Journal articles: 'Friction Pendulum Device'

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Sun, Yuhan, Yaodong Xue, Zhicheng Lu, and Po Gao. "Study on Mechanical Properties of Friction Pendulum Isolation Device for Transformer." Journal of Physics: Conference Series 2310, no. 1 (October 1, 2022): 012034. http://dx.doi.org/10.1088/1742-6596/2310/1/012034.

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Abstract Electrical equipment has high vulnerability under strong earthquakes due to its own material and structure characteristics. The seismic performance of electrical equipment can be effectively improved by installing isolation devices. Based on the finite element simulation, this paper establishes the finite element simulation model of the friction pendulum isolation device suitable for the main transformer electrical equipment, calculates and compares the mechanical response of the isolation device under different design parameters. The results show that the friction pendulum isolation device with conventional design can meet the load-bearing requirements of the main transformer under conventional conditions; increasing the friction coefficient can effectively improve the energy dissipation effect of the friction pendulum isolation device, but the increase of the friction coefficient will limit the design displacement of the isolation device, and the specific isolation effect needs to be further evaluated; changing the curvature radius of sliding surface has little effect on energy dissipation of friction pendulum isolation device. The research results in this paper can provide research basis for the application of friction pendulum isolation device in the field of electrical equipment.

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Alhasan, Ahmad, Omar Smadi, Georges Bou-Saab, Nacu Hernandez, and Eric Cochran. "Pavement Friction Modeling using Texture Measurements and Pendulum Skid Tester." Transportation Research Record: Journal of the Transportation Research Board 2672, no. 40 (May 30, 2018): 440–51. http://dx.doi.org/10.1177/0361198118774165.

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Pavement frictional behavior affects pavement performance in terms of vehicle safety, fuel consumption, and tire wear. Comprehending and interpreting pavement friction measurements is a challenging task, because of friction sensitivity to several uncontrollable factors. These factors include: pavement surface conditions, such as the type and thickness of contaminants and fluids on the surface and their interaction with friction forces; and the device operating conditions, such as sliding speed, material properties and geometry of the rubber slider used, and operating temperature. Despite the efforts to describe and quantify the impact of varying conditions on pavement friction, which ultimately will allow for a better harmonization of friction measurements, there is a need to better understand the link between the surface texture and physical friction measurements. In this paper, Persson’s friction model is used to analyze and understand the impact of surface texture on frictional behavior of dry pavement surfaces. The model was used to analyze 18 test locations, which were compared with the dry kinetic coefficients of friction (COF) estimated using a British pendulum tester (BPT). The results show that Persson’s friction model could predict the COF estimated from the BPT results with relatively high accuracy. In addition, the model could provide a profound explanation of the frictional forces mechanism. Finally, it was found that the mean profile depth (MPD) cannot provide a full picture of the frictional behavior. However, combining MPD with the Hurst exponent, texture measurements can potentially provide a full physical explanation of the frictional behavior for road surfaces.

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Bianco, Vincenzo, Giorgio Monti, and Nicola Pio Belfiore. "FINE-TUNING OF MODELLING STRATEGY TO SIMULATE THERMO-MECHANICAL BEHAVIOUR OF DOUBLE FRICTION PENDULUM SEISMIC ISOLATORS UST ESTIMATOR." NED University Journal of Research 3, Special Issue on First SACEE'19 (December 12, 2019): 165–72. http://dx.doi.org/10.35453/nedjr-stmech-2019-0058.

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The use of friction pendulum devices has recently attracted the attention of both academic and professional engineers for the protection of structures in seismic areas. Although the effectiveness of these has been shown by the experimental testing carried out worldwide, many aspects still need to be investigated for further improvement and optimisation. A thermo-mechanical model of a double friction pendulum device (based on the most recent modelling techniques adopted in multibody dynamics) is presented in this paper. The proposed model is based on the observation that sliding may not take place as ideally as is indicated in the literature. On the contrary, the fulfilment of geometrical compatibility between the constitutive bodies (during an earthquake) suggests a very peculiar dynamic behaviour composed of a continuous alternation of sticking and slipping phases. The thermo-mechanical model of a double friction pendulum device (based on the most recent modelling techniques adopted in multibody dynamics) is presented. The process of fine-tuning of the selected modelling strategy (available to date) is also described.

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Zhou, Fangyuan, Weilin Xiang, Kun Ye, and Hongping Zhu. "Theoretical study of the double concave friction pendulum system under variable vertical loading." Advances in Structural Engineering 22, no. 8 (February 19, 2019): 1998–2005. http://dx.doi.org/10.1177/1369433219831474.

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The double concave friction pendulum system has been recognized as an efficient device for decreasing the seismic response of a structure during an earthquake excitation. Previous studies have focused mainly on the properties of the double concave friction pendulum system under constant vertical loading, and the width of the hysteretic loop changed by the vertical ground motion is less considered. In view of this, a theoretical study of the double concave friction pendulum system under variable vertical loading is conducted in this article. Meanwhile, the properties of the hysteretic loops of the double concave friction pendulum system with different friction coefficients between the articulated slider with the upper and lower sliding surfaces are investigated. The results show that the hysteretic loops of the double concave friction pendulum system will be affected by the variation of the vertical loading and the difference of the friction coefficients between the articulated slider with the upper and lower sliding surfaces.

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Splith, T., A. Kaps, and F. Stallmach. "Phase plot of a gravity pendulum acquired via the MEMS gyroscope and magnetic field sensors of a smartphone." American Journal of Physics 90, no. 4 (April 2022): 314–16. http://dx.doi.org/10.1119/10.0009254.

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A gravity pendulum experiment in which a smartphone serves as pendulum bob and as measurement device is described. As the pendulum oscillates, the smartphone gyroscope and magnetometer sensors are used to simultaneously record the bob's angular velocity and angular displacement. While the angular velocity is measured directly via the gyroscope sensor, the angular displacement is deduced from the change of the magnetometer reading while the smartphone oscillates in the constant magnetic field of the Earth. These two independent measurements enable us to derive the phase space representation of the pendulum motion directly from experimental data. Further data analysis yields energy plots, including the periodic change between the pendulum's kinetic and potential energy and the energy dissipation due to friction. Detailed instructions on how to adopt the experiment, which is both suitable as a lecture demonstration as well as an instructional laboratory experiment, are provided in the supplementary material.

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Matta, Emiliano, and Rita Greco. "Modeling and design of tuned mass dampers using sliding variable friction pendulum bearings." Acta Mechanica 231, no. 12 (September 19, 2020): 5021–46. http://dx.doi.org/10.1007/s00707-020-02801-9.

