Improved numerical analysis for ultimate behavior of elastomeric seismic isolation bearings

Ishii, Kuniyoshi; Kikuchi, Masaru

doi:10.1002/eqe.3123

Cited by 23 publications

(14 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the present study, the Axial SP material, available in OpenSees, was associated with the vertical behavior in tension and compression. The material is completely defined by the following parameters: (i) initial elastic stiffness along vertical direction E init , (ii) post-elastic stiffness in compression (1/2 E init ) and in tension (1/100 E init ), (iii) cavitation stress (f ty = 2 G r [6]) and (iv) yielding stress in compression (f cy = 100 MPa [16]).…”

Section: Numerical Modelingmentioning

confidence: 99%

Identification and Calibration of Advanced Hysteresis Models for Recycled Rubber–Fiber-Reinforced Bearings

2022

View full text Add to dashboard Cite

Several studies have investigated the feasibility of reducing the implementation cost of base isolation. In this optic, recycled rubber–fiber-reinforced bearings (RR–FRBs) represent a suitable solution for structures in developing countries. Such devices can be produced using simple manufacturing procedures at a limited cost with respect to conventional isolators. Full-scale tests on RR–FRBs featured energy dissipation values similar to those associated with high-damping natural rubber bearings (HDRBs). Equivalent viscous damping, ranging from 10 to 15%, resulted from testing of RR–FRBs, with poor degradation after cyclic loading. On the other hand, a sensible softening response, associated with the axial–shear interaction, which is much more significant compared to that exhibited by HDRBs, was observed. As a result, the numerical description of the cyclic behavior of the RR–FRBs appears to be more challenging than that of HDRBs. In past studies, simple bilinear hysteresis models were adopted to describe the cyclic behavior of low-cost rubber bearings, thus completely neglecting the P-delta effects which significantly influence the dynamic behavior of such bearings. In this paper, advanced hysteresis numerical models, able to capture the nonlinear response of RR–FRBs, were examined and properly calibrated using a powerful optimization technique, the differential evolution algorithm. Preliminary results of the numerical analyses, performed in OpenSees, were described and compared with those of experimental tests on low-cost rubber bearings. The findings of this study represent the first step of a characterization procedure aimed to provide an accurate representation of the dynamic behavior of these particular bearings. Obviously, additional studies are needed to compare results of response history analyses with those of experimental tests for real structures on RR–FRBs. In this optic, the present paper, along with further studies, could provide a new impulse for the application of low-cost rubber-based devices in current practice.

show abstract

Section: Numerical Modelingmentioning

confidence: 99%

Identification and Calibration of Advanced Hysteresis Models for Recycled Rubber–Fiber-Reinforced Bearings

2022

View full text Add to dashboard Cite

show abstract

“…All that considered, in the present paper, the mechanical model of the HDRBs has been improved to overcome those limitations. In particular, the Kikuchi bearing element [16] has been adopted in lieu of the HDR bearing model. The Kikuchi bearing element is a two node link element with multi-spring mechanical model which includes two sets of multiple axial springs (one on the top and the other at the bottom of the bearing height) and a set of mid-height multiple (radial) shear springs, all bound together by rigid links.…”

Section: Isolation Systemmentioning

confidence: 99%

Evaluating Collapse Fragility Curves for Existing Buildings Retrofitted Using Seismic Isolation

2020

View full text Add to dashboard Cite

Few studies have investigated so far the collapse capacity of buildings with base-isolation. In such studies, preliminary considerations have been drawn based on a number of assumptions regarding: (i) the methodology used for assessing the collapse capacity, (ii) the collapse conditions and failure modes assumed for both superstructure and isolation system, and (iii) the numerical modeling assumptions. The main results pointed out that the collapse conditions of base-isolated buildings may occur for intensity levels slightly higher than those associated with the design earthquake. In this paper, further developments are made through the use of enhanced models for the description of the behavior of a rubber-based isolation system and the assumption of more rational collapse conditions. Collapse fragility functions, in terms of mean and dispersion values, are proposed for two archetypes representative of existing buildings retrofitted using the seismic isolation technique. The collapse margin ratio (median collapse capacity Sa,C, namely the spectral acceleration associated to a probability of exceedance equal to 50%, divided by the design spectral acceleration at the collapse prevention limit state) has been evaluated for each examined case-study. Values ranging from 1.10 to 1.45 were found.

show abstract

“…In particular, linear springs representing the HDR bearings have been replaced by non-linear elements adopting the HDR isolator (Masaki et al, 2017) available in the Sap 2000 software (Computer and Structures, 1995). This model is bidirectional and accounts for non-linear phenomena, such as the strain-dependent behavior of the HDR bearings, but neglects other aspects, such as the strain hardening at large shear strains (larger than 250%) or the effect of the vertical load on the horizontal response of the bearings (Ishii and Kikuchi, 2018). This may be important for large axial loads close to the buckling capacity of the bearing in the deformed configuration (Kelly, 1997).…”

Section: Non-linear Dynamic Analyses and Seismic Risk Assessmentmentioning

confidence: 99%

A Resilience and Robustness Oriented Design of Base-Isolated Structures: The New Camerino University Research Center

Dall’Asta

Leoni

Micozzi

et al. 2020

Front. Built Environ.

View full text Add to dashboard Cite

This paper analyses the new Research Centre designed for the University of Camerino and entirely financed by the national Civil Protection Department (DPC), following the seismic events in Central Italy in 2016. The building has been designed to guarantee speed of execution as well as a high level of safety, especially regarding seismic actions. The structural solution was to create an isolated system with a steel braced superstructure with pinned joints and r.c. sub-structures able to adapt to the complex morphology of the area. As described in the first part of the paper, design choices have been made to achieve a high level of resilience and robustness, i.e., to limit damage to structural and non-structural components and equipment under moderate and design seismic actions and to avoid disproportionate consequences in the event of extreme actions, larger than the design ones. In the second part of the paper, specific risk analyses have been carried out to evaluate the real performance of the building under increasing intensity levels, with reference to both serviceability and ultimate conditions. To this purpose a site-specific hazard study was first conducted, then non-linear analyses were performed using a hazard-consistent set of records with return periods ranging from T R = 60 years to T R = 10000 years. The main demand parameters of both the isolation system and the superstructure were recorded and capacity values corresponding to different ultimate and damage limit conditions were defined. The results obtained in terms of demand hazard curves show that the building performances in terms of robustness and resilience are very high, confirming the efficacy of the strategies adopted in the design.

show abstract

Improved numerical analysis for ultimate behavior of elastomeric seismic isolation bearings

Cited by 23 publications

References 18 publications

Identification and Calibration of Advanced Hysteresis Models for Recycled Rubber–Fiber-Reinforced Bearings

Identification and Calibration of Advanced Hysteresis Models for Recycled Rubber–Fiber-Reinforced Bearings

Evaluating Collapse Fragility Curves for Existing Buildings Retrofitted Using Seismic Isolation

A Resilience and Robustness Oriented Design of Base-Isolated Structures: The New Camerino University Research Center

Contact Info

Product

Resources

About