We revisit an attempt to establish a unified chronology of the first ca. 20 Myr of the Solar System in the light of recent data; this period encompasses the formation of the first solids and the earliest planetary processes. We investigate the consistency of calibrations of the chronometers based on the extinct radionuclides 26Al, 53Mn and 129I with one another and with the Pb–Pb chronometer. We find the most persuasive chronology to be that based on identifying isotopic closure of the three short–lived systems in Ste Marguerite with a common event; in effect, this modifies the calibration of the I–Xe system based on Acapulco phosphate. This can be tied, in turn, to an absolute time–scale based on the Pb–Pb and Mn–Cr ages of the angrite LEW86010. The result is a common chronology (agreement between I–Xe and Mn–Cr is particularly striking), although ages derived for calcium–aluminium–rich inclusions (CAIs) are discordant. This discordancy may be explained by nuclear effects in the CAI–formation region.
{"title":"A time–scale of formation of the first solids","authors":"J. Gilmour, J. Saxton","doi":"10.1098/rsta.2001.0895","DOIUrl":"https://doi.org/10.1098/rsta.2001.0895","url":null,"abstract":"We revisit an attempt to establish a unified chronology of the first ca. 20 Myr of the Solar System in the light of recent data; this period encompasses the formation of the first solids and the earliest planetary processes. We investigate the consistency of calibrations of the chronometers based on the extinct radionuclides 26Al, 53Mn and 129I with one another and with the Pb–Pb chronometer. We find the most persuasive chronology to be that based on identifying isotopic closure of the three short–lived systems in Ste Marguerite with a common event; in effect, this modifies the calibration of the I–Xe system based on Acapulco phosphate. This can be tied, in turn, to an absolute time–scale based on the Pb–Pb and Mn–Cr ages of the angrite LEW86010. The result is a common chronology (agreement between I–Xe and Mn–Cr is particularly striking), although ages derived for calcium–aluminium–rich inclusions (CAIs) are discordant. This discordancy may be explained by nuclear effects in the CAI–formation region.","PeriodicalId":20023,"journal":{"name":"Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73164214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The relatively high initial abundance of the short–lived radioisotope 26Al in calcium–aluminium–rich refractory inclusions found in meteorites is inconsistent with forming the 26Al by irradiation in the solar nebula, unless the inclusions are shielded from irradiation by a more volatile mantle. Nucleosynthesis of the 26Al in a stellar source, such as a supernova, remains a likely alternative explanation, coupled with rapid injection of the newly synthesized 26Al into the protosolar cloud. In order to retain the live 26Al, the protosolar cloud must then collapse to form the solar nebula in less than 1 Myr. These requirements lead to the hypothesis of the supernova–triggered collapse of the protosolar cloud and injection of supernova shock wave material into the cloud. Theoretical models of the interaction of interstellar shock waves with target protosolar clouds show that a distant supernova can both trigger collapse and inject ca. 10% of the shock wave material incident on the cloud through Rayleigh–Taylor fingers.
{"title":"Injection of newly synthesized elements into the protosolar cloud","authors":"A. Boss, H. Vanhala","doi":"10.1098/rsta.2001.0892","DOIUrl":"https://doi.org/10.1098/rsta.2001.0892","url":null,"abstract":"The relatively high initial abundance of the short–lived radioisotope 26Al in calcium–aluminium–rich refractory inclusions found in meteorites is inconsistent with forming the 26Al by irradiation in the solar nebula, unless the inclusions are shielded from irradiation by a more volatile mantle. Nucleosynthesis of the 26Al in a stellar source, such as a supernova, remains a likely alternative explanation, coupled with rapid injection of the newly synthesized 26Al into the protosolar cloud. In order to retain the live 26Al, the protosolar cloud must then collapse to form the solar nebula in less than 1 Myr. These requirements lead to the hypothesis of the supernova–triggered collapse of the protosolar cloud and injection of supernova shock wave material into the cloud. Theoretical models of the interaction of interstellar shock waves with target protosolar clouds show that a distant supernova can both trigger collapse and inject ca. 10% of the shock wave material incident on the cloud through Rayleigh–Taylor fingers.","PeriodicalId":20023,"journal":{"name":"Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85542373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We developed an on–line experimental system for conducting hybrid experiments in real time. It combines a computer, which conducts vibration simulation and generates a control signal, and a hydraulic actuator, which conducts a vibration experiment driven by the control signal. This system compensates for actuator delay and thus enables experiments to be carried out in real time. We evaluated the stability of the experiments with respect to the mass of the structure under excitation, and we developed a new method for compensating actuator delay in order to increase the stability condition. In this method, the compensated control signal is generated from the simulation results by using not only displacement but also velocity and acceleration. This method provides a stability criterion (allowable ratio of mass of the structure under excitation to that of a numerical model) about three times larger than that from the current method.