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Abstract An effective vibration control device, the pendulum tuned mass damper (P-TMD), can be easily realized as a mass supported on rolling or sliding pendulum bearings. While the bearings’ concavity provides the desired gravitational restoring force, the necessary dissipative force can be obtained either from additional dampers installed in parallel with the bearings or from the same friction resistance developing within each bearing between the roller/slider and the rolling/sliding surface. The latter solution may prove cheaper and more compact but implies that the P-TMD effectiveness will be amplitude dependent if the friction coefficient is kept uniform along the rolling/sliding surface, as in conventional friction bearings. In this case, the friction P-TMD will be as efficient as a viscous P-TMD only at a given vibration level, with large performance reductions at other levels. To avoid this inconvenience, this paper proposes a new type of sliding variable friction pendulum (VFP) TMD, called the VFP-TMD, in which the sliding surface is divided into two concentric regions: a circular inner region, having the lowest possible friction coefficient and the same dimensions of the slider, and an annular outer region, having a friction coefficient set to an optimal value. A similar arrangement has been recently proposed to realize adaptive seismic isolation devices, but no specific application to TMDs is reported. To assess the VFP-TMD performance, first its analytical model is derived, rigorously accounting for geometric nonlinearities as well as for the variable (in time and space) pressure distribution along the contact area, and then, an optimal design methodology is presented. Finally, numerical simulations show the influence of the main design parameters on the device behavior and demonstrate that the VFP-TMD can achieve nearly the same effectiveness of viscous P-TMDs, while considerably outperforming conventional uniform-friction P-TMDs. The proposed analytical model can be used to enhance or validate existing models of VFP isolators that assume a constant and uniform contact pressure distribution.

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Sunarchin, Robert А., and Pavel V. Petrov. "Self-oscillation of the Froude pendulum (Numerical study)." Journal of Dynamics and Vibroacoustics 6, no. 1 (March 20, 2020): 35–42. http://dx.doi.org/10.18287/2409-4579-2020-6-1-35-42.

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A numerical study of the self-oscillation of the Froude friction pendulum is presented. For comparison with approximate analytical or graphical solutions, the cubic approximation is used as one of the approximations of the friction characteristic; changes in the case of other approximations are shown.By results of the conducted computational experiment was built characteristics of the amplitude of self-oscillations from dimensionless ratios, complexes of similarity, which showed the convergence of the estimated and actual (obtained by numerical integration) values of the amplitudes of oscillation for small values of friction and slope characteristics; if you increase the moment amplitude is also increased.It is noted that the results of computer modeling will significantly depend on the design, manufacturing technology and operating conditions of the device in question.

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Abed, Dana, Jafar Al Thawabteh, Yazan Alzubi, Jamal Assbeihat, and Eid Al-Sahawneh. "Influence of Earthquake Parameters on the Bi-directional Behavior of Base Isolation Systems." Civil Engineering Journal 8, no. 10 (October 1, 2022): 2038–52. http://dx.doi.org/10.28991/cej-2022-08-10-02.

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The introduction and development of the base isolation systems, especially the friction isolator device, were done recently to improve the capacity of adaptive behavior. The efficiency of multi-phase friction pendulums comes from their complexity, which helps reduce the structural responses and enhance structures' energy dissipation under lateral loads. Nevertheless, the influence of various earthquakes' properties on the behavior of base-isolation systems subjected to bi-directional seismic loading is still unclear. Hence, further research and studies regarding the behavior and capability of these systems under bi-directional loading are still necessary before incorporating this device in real-life practical applications. Therefore, this paper is intended to investigate the bi-directional behavior of the friction isolator subjected to various ground motion records. In order to do so, different versions of the friction pendulum system are selected and compared within the study context. Generally, the study's results have shown that the behavior of the friction isolator is highly dependent on low values of the PGA/PGV ratio. Besides, pulse-like earthquakes considerably impact the response of the isolator compared to non-pulse-like ones. Doi: 10.28991/CEJ-2022-08-10-02 Full Text: PDF

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Okamura, Shigeki, Satoshi Fujita, and Masayoshi Ikenaga. "Motion Analysis of Pendulum-Type Isolation Systems During Earthquakes: Dynamic Test and Response Analysis on a Three Story Steel Frame Model Supported by Four Friction Pendulum Bearings." Journal of Pressure Vessel Technology 126, no. 1 (February 1, 2004): 34–45. http://dx.doi.org/10.1115/1.1636789.

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After the Hanshin-Awaji Earthquake Disaster, the number of earthquake isolated buildings is increasing. Most of the base isolated buildings or structures are built on laminated rubber bearings in order to give them certain natural periods. This situation, however, also encourages structural engineers to research and develop nonrubber-type isolation systems such as linear motion bearing isolators and friction pendulum systems. It is considered that the nonrubber-type isolation systems can be applied to important industrial facilities, such as LNG tanks, boiler facilities and so on to refine their seismic reliabilities. In the device of the nonrubber-type isolation systems, the device which applied the sliding is especially noticed. However, when using nonrubber-type isolation systems with sliding in the open air circumstances, long term durability of the systems must be taken into account and it may be very difficult to maintain the friction coefficient of the system. In this study, the dynamic motion analysis and the experimental tests on the isolated structure mounted on four Friction Pendulum Bearing (FPB) Systems were carried out to investigate the performance of isolation due to the rotational motion which might be induced by the friction force difference in FPB system.

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Fenz, Daniel M., and Michael C. Constantinou. "Modeling Triple Friction Pendulum Bearings for Response-History Analysis." Earthquake Spectra 24, no. 4 (November 2008): 1011–28. http://dx.doi.org/10.1193/1.2982531.

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There are currently no applicable hysteresis rules or nonlinear elements available in structural analysis software that can be used to exactly model triple Friction Pendulum bearings for response-history analysis. Series models composed of existing nonlinear elements are proposed since they can be immediately implemented in currently available analysis software. However, the behavior of the triple Friction Pendulum bearing is not exactly that of a series arrangement of single concave Friction Pendulum bearings—though it is similar. This paper describes how to modify the input parameters of the series model in order to precisely retrace the true force-displacement behavior exhibited by this device. Recommendations are made for modeling in SAP2000 and are illustrated through analysis of a simple seismically isolated structure. The results are confirmed by (a) verifying the force-displacement behavior through comparison with experimental data and (b) verifying the analysis through comparison to the results obtained by direct numerical integration of the equations of motion.

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Kim, Woo Bum, Kangmin Lee, and Gil Hee Kim. "Application of friction pendulum system to the main control room of a nuclear power plant." Canadian Journal of Civil Engineering 36, no. 1 (January 2009): 63–72. http://dx.doi.org/10.1139/l08-111.

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An experimental and analytical study was performed to determine if the friction pendulum system (FPS) could be applied to the main control room (MCR) of a nuclear power plant as a seismic isolation device. A friction pendulum bearing was fabricated, and the dynamic performance of that bearing was evaluated. A partial model of the MCR with FPS was tested on a shaking table. The model consisted of a cabinet, an access floor, and four friction pendulum bearings. An artificial time history based on the MCR floor response spectrum was used as an earthquake input signal for the test. Analytical and experimental results were compared to verifiy their correlation and to enable the experimental study to cover a range of parametersnot previously studied in other similar experiments. Through these comparisons, it was affirmed that the proposed FPS seismic isolation system can be applied, with high reliability, to the MCR of a nuclear power plant.

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Alaci, Stelian, Ilie Muscă, and Ștefan-Gheorghe Pentiuc. "Study of the Rolling Friction Coefficient between Dissimilar Materials through the Motion of a Conical Pendulum." Materials 13, no. 21 (November 8, 2020): 5032. http://dx.doi.org/10.3390/ma13215032.

