A cross-program activity focuses on the establishment of an effective experimental and analytical... more A cross-program activity focuses on the establishment of an effective experimental and analytical network to facilitate the exchange of information between researchers located in various institutions across the country. These are complemented by, and integrated with, other MCEER activities in education, outreach, technology transfer, and industry partnerships. This combined experimental and analytical study provides an assessment of the validity and accuracy of analysis methods commonly used for seismically isolated structures, emphasizing secondary system response, contemporary seismic isolation systems, and strong and/or near-fault seismic excitation. A six-story steel model was used in three configurations: flexible moment-frame, asymmetrically braced-frame and stiff braced-frame. Eight isolation systems were studied, namely, low damping elastomeric bearings with and without linear and nonlinear viscous dampers, Friction Pendulum (FP) bearings with and without linear and nonlinear viscous dampers, low damping elastomeric bearings with lead cores, and low damping elastomeric bearings in conjunction with flat sliding bearings. Over 300 experiments were conducted. The various experimental results were compared with analytical results obtained using the SAP2000 and 3D-BASIS-ME computer programs. The vast database of experimental results on secondary system response provided the opportunity to assess the performance of various seismic isolation systems.
ABSTRACT Design standards for seismic isolation of nuclear power plants in USA will consider the ... more ABSTRACT Design standards for seismic isolation of nuclear power plants in USA will consider the effects of beyond design basis loadings, including extreme earthquakes. Seismic isolation is being considered for new build nuclear power plant construction and design of isolation systems will have to consider these extreme loadings, which includes the possibility of net tensile force in bearings under beyond design basis shaking. A series of experiments were conducted at University at Buffalo to characterize the behavior of elastomeric bearings in tension. Sixteen low damping rubber bearings from two manufacturers, with similar geometric properties but different shear moduli, were tested under various loading conditions to determine factors that affect cavitation in an elastomeric bearing. The effect of cavitation on the shear and axial properties of elastomeric bearings was investigated by performing post-cavitation tests. The test data were used to validate a phenomenological model of an elastomeric bearing in tension, which is implemented in OpenSees, ABAQUS and LS-DYNA.
Passive and Active Structural Vibration Control in Civil Engineering, 1994
Sliding seismic isolation systems may consist of a variety of components, of which the most impor... more Sliding seismic isolation systems may consist of a variety of components, of which the most important one is the sliding bearing. Typically, sliding bearings consist of interfaces made of PTFE or PTFE-based composites and highly polished stainless steel. The properties of these interfaces are described.
<p><strong>Title:</strong> Development of Next Generation Adaptive Seismic Prot... more <p><strong>Title:</strong> Development of Next Generation Adaptive Seismic Protection Systems (NEES-2008-0653)</p> <p><strong>Year Of Curation: </strong>2014</p> <p><strong>Description: </strong>Design of conventional structures specified by the codes is based on the philosophy that the structure should withstand seismic loads while sustaining an acceptable level of damage. Structures are designed to prevent collapse but their serviceability and functionality in the aftermath of strong earthquake ground motion are not taken into consideration. This is achieved by designing structures to be ductile and letting them yield when subjected to strong earthquake ground motions. Yielding leads to stiffness and strength degradation, increased interstory drifts, and damage with permanent drifts, which render the structure non-functional.</p> <p><strong>Award: </strong>http://www.nsf.gov/awardsearch/showAward?AWD_ID=0830391</p> <p><strong>PIs & CoPIs: </strong>Satish Nagarajaiah, Michael Constantinou, Andrei Reinhorn, Michael Symans, Douglas Taylor, Jian Zhang</p> <p><strong>Dates: </strong>September 01, 2008 - August 31, 2013</p> <p><strong>Organizations: </strong>Rensselaer Polytechnic Institute, Troy, NY, United States, Rice University, TX, United States, State University of New York at Buffalo, NY, United States, University of California, Los Angeles, CA, United States</p> <p><strong>Facilities: </strong>State University of New York at Buffalo, NY, United States</p> <p><strong>Sponsor: </strong>NSF - CMMI - 0830391</p> <p><strong>Keywords: </strong>Adaptive seismic protection systems, Negative Stiffness Device, Shake table testing, Apparent Weakening, Apparent yielding, base isolated building, Adaptive Stiffness Structures</p> <p><strong>Publications:Â < [...]
