Experimental investigation of the re-centring capability of curved surface sliders

Quaglini, Virginio; Gandelli, Emanuele; Dubini, Paolo

doi:10.1002/stc.1870

Cited by 36 publications

(34 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…CSS = Curved Surface Slider. [24] To examine ground motions with different frequency contents, a number of records was obtained from the Pacific Earthquake Engineering Research Center (PEER) database (http://peer.berkeley.edu/nga) and classified upon the pulse-like feature and the period of maximum spectral velocity of the time history, in accordance with the ranges established in Table 2.…”

Section: Parametric Modelmentioning

confidence: 99%

“…A parametric investigation considering a variety of natural ground motions concluded that CSSs experience negligible residual displacements when d cd /d rm is greater than 2.5 [6] ; the study also demonstrated that the occurrence of pulse-like seismic ground motions is particularly unfavourable for systems with poor restoring capability as it may imply large residual displacements. [6] Shake table tests on base-isolated structures equipped with either triple friction pendulum isolators [23] or single and double curvature sliders, [24] and simulating sequences of low-to-moderate and high-amplitude seismic ground motions, showed that depending on the sequence details, the system may either accumulate or recover residual displacements. Theoretical considerations [14] based on energy conservation concluded that when pulse-like time histories are imposed, an offset displacement d o of the isolation system induces a change Δd cd of the maximum displacement that occurs in the same direction of d o , and at first approximation, it is proportional to (d cd /d rm ) −1 :…”

Section: Introductionmentioning

confidence: 99%

“…On the contrary, when the offset displacement is applied in the negative direction respect to the maximum seismic displacement, the result is a decrease of d cd , as illustrated in Figure 2. [24] The large use of CSSs requires a detailed knowledge of their behaviour. The present study aims at giving more insight into the interaction between nonseismic and seismic movements, investigating the sensitivity of the seismic displacement of a structure isolated with CSSs to an offset displacement.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

“Total displacement of curved surface sliders under nonseismic and seismic actions: A parametric study”

Quaglini

Gandelli

Dubini

et al. 2017

Struct Control Health Monit

Self Cite

View full text Add to dashboard Cite

The re-centring capability is recognized as a fundamental function of any effective isolation system, not only because it is associated to small or negligible deformation at the end of the earthquake but rather because it prevents displacement build up that may limit the capability of the structure to withstand aftershocks and future earthquakes. The current Eurocode recommends to estimate the maximum total displacement of the isolated system as the superposition of the nonseismic offset displacement resulting from permanent actions, long-term deformations and thermal movements of the structure, and of the amplified seismic displacement induced by the design earthquake. For systems endowed with low re-centring capability, the estimation shall also account for the possible accrual of displacements during the lifetime of the structure. However, the aforementioned criteria have never been evaluated for curved surface sliders, which are characterized by an inherent nonlinear behaviour.The study aims at giving more insight into the matter by conducting a parametric study based on one-directional nonlinear response time history analyses and considering a variety of seismic scenarios. The first part of the study investigates the effect of a nonseismic displacement on the earthquake-induced displacement and formulates a criterion to evaluate the capability of curved surface sliders to provide a seismic response independent of the offset displacement. The response of the isolation system to natural sequences of earthquakes, where the offset displacement is the residual displacement from the previous shake, is addressed in the second part of the paper. The provisions of the Eurocode are eventually checked against the observed data.KEYWORDS base isolation, curved surface slider, nonseismic displacement, re-centring capability, total displacement LIST OF NOTATIONS USED IN THE PAPER: d, horizontal displacement of the isolation system; D, horizontal displacement capacity of the isolator in a SDOF system; D i , horizontal displacement capacity of isolator i; d cd , design displacement at the centre of stiffness of the isolation system; d G , non-seismic displacement of the isolator in a SDOF system; d G,i , non-seismic displacement of the isolator i; d m , design seismic displacement of the isolator in a SDOF system; d m,i , design seismic displacement of the i-th isolator; d m,MS , maximum displacement induced by the main shock of a ground motion sequence; d m,o , maximum total displacement under coexisting non-seismic and seismic actions; d o , maximum design non-seismic displacement; d rm , maximum residual displacement; d r , residual displacement of the isolation system with no offset displacement; d r,o , residual displacement of the isolation system affected from the offset displacement d G ; d r,AS , residual displacement at the end of the aftershock of a ground motion sequence; d r,FS , residual displacement at the end of the foreshock of a ground motion sequence; d r,MS , residual displacement at the end of the main s...

show abstract

Section: Parametric Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

“Total displacement of curved surface sliders under nonseismic and seismic actions: A parametric study”