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The rolling friction phenomenon is encountered in a wide range of applications and when two different materials are involved, quantitative characterization is necessary. The parameter to be determined is the coefficient of rolling friction, for whose estimation a methodology is proposed, based on the damped oscillation of a conical pendulum. The pure rolling contact between a sphere and a plane is obtained when a steel ball is the bob of the pendulum, which rolls on an inclined plate made from a second material from the contacting pair. The mathematical model of the motion of a conical pendulum constructed from a revolution body supported on an inclined plane in the presence of the rolling friction is developed. The dynamic equations of the rigid body with fixed point are applied and the differential equation of motion of the pendulum is obtained together with the expressions of the reaction forces in the contact point. For different pairs of materials, tests are performed on a laboratory device. The damped oscillatory motion of the conical pendulum is video-captured for the estimation of the angular amplitude variation. A program for image processing is developed for measuring the values of angular elongations from the analysis of each frame of the video and, finally, the coefficient of rolling friction is obtained. For all the materials tested, a linear decrease in angular amplitude is detected and the slope of angular amplitude can be considered as a characteristic parameter related to the coefficient of rolling friction between the two materials.

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Gilavdary, Igor, Samir Mekid, and Natalia Riznookaya. "Phenomenological Laws of Single Point Contact: Pre-Rolling Contact Resistance through Pendulum." Lubricants 11, no. 2 (February 17, 2023): 88. http://dx.doi.org/10.3390/lubricants11020088.

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The development results of a single-point contact system set up as a pendulum to study the laws of rolling resistance to contacting bodies at a distance significantly reduced compared to the elastic contact spot size. The designed device uses a physical pendulum sustained by only one ball on a flat polished surface. The problem of stability of the pendulum swing plane is solved. A phenomenological theory of rolling resistance is described. The surface tension of solids on the contact zone, parameters of the frequency-independent internal friction and the pressure of the adhesion forces are found.

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Avossa, Alberto Maria, Danilo Di Giacinto, Pasquale Malangone, and Fabio Rizzo. "Seismic Retrofit of a Multispan Prestressed Concrete Girder Bridge with Friction Pendulum Devices." Shock and Vibration 2018 (2018): 1–22. http://dx.doi.org/10.1155/2018/5679480.

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The paper deals with the proposal and application of a procedure for the seismic retrofit of an existing multispan prestressed concrete girder bridge defined explicitly for the use of friction pendulum devices as an isolation system placed between piers top and deck. First, the outcomes of the seismic risk assessment of the existing bridge, performed using an incremental noniterative Nonlinear Static Procedure, based on the Capacity Spectrum Method as well as the Inelastic Demand Response Spectra, are described and discussed. Then, a specific multilevel design process, based on a proper application of the hierarchy of strength considerations and the Direct Displacement-Based Design approach, is adopted to dimension the FPD devices. Furthermore, to assess the impact of the FPD nonlinear behaviour on the bridge seismic response, a device model that reproduces the variation of the normal force and friction coefficient, the bidirectional coupling, and the large deformation effects during nonlinear dynamic analyses was used. Finally, the paper examines the effects of the FPD modelling parameters on the behaviour of the retrofitted bridge and assesses its seismic response with the results pointing out the efficiency of the adopted seismic retrofit solution.

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Li, Shanshan, Ping Xiang, Biao Wei, Chengjun Zuo, Lizhong Jiang, and Weikun He. "A Numerically Scaled Spring-Friction System and Validation by Shaking Table Test." International Journal of Structural Stability and Dynamics 21, no. 07 (March 27, 2021): 2150092. http://dx.doi.org/10.1142/s0219455421500929.

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The seismic isolation efficiency of different friction-based devices needs verification by shaking table test, but faces problems in scaling before the test due to their frictional nonlinearity. To solve the scaling problems, a simplified civil structure, isolated by a self-centering spring-friction device, was numerically scaled in different ways considering the effect of friction action. The seismic responses of the scaled models were scaled back to those of the prototype and compared with the seismic responses of the prototype. The scaling problems and solutions were validated by a shaking table test on simply supported bridges using friction pendulum bearings (FPBs). The results show that both the unscaled gravity on a shaking table and the unscaled non-uniform friction distribution cause an inaccurate friction force in the structural motion equations of scaled models, and thus causing the scaling errors. One new and valid solution, i.e. changing the friction coefficient and scaling the non-uniform friction distribution to keep an accurate friction force for the scaled models, is put forward to avoid the scaling errors thoroughly. Another new solution shows that an increasing peak ground acceleration (PGA) can increase the other forces, while weakening the ratio of inaccurate friction force in the structural motion equations of the scaled models, which therefore reducing the scaling errors of acceleration and relative displacement responses, but not the scaling errors of residual displacement responses. In addition, the time-varying friction, the interface separation and collision of bearings, and other complex factors are found to cause scaling errors and need further investigation.

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Okamura, Shigeki, and Satoshi Fujita. "Motion Analysis of Pendulum Type Isolation Systems During Earthquakes (Probabilistic Study of Isolation Performance of Base Isolated Structure Considering Characteristic Dispersion of Pendulum Type Isolation Systems)." Journal of Pressure Vessel Technology 129, no. 3 (July 5, 2006): 507–15. http://dx.doi.org/10.1115/1.2748831.

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Most of the base isolated buildings or structures are built on laminated rubber bearings in order to give them certain natural periods. This situation, however, also encourages structural engineers to research and develop nonrubber-type isolation systems such as linear motion bearing isolators and friction pendulum systems. It is considered that the nonrubber-type isolation systems can be applied to important industrial facilities, such as LNG tanks, boiler facilities, and so on, to refine their seismic reliabilities. This device of a nonrubber-type isolation system uses the energy loss associated with sliding to reduce the deleterious effects of earthquakes. However, when using nonrubber-type isolation systems with sliding in the atmosphere, long term durability of the systems must be taken into account. It may be difficult to maintain the friction coefficient of the system. In this paper, a stochastic study of the effect on rotational motion and isolation performance of two structures subjected to an earthquake with a friction pendulum bearing is analyzed with a Monte Carlo method.

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V. Awad, Susana, Joaquin F. Orozco, and Fredy E. Hoyos. "Measurement of low frequency mechanical vibrations based on an inverted magnetic pendulum." International Journal of Electrical and Computer Engineering (IJECE) 9, no. 5 (October 1, 2019): 3480. http://dx.doi.org/10.11591/ijece.v9i5.pp3480-3487.

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<span>In this paper is presented the mathematical model, design and construction of a prototype of a vibration frequency meter in an adjustable range of 2 Hz to 30 Hz; The experimental results and their analysis are also presented, making a comparative evaluation with the theoretical model. The device is based on the principle of resonance applied in an inverted magnetic pendulum whose natural frequency can be modified by variations of physical parameters. The oscillation of the pendulum is recorded detecting variations in the magnetic field using hall effect sensors; the data recorded with a microprocessor is analyzed and the results are simultaneously plotted in a computer interface. The data obtained were processed to be plotted in the frequency domain, facilitating its analysis. It was proved that the prototype can be used as a frequency meter and that the adjustable character of the device works according to the mathematical model. Finally, The effect of the friction force was studied, it was concluded that the friction force affects the measurement after a considerable period of time of oscillation, but not in the first moments.</span>

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Chen, Xu, and Jianfeng Xiong. "Seismic resilient design with base isolation device using friction pendulum bearing and viscous damper." Soil Dynamics and Earthquake Engineering 153 (February 2022): 107073. http://dx.doi.org/10.1016/j.soildyn.2021.107073.