The Giant Magellan Telescope (GMT) is an Extremely Large Telescope (ELT) class observatory set to... more The Giant Magellan Telescope (GMT) is an Extremely Large Telescope (ELT) class observatory set to make history as one of the largest telescopes ever built. Vast improvements in the fields of optics, control systems, and mirror fabrication technologies have facilitated correspondingly drastic increases in the size and presence of ground-based telescopes previously thought to be impossible. Size for these observatories has increased to the point where conventional approaches impart seismic demands on the telescope structure and optics that are unmanageable. With this, a refined approach involving base isolation is being designed to provide seismic protection of a sensitive, invaluable instrument that will revolutionize our understanding of the universe.
This study investigates the effect of displacement restraint on the collapse performance of seism... more This study investigates the effect of displacement restraint on the collapse performance of seismically isolated buildings. The displacement restraints considered are stiffening triple Friction Pendulum (FP) bearings and moat walls. The study is based on 6-story perimeter frame seismically isolated buildings designed with special concentrically braced frames (SCBF) and special moment resisting frames (SMF) for a location in California using the minimum criteria of ASCE/SEI 7-10 and ASCE/SEI 7-16 and also using enhanced designs. Results from pushover analysis and nonlinear response history analysis demonstrate that proper designs require a balance between the value of R I for the design of the superstructure and the displacement capacity of the isolators. The paper shows that isolation systems with sufficient displacement capacity before engaging the displacement restraint and a R I factor consistent to that displacement capacity may have an acceptable collapse risk. Values of the design parameters for the superstructure and the displacement capacity and behavior of the isolation system for achieving acceptable collapse risk are presented.
This article presents an analytical study of the seismic collapse performance of seismically isol... more This article presents an analytical study of the seismic collapse performance of seismically isolated buildings and comparable non-isolated buildings. The study is based on archetypical 6-story perimeter frame seismically isolated buildings designed with special concentrically braced frames (SCBF), ordinary concentrically braced frames (OCBF) and special moment resisting frames (SMF) for a location in California using the minimum criteria of ASCE/SEI 7-10 and ASCE/SEI 7-16 and also using a number of enhanced designs. The isolation system consists of triple Friction Pendulum (FP) isolators with stiffening behavior at large displacement. Additionally, double concave sliding isolators are considered and designed per minimum criteria of ASCE/SEI 7 and without a displacement restrainer, a practice permitted by the standards. Non-isolated structures, also with braced and moment frame configurations, are designed using the minimum criteria of ASCE/SEI 7 and studied. The study concludes that seismically isolated buildings designed by the minimum criteria of ASCE/SEI 7 of either 2010 or 2016 may have unacceptable probability of collapse in the Risk-Targeted Maximum Considered Earthquake (MCE R). The probability of collapse in the MCE R becomes acceptable when they are designed with enhanced criteria of R I =1.0 and with isolators having a displacement capacity at initiation of stiffening equal to 1.5 times the demand in the MCE R. It is also observed that designs that meet the minimum criteria of ASCE/SEI 7 of either 2010 or 2016 and without any displacement restrainer have unacceptably high probabilities of collapse.