Quaglini

Gandelli

Dubini

et al. 2017

Struct Control Health Monit

Self Cite

View full text Add to dashboard Cite

show abstract

“…Remarkable innovations have been noticed in the last decade for both strategies. Concerning base isolation, single and multiple curved surface sliders [1][2][3][4] and roller-type isolators [5][6][7] became a competitive alternative to the widely used class of high damping rubber bearings. At the same time, new technologies, or improved versions of existing ones, have been implemented in the field of energy dissipation, capable of supplying supplemental damping and horizontal stiffness in different proportions, depending on the mechanical characteristics of dampers and their installation layout.…”

Section: Introductionmentioning

confidence: 99%

Energy-Based Design Criterion of Dissipative Bracing Systems for the Seismic Retrofit of Frame Structures

Terenzi

2018

Applied Sciences

View full text Add to dashboard Cite

Featured Application: An energy-based sizing criterion is proposed to help designing dissipative bracing systems incorporating fluid viscous spring-dampers for the seismic retrofit of frame structures.Abstract: Direct sizing criteria represent useful tools in the design of dissipative bracing systems for the advanced seismic protection of existing frame structures, especially when incorporated dampers feature a markedly non-linear behaviour. An energy-based procedure is proposed herein to this aim, focusing attention on systems including fluid viscous devices. The procedure starts by assuming prefixed reduction factors of the most critical response parameters in current conditions, which are evaluated by means of a conventional elastic finite element analysis. Simple formulas relating the reduction factors to the equivalent viscous damping ratio of the dampers, ξ eq , are proposed. These formulas allow calculating the ξ eq values that guarantee the achievement of the target factors. Finally, the energy dissipation capacity of the devices is deduced from ξ eq , finalizing their sizing process. A detailed description of the procedure is presented in the article, by distinguishing the cases where the prevailing structural deficiencies are represented by poor strength of the constituting members, from the cases having excessive horizontal displacements. A demonstrative application to the retrofit design of a reinforced concrete gym building is then offered to explicate the steps of the sizing criterion in practice, as well as to evaluate the enhancement of the seismic response capacities generated by the installation of the dissipative system.

show abstract

“…Two measured accelerograms are used as ground motion data that are PGA‐scaled over a wide range to resolve accurately the isolation performance as function of PGA. Not topic of this investigation is that the friction coefficient of real CSSs depends on several state variables as, for example, sliding velocity, pressure, and sliding path temperature, and the recentring error is not investigated as function of initial and dry sliding friction but checked according to Eurocode 8…”

Section: Introductionmentioning

confidence: 99%

Curved surface sliders with friction damping, linear viscous damping, bow tie friction damping, and semiactively controlled properties

Weber

Distl

Meier

et al. 2018

Struct Control Health Monit

View full text Add to dashboard Cite

Summary This paper investigates the isolation performance of curved surface sliders (CSSs) with different damping mechanisms. The following passive damping mechanisms are considered: passive friction damping as commonly present in CSSs, linear viscous damping as linear damping mechanism, and bow tie friction as adaptive, that is, position‐dependent, but passive approach; CSSs with adaptive behaviour based on different sliding regimes are not considered. From the field of CSSs with semiactive dampers, two control strategies are considered: amplitude proportional friction damping aiming at linearizing the friction damping over one cycle and semiactively controlled damping and stiffness properties to enhance the decoupling between ground and structure by the emulation of zero dynamic stiffness. The CSSs under consideration are assessed in terms of peak structural acceleration, peak CSS horizontal force and displacement, and recentring error as function of peak ground acceleration (PGA) of the accelerograms. The results demonstrate that (a) friction damping can be optimized at one PGA only due to its nonlinearity, (b) the optimization of linear viscous damping does not depend on PGA, (c) optimized bow tie friction improves the isolation at low PGA while the isolation at medium to high PGAs worsens, (d) optimized amplitude proportional friction damping does not improve the isolation compared with optimized linear viscous damping, and (e) zero dynamic stiffness is preferably emulated only for a certain range of CSS relative motion amplitude to keep the recentring error within acceptable limits.

show abstract

Experimental investigation of the re-centring capability of curved surface sliders

Cited by 36 publications

References 30 publications

“Total displacement of curved surface sliders under nonseismic and seismic actions: A parametric study”

“Total displacement of curved surface sliders under nonseismic and seismic actions: A parametric study”

Energy-Based Design Criterion of Dissipative Bracing Systems for the Seismic Retrofit of Frame Structures

Curved surface sliders with friction damping, linear viscous damping, bow tie friction damping, and semiactively controlled properties

Contact Info

Product

Resources

About