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Kim, Kwonil, Woojin Han, Sanghyun Choi, Minseu Kim, Sungkook Cho, and Yang-Hee Joe. "Vibration Reduction Characteristics of a Mechanical Piping Support Device Based on Friction Pendulum Principle." Korean Society of Hazard Mitigation 16, no. 6 (December 31, 2016): 319–24. http://dx.doi.org/10.9798/kosham.2016.16.6.319.

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Chang, Huahui, Leifei Liu, Li Jing, Jingyan Lu, and Sasa Cao. "Study on Damping Performance of Hyperboloid Damper with SMA-Negative Stiffness." Buildings 12, no. 8 (July 28, 2022): 1111. http://dx.doi.org/10.3390/buildings12081111.

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To improve the limiting capacity of isolation bearings and reduce residual deformation, a new material shape memory alloy (SMA) was introduced into the damping device. SMA shape memory materials have shape memory effect, superelastic effect, and damping properties of metal alloys. Although the SMA isolation bearing can improve the self-resetting ability of the bridge, it will increase the internal force response of the substructure compared with the ordinary isolation bearing. To solve this problem, a new type of SMA negative stiffness hyperboloid shock absorber is proposed. The device is provided with restoring force by SMA cables, negative rigidity by two friction pendulum supports with opposite curved surfaces, and energy dissipation capacity by friction between the slider and the upper and lower steel plates. Theoretical derivation and finite element analysis results show that the damping device can not only provide the self-resetting ability of the bridge but also partially reduce the internal force response of the SMA damping bridge structural system on the premise of reducing the displacement response of the bridge.

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Antipova, L. V., S. A. Titov, V. N. Zhdanov, and A. N. Karpak. "The use of internal friction measurements for the study of ultra- and nanofiltration of modified curd whey." Proceedings of the Voronezh State University of Engineering Technologies 80, no. 4 (March 21, 2019): 298–303. http://dx.doi.org/10.20914/2310-1202-2018-4-298-303.

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A technique is proposed for the experimental determination of internal friction in food materials, as well as a device based on a torsion pendulum with laser registration of the angle of rotation, which ensures the minimum relative displacement of the layers of the material under study in the measurement process. The definition of internal friction is based on finding the attenuation of a torsion pendulum connected to a cylinder immersed in the medium under study. As an example of the application of the method to food systems, the dependence of internal friction on viscosity in solutions of sucrose and glycerin is determined. This dependence is linear for sucrose solutions and non-linear for glycerol solutions, which may be due to the interaction of hydrated molecules in solutions. Examples of the application of internal friction measurements in the study of membrane concentration processes are given. The method of internal friction was used as an auxiliary rheological method in a comprehensive study of the process of deposition of concentrated substances on membranes during ultra- and nanofiltration of whey. Thus, it has been shown that, despite the thinness in comparison with the membrane, the polarization layer makes a significant contribution to the internal friction of the membrane-layer system. This leads to a sharp decrease in the flow of curd whey filtrate through the membrane, compared with the flow of water under the same conditions. The dependence of internal friction on the concentration in the curd whey that underwent electroflotation treatment was determined, as well as the thermal isomerization of the lactose contained in it. Using such curves, the relationships between the permeability coefficient Lp * in the Kedem–Kachelsky equation and the parameters of the nanofiltration process of given food systems can be found.

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Gilavdary, I. Z., S. Mekid, and N. N. Riznookaya. "Device and Measuring Method the Moments of Rolling Resistance Forces on the Contact Spot." Devices and Methods of Measurements 10, no. 4 (December 12, 2019): 308–21. http://dx.doi.org/10.21122/2220-9506-2019-10-4-308-321.

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Currently, the study of rolling friction is one of the main directions in the study of the laws of contact interaction of solids. The complexity of solving the problems existing in this area is evidenced by the practically vast number of publications, the list of which is constantly growing.In this paper, attention is paid to studies of the moments of rolling resistance at displacements from the equilibrium position of a ball-shaped body that are substantially smaller than the size of the contact spot. The purpose of the present work is to describe the design of the single-contact pendulum device developed by the authors, in which the physical pendulum, resting on the flat surface of the body under study with only one ball, makes free small stable swings in a vertical plane, as well as in the description of a special measurement technique with high sensitivity and accuracy rolling resistance forces, including adhesion forces and frequency-independent forces of elastic deformations. It is assumed that the adhesion forces can exhibit both dissipative properties and elastic properties, while elastic forces are independent of the strain rate.The originality of the method of measuring rolling resistance in this paper consists in using the method of nonlinear approximation of the dependence of the amplitude and period of swing of the pendulum on time. The approximation is carried out on the basis of the proposed laws of amplitude decay and period variation, which differ from the usual exponential law.It is assumed that this approach allows one to evaluate the surface tension of a solid and evaluate the pressure of adhesion forces between the surfaces of the contacting bodies, as well as to establish an analytical form of the moment of rolling resistance. The curves of the dependence of the rolling resistance moment on the swing amplitude of the pendulum are constructed. Experiments were performed for the following pairs of contacting bodies: steel-steel, steel-glass, steel-electritechnical silicon. It was assumed that the pressure at the contact spot did not exceed the elastic limit.The developed single-ball pendulum device and the proposed measurement procedure open up new wide possibilities for studying the laws of mechanisms of rolling resistance under conditions of microand mesoscale displacements of a rolling body from a state of rest.

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Ozbulut, Osman E., and Stefan Hurlebaus. "A Comparative Study on the Seismic Performance of Superelastic-Friction Base Isolators against Near-Field Earthquakes." Earthquake Spectra 28, no. 3 (August 2012): 1147–63. http://dx.doi.org/10.1193/1.4000070.

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This paper presents a comparative seismic performance assessment of super-elastic-friction base isolator (S-FBI) systems in improving the response of bridges under near-field earthquakes. The S-FBI system consists of a steel-Teflon sliding bearing and a superelastic shape memory alloy (SMA) device. The other isolation systems considered here are lead rubber bearing (LRB), friction pendulum system (FPS), and resilient-friction base isolator (R-FBI). Each isolation system is designed to provide the same isolation period and characteristic strength. Nonlinear time-history analyses of an isolated bridge are performed to compare the performance of various isolation systems. The results indicate that the S-FBI system shows superior performance in reducing deck displacement response and effectively limits permanent bearing deformation, whereas residual deformations are present for the other isolation systems in some cases. It is also observed that the LRB system has the largest deck drifts while the FPS system and R-FBI system produce the smallest peak deck acceleration and base shear.

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Robinson, William H. "The Roball." Bulletin of the New Zealand Society for Earthquake Engineering 35, no. 3 (September 30, 2002): 204–7. http://dx.doi.org/10.5459/bnzsee.35.3.204-207.