ABSTRACT The evolutionary stochastic response of a rigid structure resting on a frictionat founda... more ABSTRACT The evolutionary stochastic response of a rigid structure resting on a frictionat foundation and excited by filtered random excitation is studied analytically and by Monte Carlo simulation. Good conelation is observed between analytical and simulation results. The response depends on parameters of the filter only for small to moderate times, while for large times it becomes identical to the response caused by excitation with a white random process. Furthermore, some statistics of the extreme response are obtained. Results presented herein may find application in base isolation of structures,
International Journal of Soil Dynamics and Earthquake Engineering, 1985
This work investigated the control of chaotic behavior of a harmonically perturbed Duffing Oscill... more This work investigated the control of chaotic behavior of a harmonically perturbed Duffing Oscillator using vibration absorber. The systems of t wo degrees of freedom governing equations were simu lated nu mer ically using classical fourth order Runge-Kutta algorith m for a constant time step. The solution time history, phase plots and Poincare maps were used to validate the simu lation. Essentially, the details of the Poincare map were used numerically to determine the periodicity of Duffing oscillator for spectrum of mass ratio at a constant step of 0.001. The time h istory, phase plots and the Poincare at mass ratio (µ), absorber parameters (α a), and amp litude of excitation (F o) are in agreement with what is obtained in open literature. The chaotic response of the Duffing-Absorber system at α a = 1.1, F o = 0.21; and, taken respectively, the Duffing and the absorber initial conditions to be (1.0, 0.0) and (0.0, 0.0), this chaotic response was rendered periodic for some selected mass ratio (0≤µ≤1.0). Specifically, periods 1, 2 and 4 were obtained at µ= 0.208; these periodic responses were obtained at respective values of α a =1.1, α a =1.7803 and α a = 1.7595. In this work, eighty percent of the mass ratio selected did ensure that the chaotic behaviour of the Duffing-Absorber system is rendered periodic. Th is work demonstrated the practical utility of vibrat ion absorber as a chaotic oscillations control tool by the mass ratio approach; and having a recorded succes s of about eighty percent.
AbstractThe open-space damping system has been developed to preserve open space within the frame ... more AbstractThe open-space damping system has been developed to preserve open space within the frame of its installation. An earlier paper by the authors described its function, presented a theory to d...
CISM International Centre for Mechanical Sciences, 1994
Much progress has also been made in research and development of passive energy dissipation device... more Much progress has also been made in research and development of passive energy dissipation devices for structural applications. Similar to seismic isolation technology, the basic role of passive energy dissipation devices when incorporated into a structure is to absorb or consume a portion of the input energy, thereby reducing energy dissipation demand on primary structural members and minimizing possible structural damage. Unlike seismic isolation, however, these devices can be effective against wind excited motions as well as those due to earthquakes. In recent years, serious efforts have been undertaken to develop the concept of energy dissipation or supplemental damping into a workable technology, and a number of these devices have been installed in structures throughout the world. Active control research has a more recent origin. Active structural control is an area of structural protection in which the motion of a structure is controlled or modified by means of the action of a control system through some external energy supply. Considerable attention has been paid to active structural control research in recent years. It is now at the stage where actual systems have been designed,fabricated and installed in full-scale structures. This collection of lecture notes represents an attempt to introduce the basic concepts of these relatively new technologies, to provide a working knowledge of this exciting and fast expanding field, and to bring up-to-date current research and worldwide development in seismic isolation, passive energy dissipation, and active control. The book is divided into three parts, each addressing one of these topics. In each case, basic principles are introduced, followed by design and applications, implementation issues, case studies, and code issues if applicable.
Data recorded from dense seismic arrays such as the Large Scale Seismic Testing array in Lotung, ... more Data recorded from dense seismic arrays such as the Large Scale Seismic Testing array in Lotung, Taiwan, are used for multiple purposes, including development of attenuation and coherency functions, computing dynamic strains in soil, and estimating rotational components of ground motion. The required footprint of a seismic array deployed to compute rotational components of ground motion is a function of the method used for the computations and site specific characteristics, including the apparent seismic wave velocity and the frequency content of expected ground motions. A design procedure for a general two-dimensional seismic array is presented together with a site-specific example using the Surface Distribution Method to extract the rotational components of ground motion. A sensitivity study is performed to determine how the location of recording stations of translational motion in a dense array affects the computed rotational components of earthquake ground motion.