{"title":"A new method for compensating actuator delay in real–time hybrid experiments","authors":"Toshihiko Horiuchi, T. Konno","doi":"10.1098/rsta.2001.0878","DOIUrl":"https://doi.org/10.1098/rsta.2001.0878","url":null,"abstract":"We developed an on–line experimental system for conducting hybrid experiments in real time. It combines a computer, which conducts vibration simulation and generates a control signal, and a hydraulic actuator, which conducts a vibration experiment driven by the control signal. This system compensates for actuator delay and thus enables experiments to be carried out in real time. We evaluated the stability of the experiments with respect to the mass of the structure under excitation, and we developed a new method for compensating actuator delay in order to increase the stability condition. In this method, the compensated control signal is generated from the simulation results by using not only displacement but also velocity and acceleration. This method provides a stability criterion (allowable ratio of mass of the structure under excitation to that of a numerical model) about three times larger than that from the current method.","PeriodicalId":20023,"journal":{"name":"Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78882887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper describes the development and experimental implementation of a real–time earthquake simulation test method for large–scale structures. The method, effective force testing (EFT), is based on a transformation of coordinates, in which case the structure is fixed at the base (similar to the set–up for the pseudo–dynamic (PsD) test method); however, in the case of EFT, the method is based on a force–control algorithm rather than a displacement–control algorithm. Effective forces, equivalent to the mass of each storey level multiplied by the ground acceleration, are applied at each respective storey. As such, the EFT forces are known a priori for any ground acceleration record. As opposed to the PsD test method in which the ground displacements to be imposed are affected by the measured structural response as the stiffness changes. As in the case of the PsD test method, the EFT method is suitable for testing any type of structural system that can be idealized as a series of lumped masses (e.g. building or bridge structures). Research has been conducted on a linear elastic single–degree–of–freedom system at the University of Minnesota to develop and investigate implementation of the EFT method. A direct application of the EFT method was found to be ineffective because of a natural velocity feedback phenomenon between the actuator and the structure to which it is attached. A detailed model of the control, hydraulic and structural systems was developed to study the interaction problem and other nonlinear responses in the system. The implementation of an additional feedback loop using the measured velocity of the test structure was shown to be successful at overcoming the problems associated with actuator–ndash;control–ndash;structure interaction, indicating that EFT is a viable real–time method for seismic simulation studies.
{"title":"Development and implementation of the effective force testing method for seismic simulation of large–scale structures","authors":"C. Shield, C. French, John Timm","doi":"10.1098/rsta.2001.0879","DOIUrl":"https://doi.org/10.1098/rsta.2001.0879","url":null,"abstract":"This paper describes the development and experimental implementation of a real–time earthquake simulation test method for large–scale structures. The method, effective force testing (EFT), is based on a transformation of coordinates, in which case the structure is fixed at the base (similar to the set–up for the pseudo–dynamic (PsD) test method); however, in the case of EFT, the method is based on a force–control algorithm rather than a displacement–control algorithm. Effective forces, equivalent to the mass of each storey level multiplied by the ground acceleration, are applied at each respective storey. As such, the EFT forces are known a priori for any ground acceleration record. As opposed to the PsD test method in which the ground displacements to be imposed are affected by the measured structural response as the stiffness changes. As in the case of the PsD test method, the EFT method is suitable for testing any type of structural system that can be idealized as a series of lumped masses (e.g. building or bridge structures). Research has been conducted on a linear elastic single–degree–of–freedom system at the University of Minnesota to develop and investigate implementation of the EFT method. A direct application of the EFT method was found to be ineffective because of a natural velocity feedback phenomenon between the actuator and the structure to which it is attached. A detailed model of the control, hydraulic and structural systems was developed to study the interaction problem and other nonlinear responses in the system. The implementation of an additional feedback loop using the measured velocity of the test structure was shown to be successful at overcoming the problems associated with actuator–ndash;control–ndash;structure interaction, indicating that EFT is a viable real–time method for seismic simulation studies.","PeriodicalId":20023,"journal":{"name":"Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73060516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a test system for conducting online (pseudo–dynamic) tests on a real time–scale. A historical perspective is provided regarding the development of such testing, and a real–time online test system devised by the writer is introduced. The proposed system is characterized by (1) use of a digital signal processor now readily available; (2) adoption of the C language to ensure easy programming; and (3) separation of response analysis and displacement signal generation to allow the testing with complex structures. A five–storey base–isolated building model, treated as a six–degrees–of–freedom structure, was tested for various ground motions. The tests demonstrated that the system is able to simulate earthquake responses involving large displacements and velocities as well as complex numerical hystereses. Advantages and drawbacks of the real–time online test are discussed in reference to other experimental techniques: the quasi–static loading test using a predetermined loading history, the shaking–table test and the conventional quasi–static loading online test. Areas that require further research for advancement and refinement of the real–time online test are also noted.