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Robinson Seismic's latest developments in seismic isolation includes a new device, the RoballTM, for seismically isolating structures during earthquakes. This advance is a new concept for seismic isolation based on the principle of the inverted pendulum. It consists of 'friction balls' or 'Roballs' moving between upper and lower spherical like cavities or flat plates. The Roballs are filled with a material which is able to provide the friction forces required to absorb the energy from numerous earthquakes while supporting the structure. The Roball technique is expected to enable light and in the future possibly heavy structures to be more economically seismically isolated. As part of a program to develop a user friendly 'seismic isolation system' a series of full-scale tests have been carried out on a number of possible designs including three approaches for vertical pressures of -1 MPa resulting in coefficients of friction of -0.1 to -0.4. In this paper we present the preliminary experimental results.

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TAYMUŞ, Refik Burak, and İbrahim AYDOĞDU. "Effect of Seismic Isolation with Triple Friction Pendulum Isolator Device on Weight Optimization of Steel Plane Frames." International Journal of Engineering and Applied Sciences 13, no. 3 (December 9, 2021): 79–92. http://dx.doi.org/10.24107/ijeas.996630.

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Peng, Tianbo, Jianyu Guan, and Yicheng Wu. "Numerical and Experimental Investigation of the Seismic Effect of a Two-Stage Seismic Isolation Method." Sustainability 15, no. 6 (March 9, 2023): 4883. http://dx.doi.org/10.3390/su15064883.

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In order to improve the post-earthquake resilience of bridge structures, a Two-Stage seismic isolation method is proposed in this paper. According to the method, the restoring force and horizontal stiffness are smaller in the first stage and become much larger in the second stage. Therefore, a new kind of seismic isolation device, Two-Stage Friction Pendulum Bearing (TSFPB for short), is invented based on the traditional friction pendulum bearing (FPB for short). In this paper, the geometry configuration, sliding states and hysteresis characteristics of the bearing are first introduced with a theoretical approach. Then the hysteresis curve of the TSFPB is verified experimentally and the simulation method of the bearing in an FEM software is proposed. Last, a numerical analysis for an actual highway girder bridge is carried out to compare the seismic design method recommended in this paper with the conventional seismic isolation method. It is found that the Two-Stage seismic isolation method has an adaptive restoring force, horizontal stiffness and energy dissipation mechanism for different seismic intensity levels and better seismic performance compared with a conventional seismic isolation method. In addition, bridges with TSFPBs have smaller residual displacements and better post-earthquake resilience than those with traditional FPBs.

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Ivoilov, A. Yu, V. A. Zhmud, V. G. Trubin, and H. Roth. "Parametric Synthesis of the Control System of the Balancing Robot by the Numerical Optimization Method." Mekhatronika, Avtomatizatsiya, Upravlenie 20, no. 6 (June 6, 2019): 352–61. http://dx.doi.org/10.17587/mau.20.352-361.

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This article is devoted to parametric synthesis of a control system of a two-wheeled balancing robot. From the mathematical point of view, the robot is an inverted pendulum type object with a pivot point placed on the wheel axis. This device is unstable while deenergized. Devices of this type are excellent labor atory stands for testing and debugging control algorithms of unstable nonlinear systems. The inverted pendulum math model is well studied theoretically but, when designing a particular device many additional tasks arise such as taking into account the error in measuring the tilt angle and the influence of actuator nonlinearities. In this paper, one of these tasks is solved, namely, the problem of reducing the amplitude of the robot’s oscillation around the equilibrium position. In practice, this oscillation almost always occurs in such systems and leads to various negative effects, such as increased energy consumption, increased wear of an actuator and heating of its windings, etc. Therefore, reducing the amplitude of the oscillation is an important task. To solve this task, the authors of the article propose to use the method of numerical optimization of the regulator, which is well recommended for solving many problems. The article analyzes the behavior of the device near the equilibrium position and identifies the causes of the self-oscillation. Further the method of its simulation is proposed. On the basis of numerical experiments, the main reason for the increase in the amplitude of the oscillation is revealed. The reason is an overlay of the reverse peak of the device transient process on the peak caused by a torque throw. The throw is generated by a combination of actuator backlash and static friction effects which cause the robot self-oscillation. The authors propose a technique of adjusting the regulator, aimed at reducing the magnitude of the reverse peak of the transition process and, as a consequence, reducing the amplitude of the oscillation. The effectiveness of the technique is confirmed experimentally by the results of numerical simulation of the robot’s behavior and the results of testing the coefficients obtained in a real device. The use of the technique allowed reducing the oscillation amplitude in a real device by almost three times.

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Smirnov, Alexey S., and Alexander S. Muravyov. "Optimization of oscillation damping in systems with a non-integer number of degrees of freedom." Vestnik of Saint Petersburg University. Mathematics. Mechanics. Astronomy 9, no. 1 (2022): 164–75. http://dx.doi.org/10.21638/spbu01.2022.116.

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The paper discusses issues related to the choice of the optimal damping for a system with one and a half degrees of freedom - a pendulum with an elastic-movable suspension point in the presence of viscous friction. Maximization of the degree of stability of the system is taken as an optimization criterion characterizing the efficiency of damping oscillations. Two options for installing a damping device are discussed - either in the pendulum joint, or parallel to the elastic element. The analytical solution of the optimization problem is performed in each case, and it is accompanied by a visual graphic illustration. In addition, a comparison of two cases of damping is given on the basis of analysis of the maximum degree of stability and a conclusion about the advisability of using one or another option is made. The obtained results are of interest both in theoretical and practical terms, and the described plan for finding the optimal solution can also be applied to solving other optimization problems in systems with a non-integer number of degrees of freedom.

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Do, Minh-Tan, Hassan Zahouani, and Roberto Vargiolu. "Angular Parameter for Characterizing Road Surface Microtexture." Transportation Research Record: Journal of the Transportation Research Board 1723, no. 1 (January 2000): 66–72. http://dx.doi.org/10.3141/1723-09.

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Development of a device for measuring road surface microtexture and the determination of a microtexture parameter related to wet road/tire friction are discussed. A laser autofocus system was selected from existing devices. The required characteristics were defined from consideration of the contact between wet roads and tires. The autofocus principle is presented briefly, and comparison is made with a tactile system. The microtexture parameter, called the theta parameter, is defined from the useful parts of the texture profiles, that is, those in contact with the tire. It characterizes relative positions of profile peaks. A simple method was proposed to define the peaks. The profile analysis program is presented briefly. Relevance of the theta parameter was validated on surfaces composed of coarse aggregates with planar exposed faces. The specimens were polished using a projection method to emphasize the microtexture contrast between surfaces. Friction was measured using a skid resistance tester (SRT) pendulum. Profiles were measured using both laser and tactile systems. Characteristics of profiles are given. The statistical distribution of theta values obtained on a profile may be described by an exponential function. Close agreement was found between theta values obtained from laser and tactile profiles, values from laser profiles being somewhat lower. The difference is attributed to profile length. Fair correlation was found ( r2 > 0.80) between theta values and SRT friction, and similar tendencies were observed from laser and tactile data.

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Li, Xiaodong, Qitai Wang, and Guangtian Ma. "Mechanical Properties of a Novel Plastic Hinge Seismic Fuse Based on Frictional Energy Dissipation to Avoid Brittle Failures in Beam-to-Column Moment-Resistant Joints." Arabian Journal for Science and Engineering 45, no. 5 (October 29, 2019): 3695–706. http://dx.doi.org/10.1007/s13369-019-04214-w.

