The Velocity Evolution of an Isolated Element in a Friction Pendulum for Different Sliding Surfaces

2017 ◽  
pp. 405-410
Author(s):  
Gelu Balan ◽  
Tiberiu Manescu ◽  
Camelia Jurcau ◽  
Ovidiu Milos ◽  
Vasile Iancu
Keyword(s):  
Sliding Surfaces ◽  
Friction Pendulum

Theoretical study of the double concave friction pendulum system under variable vertical loading

2019 ◽  
Vol 22 (8) ◽  
pp. 1998-2005 ◽  
Author(s):  
Fangyuan Zhou ◽  
Weilin Xiang ◽  
Kun Ye ◽  
Hongping Zhu
Keyword(s):  
Theoretical Study ◽  
Earthquake Excitation ◽  
Friction Coefficients ◽  
Pendulum System ◽  
Vertical Loading ◽  
Sliding Surfaces ◽  
Vertical Ground ◽  
The Difference ◽  
Friction Pendulum ◽  
Friction Pendulum System

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.

Behavior of Quintuple Friction Pendulum System Under Near-Fault Earthquakes

2017 ◽  
Vol 11 (05) ◽  
pp. 1750017
Author(s):  
A. H. Sodha ◽  
D. P. Soni ◽  
M. K. Desai ◽  
S. Kumar
Keyword(s):  
Adaptive Behavior ◽  
Service Level ◽  
Base Shear ◽  
Pendulum System ◽  
Directivity Effect ◽  
Sliding Surfaces ◽  
Near Fault ◽  
Effective Period ◽  
Fling Step ◽  
Friction Pendulum

The Quintuple Friction Pendulum (QTFP) system is a new generation sliding isolation having six spherical sliding surfaces with five effective pendula. Due to multiple sliding surfaces, QTFP system shows highly adaptive behavior under different hazard level of earthquakes, despite being a passive system. The paper describes mathematical model and seismic response of QTFP system under 60 earthquake records consisting of service level, design basis and maximum considered earthquakes. To study the effect of directivity focusing and fling step, additional 15 records consist of far-field, near-fault with forward directivity and fling step effect are also considered. Three types of effective period and effective damping in combination with two different displacement capacities of QTFP bearing resulting in six isolator designs are considered. The seismic demand parameters like base shear, top floor absolute acceleration and isolator displacement have been studied. It is found that the QTFP bearing stiffens at low input, softens with increasing input, and then stiffens again at higher levels of input. Thus, it shows highly adaptive behavior under different hazard levels of earthquake. Further, due to forward and backward momentum conveyed by the directivity pulse, near-fault directivity effect imposes higher demand compared to fling step containing only forward momentum.

scholarly journals Shaking table tests of a base isolated structure with Double Concave Friction Pendulum bearings

2015 ◽  
Vol 48 (2) ◽  
pp. 136-144 ◽  
Author(s):  
Felice C. Ponzo ◽  
Antonio D. Cesare ◽  
Gianmarco Leccese ◽  
Domenico Nigro
Keyword(s):  
Base Isolation ◽  
Experimental Testing ◽  
Design Procedure ◽  
Time History ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Isolation System ◽  
Sliding Surfaces ◽  
Residual Displacements ◽  
Friction Pendulum

An extensive experimental testing programme named JETBIS project (Joint Experimental Testing of Base Isolation Systems) was developed within the RELUIS II project (Task 2.3.2) and RELUIS III project (Line 6) involving partners from different Italian universities. This paper describes the seismic tests performed by the research unit of University of Basilicata (UNIBAS) on an isolation system based on Double Concave Friction Pendulum (DCFP) bearings. The DCFP bearing contains two separate concave sliding surfaces and exhibits different hysteretic properties at different stages of displacement response. The main objective of this work is to evaluate the horizontal response of the DCFP isolators by means of controlled-displacement tests and shaking table tests. The experimental model was a 1/3 scaled steel framed structure with one storey and one bay in both directions. Four DCFP bearings with equal properties of the sliding surfaces were considered. In this work, three different sliding surface conditions (with and without lubrication) have been studied. The isolated base model was subjected to 8 natural earthquakes of increasing seismic intensities and considering two mass configurations (with both symmetrical and eccentric masses). The reliability of the design procedure considered for the isolation system was verified also when relevant residual displacements occurred due to previous earthquakes. In this paper, the comparisons between the experimental outcomes and the numerical results of nonlinear time-history analyses using SAP2000 are shown.

Inquiry Into Characteristic of Multiple Friction Pendulum System With Multiple Sliding Surfaces Under Bidirectional Loadings

2013 ◽  
Author(s):  
C. S. Tsai ◽  
Y. M. Wang ◽  
H. C. Su
Keyword(s):  
Earthquake Engineering ◽  
Steel Structure ◽  
Shaking Table ◽  
Isolation System ◽  
Pendulum System ◽  
Ground Shaking ◽  
Sliding Surfaces ◽  
Friction Pendulum ◽  
Stiffness And Damping ◽  
Friction Pendulum System

In order to investigate the bidirectional characteristic of a multiple friction pendulum system (MFPS) with multiple sliding surfaces, a series of component tests were performed by using the shaking table in the National Center for Research on Earthquake Engineering, Taipei, Taiwan. The multiple friction pendulum system with multiple sliding surfaces consists of double concave surfaces, more than one intermediate sliding plates and one articulated slider located between the concave surfaces and intermediate sliding plates. These devices can continuously change their horizontal stiffness, damping, and displacement capacities during ground shaking by virtue of the properties such as radii and friction coefficients of multiple sliding surfaces. In this study, both uni- and bidirectional component tests of a multiple friction pendulum system with three and four sliding surfaces were carried out to investigate its mechanical characteristic. Furthermore, results obtained from the shaking table tests of an isolated steel structure demonstrate that the MFPS isolation system with multiple sliding surfaces could properly change its stiffness and damping effect, and effectively reduce the excitation force during ground shaking.