AbstractSeismic energy dissipation systems are typically installed in buildings within diagonal o... more AbstractSeismic energy dissipation systems are typically installed in buildings within diagonal or chevron bracing to improve the seismic performance by reducing drift, and under certain conditions...
Passive energy dissipation systems were developed in the United Stated either specifically for ci... more Passive energy dissipation systems were developed in the United Stated either specifically for civil engineering applications or they evolved from devices and materials used in industrial, automotive, military and aerospace applications. Yielding steel and frictional devices were specifically developed for structural applications, whereas viscoelastic dampers and fluid viscous devices were developed for other applications and adapted for structural applications.
The design of sliding isolation systems and relevant applications are presented. Sliding isolatio... more The design of sliding isolation systems and relevant applications are presented. Sliding isolation systems which found application are: (1) EDF system consisting of leaded bronze-stainless steel sliding bearings without restoring force, (2) TASS system consisting of PTFE-elastomeric sliding bearings and rubber restoring force devices, (3) Spherical sliding or Friction Pendulum System (FPS), (4) Lubricated PTFE sliding bearings with additional energy dissipating devices, and (5) Sliding bearings with restoring force devices for bridge applications.
This section describes the development and application of seismic (or base) isolation in the Unit... more This section describes the development and application of seismic (or base) isolation in the United States. Significant strides have been made in the implementation of the technology. This is attributed to recent advances in seismic isolation hardware and the removal of a number of impediments, which delayed widespread implementation in the near past.
Seismic isolation (also often referred to as base isolation) is a technique for mitigating the ef... more Seismic isolation (also often referred to as base isolation) is a technique for mitigating the effects of earthquakes on structures through the introduction of flexibility and energy absorption capability. Various practical means for introducing this desired flexibility and energy absorption capability are described.
A cross-program activity focuses on the establishment of an effective experimental and analytical... more A cross-program activity focuses on the establishment of an effective experimental and analytical network to facilitate the exchange of information between researchers located in various institutions across the country. These are complemented by, and integrated with, other MCEER activities in education, outreach, technology transfer, and industry partnerships. This combined experimental and analytical study provides an assessment of the validity and accuracy of analysis methods commonly used for seismically isolated structures, emphasizing secondary system response, contemporary seismic isolation systems, and strong and/or near-fault seismic excitation. A six-story steel model was used in three configurations: flexible moment-frame, asymmetrically braced-frame and stiff braced-frame. Eight isolation systems were studied, namely, low damping elastomeric bearings with and without linear and nonlinear viscous dampers, Friction Pendulum (FP) bearings with and without linear and nonlinear viscous dampers, low damping elastomeric bearings with lead cores, and low damping elastomeric bearings in conjunction with flat sliding bearings. Over 300 experiments were conducted. The various experimental results were compared with analytical results obtained using the SAP2000 and 3D-BASIS-ME computer programs. The vast database of experimental results on secondary system response provided the opportunity to assess the performance of various seismic isolation systems.
ABSTRACT Design standards for seismic isolation of nuclear power plants in USA will consider the ... more ABSTRACT Design standards for seismic isolation of nuclear power plants in USA will consider the effects of beyond design basis loadings, including extreme earthquakes. Seismic isolation is being considered for new build nuclear power plant construction and design of isolation systems will have to consider these extreme loadings, which includes the possibility of net tensile force in bearings under beyond design basis shaking. A series of experiments were conducted at University at Buffalo to characterize the behavior of elastomeric bearings in tension. Sixteen low damping rubber bearings from two manufacturers, with similar geometric properties but different shear moduli, were tested under various loading conditions to determine factors that affect cavitation in an elastomeric bearing. The effect of cavitation on the shear and axial properties of elastomeric bearings was investigated by performing post-cavitation tests. The test data were used to validate a phenomenological model of an elastomeric bearing in tension, which is implemented in OpenSees, ABAQUS and LS-DYNA.