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Abstract Traditional steel structure joints are prone to brittle failure under seismic excitation, and it is difficult to precisely control the location of the resulting plastic hinge or repair these joints after an earthquake. Therefore, based on the energy dissipation principle of the friction pendulum isolation bearing and automobile braking device, a low-cost friction-based plastic hinge (PH) joint is proposed to provide predictable energy dissipation and realize quickly repairable structures. The proposed PH was analysed theoretically, and five half-scale specimens using different bolt and friction materials were tested using cyclic reversing load. The test results showed that models PH-1 and PH-2 with Grade 4.8 and 8.8 limiting bolts, respectively, both provided a plastic rotation angle greater than 0.03 rad, exhibited experimental moment capacities of 0.91 and 0.93 times their theoretical capacities, and exhibited ductility coefficients of 2.75 and 3.14, respectively. It was found that high-strength limiting bolts were unsuitable as they damaged difficult-to-replace PH components. The selected PH configuration experienced damage to only the limiting bolts and friction plates and exhibited good plastic deformation capacity and hysteretic energy dissipation performance that met the plastic rotation, ductility, and friction energy dissipation requirements. Thus, the proposed PH can be used to improve the seismic performance of beam-to-column joints and the frames they form.

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Kim, Sung-Wan, Bub-Gyu Jeon, Da-Woon Yun, Woo-Young Jung, and Bu-Seog Ju. "Seismic Experimental Assessment of Remote Terminal Unit System with Friction Pendulum under Triaxial Shake Table Tests." Metals 11, no. 9 (September 9, 2021): 1428. http://dx.doi.org/10.3390/met11091428.

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In recent years, earthquakes have caused more damage to nonstructural components, such as mechanical and electrical equipment and piping systems, than to structural components. In particular, among the nonstructural components, the electrical cabinet is an essential piece of equipment used to maintain the functionality of critical facilities such as nuclear and non-nuclear power plants. Therefore, damage to the electrical cabinet associated with the safety of the facility can lead to severe accidents related to loss-of-life and property damage. Consequently, the electrical cabinet system must be protected against strong ground motion. This paper presents an exploratory study of dynamic characteristics of seismically isolated remote terminal unit (RTU) cabinet system subjected to tri-axial shaking table, and also the shaking table test of the non-seismically isolated cabinet system was conducted to compare the vibration characteristics with the cabinet system installed with friction pendulum isolator device. In addition, for the shaking table test, two recorded earthquakes obtained from Korea and artificial earthquakes based on the common application of building seismic-resistant design standards as an input ground motions were applied. The experimental assessment showed that the various damage modes such as door opening, the fall of the wire mold, and damage to door lock occurred in the RTU panel fixed on the concrete foundation by a set anchor, but the damage occurred only at the seismic isolator in the seismically isolated RTU panel system. Furthermore, it was considered that the application of the seismic isolator can effectively mitigate the impact and amplification of seismic force to the RTU panel system during and after strong ground motions in this study.

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Matta, Emiliano, Rosario Ceravolo, Alessandro de Stefano, Antonino Quattrone, and Luca Zanotti Fragonara. "Unscented Kalman Filter for Non-Linear Identification of a New Prototype of Bidirectional Tuned Vibration Absorber: A Numerical Investigation." Key Engineering Materials 569-570 (July 2013): 948–55. http://dx.doi.org/10.4028/www.scientific.net/kem.569-570.948.

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Several nonlinear system identification methods have been presented in the past, such as the Extended Kalman Filter, the H filter and the Sequential Monte Carlo methods. One of the most promising ones is the Unscented Kalman Filter (UKF) recently proposed for the on-line identification of structural parameters. In the present study the UKF is proposed to the purpose of the nonlinear identification of a new prototype of rolling-pendulum tuned vibration absorber which, relying on an optimal three-dimensional guiding receptacle, can simultaneously control the response of the supporting structure along two orthogonal horizontal directions. Unlike existing ball vibration absorbers, mounted on spherical recesses and used in axial-symmetrical structures, the new device can be bidirectionally tuned to both fundamental structural modes even when the corresponding natural frequencies are different, by virtue of the optimum shape of the rolling cavity. Based on preliminary numerical simulations, the UKF is shown to be effective in identifying the structural parameters of the new device and particularly the nonlinear rolling friction dissipation mechanism at the interface between the ball bearing and the rolling surface.

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33

Hosseini, Ahmad, and Morteza Esmaeili. "Effect of different contact surfaces between concrete sleeper and ballast on mobilized lateral resistance against impact loads." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 231, no. 6 (March 7, 2016): 678–89. http://dx.doi.org/10.1177/0954409716636924.

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The amount of ballast particles surrounding a railway track significantly influences its resistance in all directions. As time goes by, with the development of high-speed trains, more attention has been paid to this issue owing to the increase in dynamic effects of rolling stock on track loading. The focus of the present study is on the investigation of the interaction between different surfaces (base, crib, and shoulder) of concrete sleeper and their adjacent ballast layer along with the related parameters under lateral impact loading condition. In this regard, by utilizing a pendulum loading test device, a number of lateral impact tests were conducted on an instrumented concrete sleeper in laboratory. On the basis of experimental results, the average contribution of base, crib, and shoulder zones in the total dynamic lateral resistance of sleeper was calculated as 48%, 23%, and 29%, respectively. Furthermore, in the lateral impact force domain of 13–28 kN, the sleeper–ballast dynamic friction coefficient at base and crib zones varied in the ranges 0.8–1.5 and 0.5–0.6. Moreover, a maximum impact factor of 2.5 was obtained for analysis and design purposes. It should be stated that the trend of laboratory results confirmed the common static friction coefficient of 0.8.

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34

Streicher, R. M., M. Semlitsch, R. Schön, H. Weber, and C. Rieker. "Metal-On-Metal Articulation for Artificial Hip Joints: Laboratory Study and Clinical Results." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 210, no. 3 (September 1996): 223–32. http://dx.doi.org/10.1243/pime_proc_1996_210_416_02.

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As wear is inevitable with artificial joint replacement, it has to be minimized to avoid possible aseptic loosening following osteolysis due to particle-initiated foreign body reaction. Co-Cr-Mo-C alloys have a long history with only minimum wear when articulating with themselves. This investigation shows that the choice of the alloy has an effect on the wear rate of this articulation couple. Tribological studies in a screening device, a pendulum apparatus and a hip joint simulator showed a marked influence of the environment as well as the diameter of the implants with metal-on-metal articulation. A wear-resistant combination with low friction characteristics has been developed by using a wrought Co-Cr-Mo-C alloy and reducing the implant diameter to 28 mm. Clinical wear rates are comparable with laboratory data and demonstrate the potential of the metal-on-metal articulation to solve the problem of wear-induced osteolysis of hip joint endoprostheses.

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35

Abbassi, Saeed. "Impacts of vehicle tire on slip resistance and sound pollution in asphalt pavements." BEN Vol:2 Issue:3 2021 2, no. 3 (February 27, 2021): 16–21. http://dx.doi.org/10.36937/ben.2021.003.004.

