as those generated by human activities like walking or running. The AMD consisted of a commercial electrodynamic inertial actuator (with an inertial mass of around 0.15% of the modal mass) controlled via CAFC  . C. M. CASADO ET AL. S Sc ci ie en nc ce e M Mu us se eu um m S Sp pa an n 2 2 S Sp pa an n 3 3. . M Ma ai in n s sp pa an n P Po os st t--t te en ns si io on n c ca ab bl le es s T Th he e P Pi is su ue er rg ga a R Ri iv ve er r Figure 1. General view of the test structure.
Plan 455 Código 42622 Periodo de impartición 7º Cuatrimestre Tipo/Carácter Obligatorio Nivel/Ciclo Grado Curso 4 Créditos ECTS 6 Lengua en que se imparte Español Profesor/es responsable/s Horario de tutorías Horario disponible en a través del campus virtual. Lugar: laboratorio S10, EII. Cauce Recomendable cita previa mediante correo electrónico a firstname.lastname@example.org desde una cuenta de la Universidad de Valladolidfatcat:24byb6qyxrefzb4ui72tuzoxoa
Módulo común Titulación Master en Ingeniería Industrial Plan 511 Código 53292 Periodo de impartición 3º Cuatrimestre Tipo/Carácter Obligatorio Nivel/Ciclo Máster Curso 2 Créditos ECTS 5 Lengua en que se imparte castellano Profesor/es responsable/s Horario de tutorías Horario disponible en a través del campus virtual. Lugar: laboratorio S10, EII. Cauce Recomendable cita previa mediante correo electrónico es desde una cuenta de la Universidad de Valladolidfatcat:au6h7stxwnap3l2j26x4huukzu
EACS 2016 Paper No. 174 (113)This work proposes an implementation example of two tuned mass dampers (TDM) on a reduced scale two storey building. The TMD, in which the damping is magnetically adjusted without contact, is a laboratory prototype built in CARTIF (Spain). This TMD consists on a one degree of freedom system formed by a permanent magnet (mass) fixed to a flexible link (elasticity) and an aluminum plate at an adjustable distance to the magnet (damping). The tuning of the TMDs isdoi:10.15131/shef.data.4206450.v1 fatcat:4geznzzslzg6rm523f3zshhiye
more »... d out by considering the passive system as a feedback controller. The system identification and the experimental results show the validity of theoretical approximations and the design criterions.
EACS 2016 Paper No. 182Structures subjected to excitations like human induced vibrations may produce large accelerations and serviceability limit state problems. Passive, semi-active and active vibration controls have been proposed as possible solutions to reduce the vibration level at civil structures such as bridges, multi-storey buildings or slender floor structures, among others . It is known that Tuned Mass Dampers (TMD) mitigates the vibration response of a structure by increasing itsdoi:10.15131/shef.data.4206525.v1 fatcat:w66senr3izfkfhsavbf3bwztmm
more »... amping through the application of inertial forces generated in response to the movement of the structure . Recently, different TMD implementations have been proposed in order to improve the tuning of mechanical parameters. In the case of structures with spatially distributed and closely spaced natural frequencies, the TMD design may not be obvious because Den Hartog's theory  may not be applied due to the existence of a coupling between the motions of the vibration modes of the structures and the used TMD's . Alternative design techniques are applied for the case under study consisting on an arched bridge with a main span 40m long and several shorter access spans. The first two first modes are at 2.1Hz and 2.5Hz, both in the range prone to be excited by walking. Also the third one (at 3.18Hz) could be excited by runners.For the simulation, firstly, a finite element model of the bridge is created in a commercial CAE software and static and modal response is numerically estimated. Then, experimental measurements using static loading test and ambient vibration tests are performed. Initial finite element model is adjusted to match with the static response by fitting some selected parameters. Modal parameters (natural frequencies, mode shapes and modal damping) are extracted and after that the current finite element model is updated. Once the numerical model is calibrated, TMDs are attached. The problem of finding the optimal location and tuning is not a simple one. For understanding the coupled response, s [...]
Lorenzana (Rome, 1797), excerpts in H. Hagen, Anecdota Helvetica, cciv-ccxxxviii; De vitiis et figuris (ed. W. Lindsay, Oxford, 1922). % C, H. ... Antolin, ‘Estudios de codices visigodos,’ Bolet. Acad. Hist., trv (Madrid, 1909), 55. 1 Chronicon de Alfonso III, pp. 56 and 101, n. 73. 103 Conc. ...
Por su parte, los Rodríguez Lorenzana afirmaban estar emparentados “con el glorioso mártir San Vicente Lorenzana”, muerto en el siglo VI. ... Antolín oficial de la Secretaría de Estado, por lo que ambos alcanzarán como recompensa la orden de Carlos III, como ya la había logrado su progenitor y lo hará posteriormente uno de sus primos carnales ...doi:10.4000/nuevomundo.20502 fatcat:3pv525xnhrb5zigmcva7xy6bpm
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