Development of adaptive seismic isolators for ultimate seismic protection of civil structures

Base isolation is the most popular seismic protection technique for civil engineering structures. However, research has revealed that the traditional base isolation system due to its passive nature is vulnerable to two kinds of earthquakes, i.e. the near-fault and far-fault earthquakes. A great deal of effort has been dedicated to improve the performance of the traditional base isolation system for these two types of earthquakes. This paper presents a recent research breakthrough on the development of a novel adaptive seismic isolation system as the quest for ultimate protection for civil structures, utilizing the field-dependent property of the magnetorheological elastomer (MRE). A novel adaptive seismic isolator was developed as the key element to form smart seismic isolation system. The novel isolator contains unique laminated structure of steel and MR elastomer layers, which enable its large-scale civil engineering applications, and a solenoid to provide sufficient and uniform magnetic field for energizing the field-dependent property of MR elastomers. With the controllable shear modulus/damping of the MR elastomer, the developed adaptive seismic isolator possesses a controllable lateral stiffness while maintaining adequate vertical loading capacity. In this paper, a comprehensive review on the development of the adaptive seismic isolator is present including designs, analysis and testing of two prototypical adaptive seismic isolators utilizing two different MRE materials. Experimental results show that the first prototypical MRE seismic isolator can provide stiffness increase up to 37.49%, while the second prototypical MRE seismic isolator provides amazing increase of lateral stiffness up to1630%. Such range of increase of the controllable stiffness of the seismic isolator makes it highly practical for developing new adaptive base isolation system utilizing either semi-active or smart passive controls.

[1]  Erik A. Johnson,et al.  "SMART" BASE ISOLATION SYSTEMS , 2000 .

[2]  Anil K. Agrawal,et al.  Semi-active hybrid control systems for nonlinear buildings against near-field earthquakes , 2002 .

[3]  J. A. Abdalla,et al.  VIBRATION CHARACTERISTICS OF A FAR FIELD EARTHQUAKE AND ITS SHAKING EFFECTS ON DUBAI EMERGING SKYSCRAPERS , 2008 .

[4]  James M. Kelly,et al.  Seismic Isolation Systems for Developing Countries , 2002 .

[5]  Farzad Naeim,et al.  Design of seismic isolated structures : from theory to practice , 1999 .

[6]  Billie F. Spencer,et al.  “Smart” Base Isolation Strategies Employing Magnetorheological Dampers , 2002 .

[7]  R. S. Jangid,et al.  Base isolation for near‐fault motions , 2001 .

[8]  Fabio Mazza,et al.  Effects of near‐fault ground motions on the nonlinear dynamic response of base‐isolated r.c. framed buildings , 2012 .

[9]  Eric M. Lui.  Seismic Isolation for Earthquake Resistant Structures , 2001 .

[10]  Tomi Lindroos,et al.  Dynamic compression testing of a tunable spring element consisting of a magnetorheological elastomer , 2007 .

[11]  Bijan Samali,et al.  Development and characterization of a magnetorheological elastomer based adaptive seismic isolator , 2013, Smart Materials and Structures.

[12]  Troy Alexander Morgan.  The use of innovative base isolation systems to achieve complex seismic performance objectives , 2007 .

[13]  B. F. Spencer,et al.  STATE OF THE ART OF STRUCTURAL CONTROL , 2003 .

[14]  J. Gough,et al.  High damping natural rubber seismic isolators , 1997 .

[15]  N. Wongprasert,et al.  Experimental Evaluation of Adaptive Elastomeric Base-Isolated Structures Using Variable-Orifice Fluid Dampers , 2005 .

[16]  Chin-Hsiung Loh,et al.  Hybrid base-isolation with magnetorheological damper and fuzzy control , 2007 .

[17]  Matthias Kröger,et al.  MRE Properties under Shear and Squeeze Modes and Applications , 2010 .

[18]  Ging Long Lin,et al.  Fuzzy Friction Controllers For Semi-active Seismic Isolation Systems , 2009 .

[19]  Chin-Hsiung Loh,et al.  Neuro-fuzzy model of hybrid semi-active base isolation system with FPS bearings and an MR damper , 2006 .

[20]  William Robinson,et al.  Lead‐rubber hysteretic bearings suitable for protecting structures during earthquakes , 1982 .

[21]  E. Kontou,et al.  Modeling of nonlinear viscoelasticity at large deformations , 2008 .

[22]  Mary C. Boyce,et al.  Large strain time-dependent behavior of filled elastomers , 2000 .

[23]  Satish Nagarajaiah.  Structural control benchmark problem: smart base isolated building subjected to near fault earthquakes , 2006 .

[24]  A. Chopra,et al.  Comparing response of SDF systems to near‐fault and far‐fault earthquake motions in the context of spectral regions , 2001 .

[25]  Weihua Li,et al.  Viscoelastic properties of MR elastomers under harmonic loading , 2010 .

[26]  James M. Kelly,et al.  Base Isolation: Linear Theory and Design , 1990 .

[27]  Peng Pan,et al.  BASE-ISOLATION DESIGN PRACTICE IN JAPAN: INTRODUCTION TO THE POST-KOBE APPROACH , 2005 .