Design charts for eurocode-based design of elastomeric seismic isolation systems

Losanno, Daniele; Hadad, Houman Akbari; Serino, Giorgio

doi:10.1016/j.soildyn.2017.12.017

Cited by 27 publications

(10 citation statements)

References 10 publications

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“…Differently, in case of RU-FREIs, the relatively large shear modulus of the rubber and the limited shear strain (γ=50%), resulted in a slender geometry with an aspect ratio close to 1. Consequently, the use of softer compound with higher deformation capacity allows to design more squat geometry thus preventing instability issues [26]. Lateral stability will be investigated up to complete roll-over of the vertical faces under shear tests.…”

Section: Preliminary Design Of Isolatorsmentioning

confidence: 99%

Laboratory Characterization of a Reclaimed Rubber Compound for Low-Cost Elastomeric Isolators

Cilento¹,

Losanno²,

Piga³

2021

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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Although seismic isolation devices are effective in protecting structures during an earthquake, they are generally large, heavy, and expensive, making their application prohibitive for housing buildings. In the last few years, different strategies have been investigated to make seismic isolators cheaper and lighter for housing buildings in developing countries. Lower costs can be obtained at different scales: simplifying the installation process of devices, reducing energy consumption during manufacturing, and using recycled materials. Both weight and cost of isolators could be reduced by adopting flexible reinforcements in place of steel reinforcing plates, also allowing easier installation without bolted connections in unbounded configuration. Costs can be further reduced by replacing natural rubber with a recycled elastomer. It has been demonstrated that trying to give a second life to rubber is challenging, since devulcanization process, capable of breaking chemical bonds between rubber and sulphur, is highly polluting and requires high consumption of energy. In the present work, a recycled compound has been preliminary developed with mechanical properties not significantly lower than virgin rubber. Obtained parameters are satisfactory for use in unbounded isolators with flexible internal reinforcement where internal stresses are significantly reduced. In particular, a novel compound has been properly formulated in order to be lower cost in comparison to traditional one. Mechanical characterization of the material showed excellent properties including shear modulus and hardness similar to those of a soft rubber, even if a reduced ultimate deformation capacity is achieved. Furthermore, rubber adhesion with different fabrics has been investigated. Preliminary results are very promising and pave the way for the development of high-performance and low-cost rubber isolators.

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Section: Preliminary Design Of Isolatorsmentioning

confidence: 99%

Laboratory Characterization of a Reclaimed Rubber Compound for Low-Cost Elastomeric Isolators

Cilento¹,

Losanno²,

Piga³

2021

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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“…The obtained value for unit total mass is Ais=0.00086 m 2 . The diameter of HDNR bearings is defined based on the effective mass to be isolated according to stability criteria and limits on compressive stresses provided by the codes, as illustrated in [34] for the Eurocode. In addition, the number of elastomeric bearings may be lower than the number of columns of the superstructure following as a result of the use of flat sliders (hybrid isolation system) to increase the range of reachable isolation periods.…”

Section: Design Of the Isolation System And Equivalent Linear Modelmentioning

confidence: 99%

Behaviour of Structures Isolated by HDNR Bearings at Design and Service Conditions

Ragni

Micozzi

Tubaldi

et al. 2020

Journal of Earthquake Engineering

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High Damping Natural Rubber (HDNR) bearings are widely employed for seismic isolation. These bearings are characterized by a remarkable nonlinear behaviour and often by a degrading cyclic response, induced by the addition of filler to enhance its dissipation capacity. This latter phenomenon, denoted as stress-softening or Mullins effect, can significantly influence the nonlinear dynamic response of isolated structures leading to a variability of the seismic response of isolated buildings. Moreover, the behaviour of HDNR bearings may produce an amplification of response, due to higher modes contribution, which can affect the performance of non-structural components and equipment. Models providing an accurate description of the nonlinear behaviour of HDNR bearings with significant stress-softening have been proposed only recently. Thus, the studies in the literature are generally based on simplified models. In this paper, an advanced HDNR model, accounting for variation of stiffness and damping with the strain amplitude and deformation history, is used to analyse the seismic performance of isolated structures at different intensity levels. First, a parametric analysis is carried out on a two-degree of freedom system to study different configurations of practical interest. Subsequently, a multi-degree of freedom system representing a realistic building is analysed to evaluate the response at different floors andthe contribution of higher modes of vibration. The influence of practical aspects, such as the superstructure damping and the friction of the sliders, is also investigated.

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“…To counteract the effect of the earthquake, there are two widely accepted and implemented alternatives. The first consists in isolating the structure at the base, thus reducing the energy input of the earthquake to the building [1][2][3]. While the second one concentrates in mitigating, through auxiliary devices, the energy that has been transmitted by the earthquake to the structure [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Real-Time Hybrid Simulation of a Structure With Circular Fiber Reinforced Isolators

Riascos¹,

Klopov²,

Marulanda³

et al. 2021

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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More than 87% of the Colombian population lives in zones of intermediate and high seismic hazard, which has generated an increasing interest toward base isolated structures. Nowadays, this technique has been mainly applied to hospitals and bridges. However, it is necessary to expand the action field of isolators to diverse kind of structures in countries with high seismic hazard. In this direction, the performance of circular unbounded fiber reinforced elastomeric isolators (U-FREI) was studied in a two degrees-of-freedom (DoF), medium scale structure, under seismic excitation. This evaluation was achieved employing a Real-Time Hybrid Simulation (RTHS), which is defined as a modern cyber-physical technique used for the experimental evaluation of complex systems, that treats the system components with predictable behavior as a numerical substructure, and the components that are difficult to model as an experimental substructure. In this case, the main structure was considered as the numerical substructure and a couple of U-FREI was treated as the experimental substructure. The RTHS was evaluated using a set of Current Assessment Measurements, where an accurate tracking of the transfer system was determined. Furthermore, the experimental results were compared with Shaking Table Tests (STT) developed at University of Naples Federico II. Particularly, peak and RMS comparison of force and acceleration signals showed a similar behavior of the RTHS according to the STT results. Overall, both approaches demonstrated that the U-FREI were able to reduce more than the 70% of the structural drift with respect to the fixed structure, and the applied RTHS methodology was verified.

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Design charts for eurocode-based design of elastomeric seismic isolation systems

Cited by 27 publications

References 10 publications

Laboratory Characterization of a Reclaimed Rubber Compound for Low-Cost Elastomeric Isolators

Laboratory Characterization of a Reclaimed Rubber Compound for Low-Cost Elastomeric Isolators

Behaviour of Structures Isolated by HDNR Bearings at Design and Service Conditions

Real-Time Hybrid Simulation of a Structure With Circular Fiber Reinforced Isolators

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