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Noise pollution caused by vehicle traffic is one of the major problems in urban areas with road expansion. Due to the increase in the cost of construction and installation of sound walls to deal with noise pollution, to deal with this problem should look for methods that do not have additional costs and operating costs. Improving the pavement texture is one of the most effective ways to reduce tire noise and pavement and reduce the asphalt surface’s sound. To evaluate the slip resistance of asphalt, the English pendulum test according to ASTM E303-74 standard was performed on wet parts of asphalt in wet conditions. This device is used to examine the fine texture of the pavement. The number of pavement friction with a negative coefficient of 0.1469 has an inverse ratio with the intensity of sound level increases the number of pavement friction aligned with the amount of sound level created decreases. On the other hand, the depth of pavement texture, which is determined as the size of pavement materials, with a coefficient of 0.2810, has a direct ratio with the amount of noise pollution, and the smaller the number of fine-grained materials used will increase the sound level. According to the results of the coefficients estimated from the equation, it can be concluded that the preparation of pavements with an amount of friction can reduce the amount of noise pollution emitted by the movement of vehicles, especially in urban areas and sensitive areas. Therefore, it is recommended that in acoustically sensitive areas, in preparing pavements, arrangements be made to use coarser materials and maintain proper pavement resistance. For this purpose, in this article, the pavement’s texture is examined in the amount of noise created due to the tire’s interaction and the pavement.

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FUJITA, Satoshi, Hiromichi YAMAMOTO, Nobuhiro KITAGAWA, and Hiroshi kURABAYASHI. "Research and Development of the Friction Pendulum Isolation Device with Poly-Curvature (Investigation of Isolation Performance on Shake Test and Response Analysis Using Vending Machine Model)." Transactions of the Japan Society of Mechanical Engineers Series C 69, no. 684 (2003): 1990–96. http://dx.doi.org/10.1299/kikaic.69.1990.

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Cicolani, Luigi, Christina Ivler, Carl Ott, Reuben Raz, and Aviv Rosen. "Rotational Stabilization of Cargo Container Slung Loads." Journal of the American Helicopter Society 60, no. 4 (October 1, 2015): 1–13. http://dx.doi.org/10.4050/jahs.60.042006.

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The stabilization of “difficult” loads that become aerodynamically unstable at airspeeds well below the power-limited speed of the helicopter-load configuration has been studied since the 1960s. This paper looks at the possibility of stabilizing slung loads in forward flight by imposing a slow steady rotation in yaw (spin stabilization). Slow rotations of 100–150 deg/s suffice to suppress the pendulum motions of the load. A swivel is required at the hook, and only a few foot-pounds of yaw moment are needed to overcome swivel friction and impose the desired yaw rate. The approach is limited to single-point suspensions. A stabilizer design consisting of a one-shaft anemometer-like device with hemispherical cups at the ends was developed in wind tunnel tests. The shaft angle can be controlled to vary the applied yaw moment and allow feedback regulation of the load yaw rate. Flight tests with two cargo containers demonstrated that a simple linear control law with fixed gains was effective in maintaining the desired yaw rate in forward flight over the range of configurations of the test loads. Wind tunnel data were obtained at all stages of the development and testing and proved to be an accurate source of design data and an accurate predictor of performance in flight.

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Ziyakaev, Grigoriy R., M. V. Gorbenko, T. I. Gorbenko, and O. P. Ivkina. "Friction Influence on the Accuracy of the Rotors Automatic Balance." Key Engineering Materials 685 (February 2016): 441–44. http://dx.doi.org/10.4028/www.scientific.net/kem.685.441.

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In the given paper the influence of friction forces in the bearing on the accuracy of automatic balancing unbalanced rotors by pendular automatic balance devices is considered. Magnitude of residual offset of a rotor–pendulums system depending on the friction forces is received, that allows defining residual vibration of the mechanism.

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Han, Qiang, Jianian Wen, Zilan Zhong, and Xiuli Du. "Numerical Simulation of Frictional Heating Effects of Sliding Friction Bearings for Isolated Bridges." International Journal of Structural Stability and Dynamics 18, no. 08 (August 2018): 1840008. http://dx.doi.org/10.1142/s0219455418400084.

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Sliding friction bearings are effective passive devices to mitigate the seismic responses of structures. Extensive researches have been conducted on sliding bearings. However, most previous studies were based on the assumption that the effects of frictional heating are negligible. A three-dimensional thermal-mechanical-coupled finite element (FE) model of the friction pendulum system (FPS) was developed in this study. Good agreements between the numerical results and the data measured in the previous tests, in terms of the force–displacement curves and temperature time-histories, indicate that the proposed FE model can predict the response of the FPS. Based on the developed FE model, the surface temperature distribution, the effective stiffness and the energy dissipation of the double concave friction pendulum and multiple friction pendulum bearings were investigated and compared. In addition, the thermal states of the sliding bearings in the bridge during earthquake were evaluated. The numerical results indicate that the temperature rise in the sliding bearings leads to the degradation of the effective stiffness and less energy dissipation. The relative displacements of the bearings increase considering the frictional heating effects in the bearings. If the frictional heating of the bearings is ignored, the peak bearing displacements will be underestimated.

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Gino, Diego, Elena Miceli, and Paolo Castaldo. "Seismic reliability analysis of isolated deck bridges using friction pendulum devices." Procedia Structural Integrity 44 (2023): 1435–42. http://dx.doi.org/10.1016/j.prostr.2023.01.184.

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41

Nikolaev, V. I., A. V. Beletzky, D. V. Charnashtan, and S. F. Ermakov. "MODELING AND ESTIMATION OF SYNOVIAL JOINT FRICTION PROCESS." Health and Ecology Issues, no. 2 (June 28, 2008): 100–104. http://dx.doi.org/10.51523/2708-6011.2008-5-2-22.

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The tribological characteristics of a model «cartilage-cartilage» pair friction at presence of various lubricating medium has been investigated. A computerized pendular tribometer for an estimation of the friction processes in the joints of living organisms has been proposed. It is shown an effectiveness of a made precise pendular device by the example of investigation of lubricating behaviour of natural synovial fluid and it substitute on the base of blood serum.

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42

Kamrava, Alireza. "Seismic Isolators and their Types." Current World Environment 10, Special-Issue1 (June 28, 2015): 27–32. http://dx.doi.org/10.12944/cwe.10.special-issue1.05.

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In this paper I would like to describe about what seismic isolation is., seismic isolators, their types ,how do they work? ,their advantage and disadvantage. In seismic isolator types you will read about Elastomeric bearings, Natural and Synthetic Rubber Bearings , Lead Rubber Bearings , Friction pendulum bearing, Supplymetal Damping Devices like Buckling Restrained Brace, Fluid Dampers, Visco-Elastic Dampers,Friction Dampers, Hysteretic Dampers(Yeilding Dampers).In advantage and disadvantage part you will read some tips about using seismic isolators. In conclusion you will read a review about seismic isolation and using seismic isolators.

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Mojolic, C. "Numerical studies regarding the behaviour a large span roof under seismic load when using anti-seismic devices." IOP Conference Series: Materials Science and Engineering 1242, no. 1 (April 1, 2022): 012024. http://dx.doi.org/10.1088/1757-899x/1242/1/012024.