Quintuple Friction Pendulum Isolator: Behavior, Modeling, and Validation

2016 ◽  
Vol 32 (3) ◽  
pp. 1607-1626 ◽  
Author(s):  
Donghun Lee ◽  
Michael C. Constantinou
Keyword(s):  
Computational Model ◽  
Analytical Model ◽  
Adaptive Behavior ◽  
Computational Models ◽  
Behavior Modeling ◽  
Analysis And Design ◽  
Frictional Properties ◽  
Sliding Surfaces ◽  
Multi Stage ◽  
Friction Pendulum

This paper describes the behavior of the quintuple friction pendulum isolator, a spherical sliding isolator with six sliding surfaces, five effective pendula, and nine regimes of operation that allow for complex multi-stage adaptive behavior depending on the amplitude of displacement. An analytical model is presented that is capable of tracing the behavior of the isolator in two general configurations of geometric and frictional properties. This analytical model is useful for verifying computational models and in performing simplified calculations for analysis and design. A computational model that can be implemented in the program SAP2000 is also presented and verified by comparison to the analytical model. A model quintuple friction pendulum isolator has been tested and the results have been used to validate the analytical and computational models.

FINE-TUNING OF MODELLING STRATEGY TO SIMULATE THERMO-MECHANICAL BEHAVIOUR OF DOUBLE FRICTION PENDULUM SEISMIC ISOLATORS UST ESTIMATOR

2019 ◽  
Vol 3 (Special Issue on First SACEE'19) ◽  
pp. 165-172
Author(s):  
Vincenzo Bianco ◽  
Giorgio Monti ◽  
Nicola Pio Belfiore
Keyword(s):  
Multibody Dynamics ◽  
Mechanical Behaviour ◽  
Mechanical Model ◽  
Dynamic Behaviour ◽  
Experimental Testing ◽  
Fine Tuning ◽  
Proposed Model ◽  
Modelling Techniques ◽  
Friction Pendulum

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.

Interaction of tungsten in dry sliding against steel under high density electric current

2019 ◽  
pp. 101-109 ◽  
Author(s):  
M. I. Aleutdinova ◽  
V. V. Fadin ◽  
Yu. P. Mironov
Keyword(s):  
Electrical Contact ◽  
Analysis Data ◽  
Dry Sliding ◽  
Sliding Surface ◽  
X Ray ◽  
Sliding Surfaces ◽  
Quenched Steel ◽  
Sliding Electrical Contact ◽  
A Current ◽  
Tungsten Steel

The possibility of creating a wear-resistant dry sliding electrical contact tungsten/steel was studied. It was shown that tungsten caused severe wear of the quenched steel counterbody due to unlimited plastic flow of its surface layer at a current density up to 150 A/cm2 . This indicated the impossibility of achieving satisfactory characteristics of such a contact. Low electrical conductivity and wear resistance of the contact tungsten/steel were presented in comparison with the known high copper/steel contact characteristics under the same conditions. X-ray phase analysis data of the steel sliding surfaces made it possible to state that the cause of the unsatisfactory sliding of tungsten was the absence of the necessary concentration of FeO oxide on the sliding surface of the steel. 

Robust sliding mode control for a class of underactuated systems with mismatched uncertainties

2009 ◽  
Vol 223 (6) ◽  
pp. 785-795 ◽  
Author(s):  
D W Qian ◽  
X J Liu ◽  
J Q Yi
Keyword(s):  
Robust Control ◽  
Sliding Mode Control ◽  
Control Method ◽  
Sliding Mode ◽  
Underactuated Systems ◽  
Sliding Surface ◽  
Nominal System ◽  
Sliding Surfaces ◽  
Mode Control ◽  
Mismatched Uncertainties

Based on the sliding mode control methodology, this paper presents a robust control strategy for underactuated systems with mismatched uncertainties. The system consists of a nominal system and the mismatched uncertainties. Since the nominal system can be considered to be made up of several subsystems, a hierarchical structure for the sliding surfaces is designed. This is achieved by taking the sliding surface of one of the subsystems as the first-layer sliding surface and using this sliding surface and the sliding surface of another subsystem to construct the second-layer sliding surface. This process continues till the sliding surfaces of all the subsystems are included. A lumped sliding mode compensator is designed at the last-layer sliding surface. The asymptotic stability of all of the layer sliding surfaces and the sliding surface of each subsystem is proven. Simulation results show the validity of this robust control method through stabilization control of a system consisting of two inverted pendulums and mismatched uncertainties.

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