Passive and Active Structural Vibration Control in Civil Engineering, 1994
Sliding seismic isolation systems may consist of a variety of components, of which the most impor... more Sliding seismic isolation systems may consist of a variety of components, of which the most important one is the sliding bearing. Typically, sliding bearings consist of interfaces made of PTFE or PTFE-based composites and highly polished stainless steel. The properties of these interfaces are described.
<p><strong>Title:</strong> Development of Next Generation Adaptive Seismic Prot... more <p><strong>Title:</strong> Development of Next Generation Adaptive Seismic Protection Systems (NEES-2008-0653)</p> <p><strong>Year Of Curation: </strong>2014</p> <p><strong>Description: </strong>Design of conventional structures specified by the codes is based on the philosophy that the structure should withstand seismic loads while sustaining an acceptable level of damage. Structures are designed to prevent collapse but their serviceability and functionality in the aftermath of strong earthquake ground motion are not taken into consideration. This is achieved by designing structures to be ductile and letting them yield when subjected to strong earthquake ground motions. Yielding leads to stiffness and strength degradation, increased interstory drifts, and damage with permanent drifts, which render the structure non-functional.</p> <p><strong>Award: </strong>http://www.nsf.gov/awardsearch/showAward?AWD_ID=0830391</p> <p><strong>PIs & CoPIs: </strong>Satish Nagarajaiah, Michael Constantinou, Andrei Reinhorn, Michael Symans, Douglas Taylor, Jian Zhang</p> <p><strong>Dates: </strong>September 01, 2008 - August 31, 2013</p> <p><strong>Organizations: </strong>Rensselaer Polytechnic Institute, Troy, NY, United States, Rice University, TX, United States, State University of New York at Buffalo, NY, United States, University of California, Los Angeles, CA, United States</p> <p><strong>Facilities: </strong>State University of New York at Buffalo, NY, United States</p> <p><strong>Sponsor: </strong>NSF - CMMI - 0830391</p> <p><strong>Keywords: </strong>Adaptive seismic protection systems, Negative Stiffness Device, Shake table testing, Apparent Weakening, Apparent yielding, base isolated building, Adaptive Stiffness Structures</p> <p><strong>Publications:Â < [...]
The Giant Magellan Telescope (GMT) is an Extremely Large Telescope (ELT) class observatory set to... more The Giant Magellan Telescope (GMT) is an Extremely Large Telescope (ELT) class observatory set to make history as one of the largest telescopes ever built. Vast improvements in the fields of optics, control systems, and mirror fabrication technologies have facilitated correspondingly drastic increases in the size and presence of ground-based telescopes previously thought to be impossible. Size for these observatories has increased to the point where conventional approaches impart seismic demands on the telescope structure and optics that are unmanageable. With this, a refined approach involving base isolation is being designed to provide seismic protection of a sensitive, invaluable instrument that will revolutionize our understanding of the universe.
This study investigates the effect of displacement restraint on the collapse performance of seism... more This study investigates the effect of displacement restraint on the collapse performance of seismically isolated buildings. The displacement restraints considered are stiffening triple Friction Pendulum (FP) bearings and moat walls. The study is based on 6-story perimeter frame seismically isolated buildings designed with special concentrically braced frames (SCBF) and special moment resisting frames (SMF) for a location in California using the minimum criteria of ASCE/SEI 7-10 and ASCE/SEI 7-16 and also using enhanced designs. Results from pushover analysis and nonlinear response history analysis demonstrate that proper designs require a balance between the value of R I for the design of the superstructure and the displacement capacity of the isolators. The paper shows that isolation systems with sufficient displacement capacity before engaging the displacement restraint and a R I factor consistent to that displacement capacity may have an acceptable collapse risk. Values of the design parameters for the superstructure and the displacement capacity and behavior of the isolation system for achieving acceptable collapse risk are presented.
