A base isolation system for structures subject to extreme seismic events characterized by anomalous values of intensity and frequency content

Abstract In this paper the seismic response of a multi-storey reinforced concrete (RC) building base isolated by lead rubber bearings (LRBs) is compared with the seismic response of the same structure base isolated by an innovative seismic isolator which we called high damping hybrid seismic isolator (HDHSI). The study is performed in the context of passive structural control and seismic base isolation technique for the earthquake resistance of RC buildings. This novel high damping hybrid seismic isolator (HDHSI) is obtained by the assembly in series of a lead rubber bearing (LRB) and a friction slider (FS) characterized by a high friction coefficient. The base isolation system is realized by elastomeric materials and steel-teflon bearings. The nonlinear behavior of the composite devices is investigated by reporting a detailed analysis of the hysteretic cycles of the isolators. The purpose of the analysis is to highlight the features offered by the proposed HDHSI base isolation system compared to the traditional LRB base isolation system in the seismic protection of structures. Nonlinear dynamic analyses are performed for base isolated multi-storey RC structures. In the analysis the inputs of different seismic events are adopted which can be considered as extreme events in terms of peak ground acceleration and in terms of frequency content. The seismic records are related to seismic events obtained by suitably amplifying the El Centro earthquake. They are characterized by their high values of the peak ground acceleration. Another seismic event considered in the analysis is the Erzincan earthquake which is characterized by high energetic content at low frequencies. Accordingly, the seismic events adopted in the analysis are characterized by anomalous values of intensity and frequency content. A nonlinear dynamic analysis is illustrated for a multi-storey RC building base isolated by the proposed HDHSI system compared with the traditional LRB base isolation system. The time history of the base shear and the time history of the base displacement of the superstructure are illustrated for the different analyzed seismic events. The benefits of the presented composite HDHSI base isolation system are shown to be appropriate in conferring a suitable seismic protection to multi-storey RC buildings even under extreme seismic events.

[1]  R. Taylor,et al.  A nonlinear finite element plasticity formulation without matrix inversions , 2016 .

[2]  Ferdinando Auricchio,et al.  Second-order accurate integration algorithms for von-Mises plasticity with a nonlinear kinematic hardening mechanism , 2007 .

[3]  Donato Cancellara,et al.  A Novel Seismic Base Isolation System Consisting of a Lead Rubber Bearing in Series with a Friction Slider. Part II: Application to a Multi-Storey RC Building and Comparison with Traditional Systems , 2012 .

[4]  Michael C. Constantinou,et al.  Property Modification Factors for Seismic Isolation Bearings , 1999 .

[5]  Andrei M. Reinhorn,et al.  Teflon Bearings in Base Isolation I: Testing , 1990 .

[6]  Donato Cancellara,et al.  A Novel Seismic Base Isolation System Consisting of a Lead Rubber Bearing in Series with a Friction Slider. Part I: Nonlinear Modeling of the System , 2012 .

[7]  Giuseppe Muscolino,et al.  A numerical method for the time‐domain dynamic analysis of buildings equipped with viscoelastic dampers , 2011 .

[8]  Y. K. Wen,et al.  Random vibration of hysteretic systems under bi‐directional ground motions , 1986 .

[9]  Michael C. Constantinou.  NCEER-TAISEI CORPORATION RESEARCH PROGRAM ON SLIDING SEISMIC ISOLATION SYSTEMS FOR BRIDGES EXPERIMENTAL AND ANALYTICAL STUDY OF A FRICTION PENDULUM SYSTEM (FPS). , 1993 .

[10]  Donato Cancellara,et al.  Nonlinear dynamic analysis for multi-storey RC structures with hybrid base isolation systems in presence of bi-directional ground motions , 2016 .

[11]  R. Taylor,et al.  An efficient return mapping algorithm for elastoplasticity with exact closed form solution of the local constitutive problem , 2015 .

[12]  Anil K. Chopra,et al.  Estimation of Seismic Demands on Isolators Based on Nonlinear Analysis , 2004 .

[13]  Farzad Naeim,et al.  Design of seismic isolated structures , 1999 .

[14]  M. Livolant,et al.  Seismic isolation using sliding-elastomer bearing pads , 1985 .

[15]  M. T. Braz-César,et al.  Influence of the location of resistant cores on the seismic response of a reinforced concrete three-dimensional frame equipped with HDRB base isolation devices , 2007 .

[16]  Antonina Pirrotta,et al.  Dynamic Finite Element analysis of fractionally damped structural systems in the time domain , 2015 .

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

[18]  Yeong-Bin Yang,et al.  Response of multi‐degree‐of‐freedom structures with sliding supports , 1990 .

[19]  W. H. Robinson,et al.  A LEAD-RUBBER SHEAR DAMPER , 1977 .

[20]  Y. Wen.  Method for Random Vibration of Hysteretic Systems , 1976 .

[21]  Donato Cancellara,et al.  A New Passive Seismic Control Device for Protection of Structures under Anomalous Seismic Events , 2011 .

[22]  Andrei M. Reinhorn,et al.  Teflon Bearings in Base Isolation II: Modeling , 1990 .

[23]  M. Khodaverdian,et al.  Dynamics of resilient‐friction base isolator (R‐FBI) , 1987 .