SEISMIC ISOLATION OF BRIDGES THROUGH CURVED SURFACE SLIDERS AND VISCOUS DAMPERS

2021 ◽  
Author(s):  
Maria Gabriella Castellano ◽  
Alberto Dusi
Keyword(s):  
Seismic Isolation ◽  
Curved Surface ◽  
Viscous Dampers

Dynamic properties of the isolators used in the Green Museum Library (Taiwan)

2021 ◽  
Author(s):  
Ivan Marenda ◽  
Agostino Marioni ◽  
Roberto Dalpedri ◽  
Marco Banfi
Keyword(s):  
Scale Effect ◽  
Seismic Isolation ◽  
Production Control ◽  
Dynamic Properties ◽  
Friction Material ◽  
Curved Surface ◽  
Natural Period ◽  
Response Data ◽  
Factory Production ◽  
Friction Pendulum

<p>Over the last decades seismic isolation technology has got a foothold in the structural protection increasing both the damping and the natural period of the superstructure. The curved surface sliding isolator is one of the most common devices used to aim at this goal. It features a special friction material (HIM) able to dissipate a very large amount of energy while, the recentring capacity is given by the pendulum effect. This kind of isolator has been used in the Green Museum Palace (Taiwan). The constancy of its behaviour has been investigated in ShakeLab (Italy), testing 100% of the Friction Pendulum devices in factory production control. In this paper, response data from FPC tests on seven types of Friction Pendulum devices are illustrated. These data show the constancy of the performance of the isolators subjected to design conditions. Furthermore, scale effect in dynamic properties has been studied because of different size isolators have been taken into account.</p>

scholarly journals Base Isolation of Buildings with Curved Surface Sliders: Basic Design Criteria and Critical Issues

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Fernando Saitta ◽  
Paolo Clemente ◽  
Giacomo Buffarini ◽  
Giovanni Bongiovanni ◽  
Antonello Salvatori ◽  
...  
Keyword(s):  
Seismic Isolation ◽  
Lower Cost ◽  
Base Isolation ◽  
Static Friction ◽  
Low Energy ◽  
Curved Surface ◽  
Mass Center ◽  
Isolation System ◽  
Critical Issues ◽  
Loss Of Contact

Curved surface sliders are being used more and more in the seismic isolation of buildings. They are preferred not only because of their lower cost with respect to elastomeric isolators but also of their technical characteristics, such as the fact that the value of the period of vibration is independent of the mass and the automatic coincidence between the gravity mass center of the superstructure and the stiffness center of the isolation system. In this paper, these features are analysed with reference to simple structures, pointing out the possibility of rotations of the superstructure and the loss of contact in some devices. Finally, the importance of the static friction is also emphasized showing the experimental seismic response of an isolation system under a low-energy earthquake. For all these reasons, the use of nonlinear analysis, revised and detailed in this paper, is advisable for the isolation system made of curved surface sliders.

DESIGN FORCE TRANSMITTED BY ISOLATION SYSTEM COMPOSED OF LEAD-RUBBER BEARINGS AND VISCOUS DAMPERS

2010 ◽  
Vol 10 (02) ◽  
pp. 287-298 ◽  
Author(s):  
J. S. HWANG ◽  
C. F. HUNG ◽  
Y. N. HUANG ◽  
S. J. WANG
Keyword(s):  
Phase Angle ◽  
Seismic Isolation ◽  
Soft Soil ◽  
Near Field ◽  
Viscous Dampers ◽  
Maximum Displacement ◽  
Isolation System ◽  
Lead Rubber Bearings ◽  
Response History Analysis ◽  
Rubber Bearings

In seismic isolation design of structures located at soft soil sites or near field areas, viscous dampers (VD) are often included as part of the isolation system to minimize its maximum displacement. Due to the 90° phase angle existing between the force and displacement of the VD, the maximum force transmitted by the isolation system cannot be calculated by simply combining the forces of the isolation bearings, such as lead-rubber bearings (LRB) or high damping rubber bearings (HDRB), and VD in association with the design displacement. Conforming to the code-specified equivalent lateral response procedure for isolation design, this paper presents a formula for determining the seismic design force of the combined LRB and VD isolation system, taking into account the phase angle between the combined force of the LRB and VD and the displacement of the isolation system. The numerical results have shown that the maximum responses of the isolation system predicted by the proposed formula are conservative and comparable with those from the inelastic dynamic response history analysis.

scholarly journals Accuracy of Analytical Models to Predict Primary and Secondary System Response in Seismically Isolated Buildings

2021 ◽  
Author(s):  
Cengiz Ipek ◽  
Eric D. Wolff ◽  
Michael C. Constantinou
Keyword(s):  
Seismic Isolation ◽  
Response Spectra ◽  
Analytical Models ◽  
System Response ◽  
Primary System ◽  
Secondary System ◽  
Viscous Dampers ◽  
Floor Response Spectra ◽  
Analytical Results ◽  
Seismically Isolated

Abstract Seismic isolation is generally considered an effective earthquake protection strategy. As application of seismic isolation increases, decisions on the use of one particular isolator versus another isolator increasingly depend on computed responses with complex analytical models. Accordingly, validation of analytical models to predict primary (structural) and secondary system (non-structural component) response in seismically isolated buildings becomes very important. This paper presents comparisons of experimental and analytical results on the primary and secondary system response of a building model in order to provide information on the accuracy of the predicted response. The tested model was configured as a 6-story building at quarter length scale in a moment-frame configuration, and with the following seismic isolation systems: a) Low damping elastomeric bearings with and without linear or nonlinear viscous dampers, b) Single Friction Pendulum (FP) bearings with and without linear or nonlinear viscous dampers, and c) Lead-rubber bearings. Response quantities compared include story drifts and isolator shear forces and displacements for the primary system, and peak floor total velocities and floor response spectra that relate to secondary system response. This paper presents samples results out of a total of 288 comparisons of experimental and analytical results presented in an MCEER report. It is shown that the primary and secondary system response is computed with sufficient accuracy by the analytical models but some response quantities may be underestimated or overestimated by significant amounts.

Preliminary study on the threshold stiffness and residual displacement of the multangular-pyramid concave friction system (MPCFS) for seismic isolation

2021 ◽  
pp. 136943322110093
Author(s):  
Xiong Wei ◽  
Jiang Li-Zhong ◽  
Li Yao-Zhuang
Keyword(s):  
Seismic Isolation ◽  
Central Point ◽  
Curved Surface ◽  
Engineering Practice ◽  
Ambient Vibrations ◽  
Residual Displacement ◽  
Building Model ◽  
Preliminary Study ◽  
Simulation Results ◽  
Storey Building

In this research, the threshold stiffness and residual displacement of the MPCFS are both investigated. The MPCFS has a higher threshold (breakaway) stiffness and no residual displacement after earthquakes or ambient vibrations, which makes it different from the conventional Curved Surface Slider (CSS). These two features can enable the MPCFS to be more stable when experiencing micro-to-small shakings, and always restore to its central point after earthquakes. With the aim of testifying the two features, a series of analytical simulations are conducted on a four-storey building model equipped with MPCFS. The analytical results are compared with that obtained with CSS. The simulation results validate the aforementioned virtues of MPCFS over the CSS. This indicates that MPCFS has great potential in the engineering practice of seismic isolation.

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