This article presents an analytical study of the seismic collapse performance of seismically isol... more This article presents an analytical study of the seismic collapse performance of seismically isolated buildings and comparable non-isolated buildings. The study is based on archetypical 6-story perimeter frame seismically isolated buildings designed with special concentrically braced frames (SCBF), ordinary concentrically braced frames (OCBF) and special moment resisting frames (SMF) for a location in California using the minimum criteria of ASCE/SEI 7-10 and ASCE/SEI 7-16 and also using a number of enhanced designs. The isolation system consists of triple Friction Pendulum (FP) isolators with stiffening behavior at large displacement. Additionally, double concave sliding isolators are considered and designed per minimum criteria of ASCE/SEI 7 and without a displacement restrainer, a practice permitted by the standards. Non-isolated structures, also with braced and moment frame configurations, are designed using the minimum criteria of ASCE/SEI 7 and studied. The study concludes that seismically isolated buildings designed by the minimum criteria of ASCE/SEI 7 of either 2010 or 2016 may have unacceptable probability of collapse in the Risk-Targeted Maximum Considered Earthquake (MCE R). The probability of collapse in the MCE R becomes acceptable when they are designed with enhanced criteria of R I =1.0 and with isolators having a displacement capacity at initiation of stiffening equal to 1.5 times the demand in the MCE R. It is also observed that designs that meet the minimum criteria of ASCE/SEI 7 of either 2010 or 2016 and without any displacement restrainer have unacceptably high probabilities of collapse.
ABSTRACT The evolutionary stochastic response of a rigid structure resting on a frictionat founda... more ABSTRACT The evolutionary stochastic response of a rigid structure resting on a frictionat foundation and excited by filtered random excitation is studied analytically and by Monte Carlo simulation. Good conelation is observed between analytical and simulation results. The response depends on parameters of the filter only for small to moderate times, while for large times it becomes identical to the response caused by excitation with a white random process. Furthermore, some statistics of the extreme response are obtained. Results presented herein may find application in base isolation of structures,
International Journal of Soil Dynamics and Earthquake Engineering, 1985
This work investigated the control of chaotic behavior of a harmonically perturbed Duffing Oscill... more This work investigated the control of chaotic behavior of a harmonically perturbed Duffing Oscillator using vibration absorber. The systems of t wo degrees of freedom governing equations were simu lated nu mer ically using classical fourth order Runge-Kutta algorith m for a constant time step. The solution time history, phase plots and Poincare maps were used to validate the simu lation. Essentially, the details of the Poincare map were used numerically to determine the periodicity of Duffing oscillator for spectrum of mass ratio at a constant step of 0.001. The time h istory, phase plots and the Poincare at mass ratio (µ), absorber parameters (α a), and amp litude of excitation (F o) are in agreement with what is obtained in open literature. The chaotic response of the Duffing-Absorber system at α a = 1.1, F o = 0.21; and, taken respectively, the Duffing and the absorber initial conditions to be (1.0, 0.0) and (0.0, 0.0), this chaotic response was rendered periodic for some selected mass ratio (0≤µ≤1.0). Specifically, periods 1, 2 and 4 were obtained at µ= 0.208; these periodic responses were obtained at respective values of α a =1.1, α a =1.7803 and α a = 1.7595. In this work, eighty percent of the mass ratio selected did ensure that the chaotic behaviour of the Duffing-Absorber system is rendered periodic. Th is work demonstrated the practical utility of vibrat ion absorber as a chaotic oscillations control tool by the mass ratio approach; and having a recorded succes s of about eighty percent.
AbstractThe open-space damping system has been developed to preserve open space within the frame ... more AbstractThe open-space damping system has been developed to preserve open space within the frame of its installation. An earlier paper by the authors described its function, presented a theory to d...