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Abstract The study presents the data obtained on a large span structure equipped with passive seismic isolators, placed at roof level, when subjected to multiple seismic loads. Three distinct passive isolation systems are taken into consideration to reduce the seismic response of the structure. The first case uses Friction Pendulum Systems (FP), the second uses a combination of High Damping Rubber Bearing (HDRB) and low friction pot-bearing systems, and the third implies the use of Lead Rubber Bearings (LRB) and low friction pot-bearing systems. Using seven sets of accelerograms, recorded and generated, the values for the main seismic response parameters are extracted in to underline the efficiency of the proposed systems. The results obtained in terms of natural vibration period, accelerations, bending moment, base shear are compared.

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Gino, Diego, Costanza Anerdi, Paolo Castaldo, Mario Ferrara, Gabriele Bertagnoli, and Luca Giordano. "Seismic Upgrading of Existing Reinforced Concrete Buildings Using Friction Pendulum Devices: A Probabilistic Evaluation." Applied Sciences 10, no. 24 (December 16, 2020): 8980. http://dx.doi.org/10.3390/app10248980.

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In many countries around the world a huge number of existing reinforced concrete (RC) structures have been realized without account for seismic detailing, even if they are located in areas subjected to high seismicity. In this context, several passive seismic protection techniques have been developed and applied to retrofit these structures such as, for an example, seismic isolation. The aim of this work is to characterize in probabilistic terms the seismic performance of a framed RC building retrofitted by means of sliding friction pendulum (FPS) devices. Specifically, the response of an existing RC building located in a high seismicity area in Italy is investigated. After the description of the main available information about the structure, a non-linear numerical model has been defined by means of fiber-elements approach. Then, non-linear dynamic analyses considering multiple recorded ground motions with the three accelerometric components have been carried out to assess the seismic response of the building with and without the retrofitting intervention composed of FPS isolators. Finally, the results are processed to achieve a probabilistic assessment of the seismic performance of the retrofitting intervention.

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Castaldo, Paolo, Bruno Palazzo, and Tatiana Ferrentino. "Seismic reliability-based ductility demand evaluation for inelastic base-isolated structures with friction pendulum devices." Earthquake Engineering & Structural Dynamics 46, no. 8 (December 19, 2016): 1245–66. http://dx.doi.org/10.1002/eqe.2854.

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Castaldo, Paolo, Guglielmo Amendola, and Bruno Palazzo. "Seismic fragility and reliability of structures isolated by friction pendulum devices: seismic reliability-based design (SRBD)." Earthquake Engineering & Structural Dynamics 46, no. 3 (August 22, 2016): 425–46. http://dx.doi.org/10.1002/eqe.2798.

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Avinash, A. R., A. Krishnamoorthy, Kiran Kamath, and M. Chaithra. "Sliding Isolation Systems: Historical Review, Modeling Techniques, and the Contemporary Trends." Buildings 12, no. 11 (November 16, 2022): 1997. http://dx.doi.org/10.3390/buildings12111997.

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Base isolation techniques have emerged as the most effective seismic damage mitigation strategies. Several types of aseismic devices for base isolation have been invented, studied, and used. Out of several isolation systems, sliding isolation systems are popular due to their operational simplicity and ease of manufacturing. This article discusses the historical development of passive sliding isolation systems, such as pure friction systems, friction pendulum systems, and isolators with other sliding surface geometries. Moreover, multiple surface isolation systems and their behavior as well as the effectiveness of using complementary devices with standalone passive isolation devices are examined. Furthermore, the article explored the various modeling techniques adopted for base-isolated single and multi-degree freedom building structures. Special attention has been given to the techniques available for modeling the complex phenomena of sliding and non-sliding phases of sliding bearings. The discussion is further extended to the development in the contemporary areas of seismic isolation, such as active and hybrid isolation systems. Although a significant amount of research is carried out in the area of active and hybrid isolation systems, the passive sliding isolation system still has not lost its appeal due to its ease of adaptability to the structures.

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Castaldo, Paolo, and Tatiana Ferrentino. "Seismic Reliability-Based Design Approach for Base-Isolated Systems in Different Sites." Sustainability 12, no. 6 (March 19, 2020): 2400. http://dx.doi.org/10.3390/su12062400.

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This study employs the seismic reliability-based design approach for inelastic structures isolated by friction pendulum isolators, considering two different highly seismic Italian sites to provide useful design recommendations. Incremental dynamic analyses are carried out to estimate the seismic fragility of the superstructure and of devices, assuming different structural properties and limit state thresholds. Finally, considering seismic hazard curves of the investigated sites, seismic reliability-based design curves are proposed to derive the dimensions in plan of devices and the ductility demand of the superstructure as a function of both the structural properties and the reliability level expected. The proposed results confirm the possibility of using seismic reliability-based design as a sustainable and applicable approach and represent a large data set to adopt this design methodology in any site with a similar seismic hazard.

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Nuraini, Santi, Asdam Tambusay, and Priyo Suprobo. "A comparative study of base isolation devices in light rail transit structure featured with lead rubber bearing and friction pendulum system." MATEC Web of Conferences 195 (2018): 02013. http://dx.doi.org/10.1051/matecconf/201819502013.

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Advanced nonlinear analysis in light rail transit (LRT) structures has been undertaken to examine the influence of seismic isolation devices for reducing seismic demand. The study employed the use of two types of commercially available bearings, namely lead rubber bearing (LRB) and friction pendulum system (FPS). Six LRT structures, designed to be built in Surabaya, were modelled using computer-aided software SAP2000, where each of the three structures consisted of three types of LRB and FPS placed onto the pier cap to support the horizontal upper-structural member. Nonlinear static pushover and dynamic time history analysis with seven improved ground motion data was performed to gain improved insights on the behavioural response of LRT structures, allowing one to fully understand the supremacy of seismic isolations for protecting the structure against seismic actions. It is shown that both devices manage to isolate seismic forces, resulting in alleviation of excessive base shear occurring at the column. In addition, it is noticeable that the overall responses of LRB and FPS shows marginal discrepancies, suggesting both devices are interchangeable to be used for LRT-like structures.

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Bagheri, Saman, and Mostafa Farajian. "The effects of input earthquake characteristics on the nonlinear dynamic behavior of FPS isolated liquid storage tanks." Journal of Vibration and Control 24, no. 7 (June 20, 2016): 1264–82. http://dx.doi.org/10.1177/1077546316655914.

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There are several methods to reduce the seismic damages in liquid storage tanks. One of these methods is to use passive control devices, in particular seismic base isolators. Among the different base isolation systems, the Friction Pendulum System (FPS) whose period does not depend on the weight of the system is more appropriate for isolation of liquid storage tanks. The aim of this paper is to investigate the effects of peak ground acceleration (PGA) and pulselike characteristics of earthquakes on the seismic behavior of steel liquid storage tanks base isolated by FPS bearings. In addition, impact effects of the slider with the side retainer are investigated, as well as effects of tank aspect ratio, isolation period and friction coefficient. The obtained results of tanks with different aspect ratios indicate that the responses get more reduced due to isolation under far-field ground motions compared to near-fault ground motions. It is also seen that the response of a base isolated tank is affected when contact takes place with the side retainer of the FPS.

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Journal articles on the topic 'Friction Pendulum Device'

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