CISM International Centre for Mechanical Sciences, 1994
Much progress has also been made in research and development of passive energy dissipation device... more Much progress has also been made in research and development of passive energy dissipation devices for structural applications. Similar to seismic isolation technology, the basic role of passive energy dissipation devices when incorporated into a structure is to absorb or consume a portion of the input energy, thereby reducing energy dissipation demand on primary structural members and minimizing possible structural damage. Unlike seismic isolation, however, these devices can be effective against wind excited motions as well as those due to earthquakes. In recent years, serious efforts have been undertaken to develop the concept of energy dissipation or supplemental damping into a workable technology, and a number of these devices have been installed in structures throughout the world. Active control research has a more recent origin. Active structural control is an area of structural protection in which the motion of a structure is controlled or modified by means of the action of a control system through some external energy supply. Considerable attention has been paid to active structural control research in recent years. It is now at the stage where actual systems have been designed,fabricated and installed in full-scale structures. This collection of lecture notes represents an attempt to introduce the basic concepts of these relatively new technologies, to provide a working knowledge of this exciting and fast expanding field, and to bring up-to-date current research and worldwide development in seismic isolation, passive energy dissipation, and active control. The book is divided into three parts, each addressing one of these topics. In each case, basic principles are introduced, followed by design and applications, implementation issues, case studies, and code issues if applicable.
Data recorded from dense seismic arrays such as the Large Scale Seismic Testing array in Lotung, ... more Data recorded from dense seismic arrays such as the Large Scale Seismic Testing array in Lotung, Taiwan, are used for multiple purposes, including development of attenuation and coherency functions, computing dynamic strains in soil, and estimating rotational components of ground motion. The required footprint of a seismic array deployed to compute rotational components of ground motion is a function of the method used for the computations and site specific characteristics, including the apparent seismic wave velocity and the frequency content of expected ground motions. A design procedure for a general two-dimensional seismic array is presented together with a site-specific example using the Surface Distribution Method to extract the rotational components of ground motion. A sensitivity study is performed to determine how the location of recording stations of translational motion in a dense array affects the computed rotational components of earthquake ground motion.
AbstractSeismic energy dissipation systems are typically installed in buildings within diagonal o... more AbstractSeismic energy dissipation systems are typically installed in buildings within diagonal or chevron bracing to improve the seismic performance by reducing drift, and under certain conditions...
Passive energy dissipation systems were developed in the United Stated either specifically for ci... more Passive energy dissipation systems were developed in the United Stated either specifically for civil engineering applications or they evolved from devices and materials used in industrial, automotive, military and aerospace applications. Yielding steel and frictional devices were specifically developed for structural applications, whereas viscoelastic dampers and fluid viscous devices were developed for other applications and adapted for structural applications.
The design of sliding isolation systems and relevant applications are presented. Sliding isolatio... more The design of sliding isolation systems and relevant applications are presented. Sliding isolation systems which found application are: (1) EDF system consisting of leaded bronze-stainless steel sliding bearings without restoring force, (2) TASS system consisting of PTFE-elastomeric sliding bearings and rubber restoring force devices, (3) Spherical sliding or Friction Pendulum System (FPS), (4) Lubricated PTFE sliding bearings with additional energy dissipating devices, and (5) Sliding bearings with restoring force devices for bridge applications.
This section describes the development and application of seismic (or base) isolation in the Unit... more This section describes the development and application of seismic (or base) isolation in the United States. Significant strides have been made in the implementation of the technology. This is attributed to recent advances in seismic isolation hardware and the removal of a number of impediments, which delayed widespread implementation in the near past.
Seismic isolation (also often referred to as base isolation) is a technique for mitigating the ef... more Seismic isolation (also often referred to as base isolation) is a technique for mitigating the effects of earthquakes on structures through the introduction of flexibility and energy absorption capability. Various practical means for introducing this desired flexibility and energy absorption capability are described.
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Papers by Michael Constantinou