{"title":"Development, potential, and limitations of real–time online (pseudo–dynamic) testing","authors":"M. Nakashima","doi":"10.1098/rsta.2001.0876","DOIUrl":"https://doi.org/10.1098/rsta.2001.0876","url":null,"abstract":"This paper presents a test system for conducting online (pseudo–dynamic) tests on a real time–scale. A historical perspective is provided regarding the development of such testing, and a real–time online test system devised by the writer is introduced. The proposed system is characterized by (1) use of a digital signal processor now readily available; (2) adoption of the C language to ensure easy programming; and (3) separation of response analysis and displacement signal generation to allow the testing with complex structures. A five–storey base–isolated building model, treated as a six–degrees–of–freedom structure, was tested for various ground motions. The tests demonstrated that the system is able to simulate earthquake responses involving large displacements and velocities as well as complex numerical hystereses. Advantages and drawbacks of the real–time online test are discussed in reference to other experimental techniques: the quasi–static loading test using a predetermined loading history, the shaking–table test and the conventional quasi–static loading online test. Areas that require further research for advancement and refinement of the real–time online test are also noted.","PeriodicalId":20023,"journal":{"name":"Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90192234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A multi–axial shaking table is normally used for earthquake simulation and the dynamic qualification of structures. In most cases the same set–up can also be used for a modal identification of the tested structure. However, this requires the application of suitable modal identification methods. Here, the theory and the basic principles of modal identification by multi–axial base excitation are described. Starting with the relative kinematics and the fundamental dynamic relationships, the specifics of base excitation are explained. Equations for the structural responses and the dynamic forces at the interface are presented and discussed. A survey of identification approaches developed at DLR, Gottingen is given. A frequency– and a time–domain method are described in more detail and illustrated by their application to a laboratory structure. The frequency–domain method is best suited for a general and reliable modal identification, whereas the time–domain method is capable of analysing transient vibrations. Also, the frequency–domain identification of a larger structure is outlined.
{"title":"Utilization of multi–axial shaking tables for the modal identification of structures","authors":"U. Füllekrug","doi":"10.1098/rsta.2001.0872","DOIUrl":"https://doi.org/10.1098/rsta.2001.0872","url":null,"abstract":"A multi–axial shaking table is normally used for earthquake simulation and the dynamic qualification of structures. In most cases the same set–up can also be used for a modal identification of the tested structure. However, this requires the application of suitable modal identification methods. Here, the theory and the basic principles of modal identification by multi–axial base excitation are described. Starting with the relative kinematics and the fundamental dynamic relationships, the specifics of base excitation are explained. Equations for the structural responses and the dynamic forces at the interface are presented and discussed. A survey of identification approaches developed at DLR, Gottingen is given. A frequency– and a time–domain method are described in more detail and illustrated by their application to a laboratory structure. The frequency–domain method is best suited for a general and reliable modal identification, whereas the time–domain method is capable of analysing transient vibrations. Also, the frequency–domain identification of a larger structure is outlined.","PeriodicalId":20023,"journal":{"name":"Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86484716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Blakeborough, Mary R. Williams, A. Darby, David R. Williams
Full–scale dynamic testing of civil engineering structures is extremely costly and difficult to perform. Most test methods therefore involve either a reduction in the physical scale or an extension of the time–scale. Both of these approaches can cause significant difficulties in extrapolating to the full–scale dynamic behaviour, particularly when the structure responds nonlinearly or includes highly rate–dependent components such as dampers. Real–time substructure testing is a relatively new method which seeks to avoid these problems by performing tests on key elements of the structure at full or large scale, with the physical test coupled in real time to a numerical model of the surrounding structure. The method requires a high performance of both the physical test equipment and the numerical algorithms. This paper first reviews the development of structural test methods and the emergence of real–time substructure testing. This is followed by a brief description of the equipment that is needed to implement a substructure test. Several novel developments in the numerical algorithms used in real–time substructure testing are presented, including a new, fast algorithm which allows nonlinear response of the surrounding structure to be computed in real time. Results are presented from a variety of tests which demonstrate the performance of the system at small and large scale, with either linear or nonlinear test specimens, and with varying numbers of degrees of freedom passed between the physical and numerical substructures. Finally, the usefulness and possible applications of the test method are discussed.
{"title":"The development of real–time substructure testing","authors":"A. Blakeborough, Mary R. Williams, A. Darby, David R. Williams","doi":"10.1098/rsta.2001.0877","DOIUrl":"https://doi.org/10.1098/rsta.2001.0877","url":null,"abstract":"Full–scale dynamic testing of civil engineering structures is extremely costly and difficult to perform. Most test methods therefore involve either a reduction in the physical scale or an extension of the time–scale. Both of these approaches can cause significant difficulties in extrapolating to the full–scale dynamic behaviour, particularly when the structure responds nonlinearly or includes highly rate–dependent components such as dampers. Real–time substructure testing is a relatively new method which seeks to avoid these problems by performing tests on key elements of the structure at full or large scale, with the physical test coupled in real time to a numerical model of the surrounding structure. The method requires a high performance of both the physical test equipment and the numerical algorithms. This paper first reviews the development of structural test methods and the emergence of real–time substructure testing. This is followed by a brief description of the equipment that is needed to implement a substructure test. Several novel developments in the numerical algorithms used in real–time substructure testing are presented, including a new, fast algorithm which allows nonlinear response of the surrounding structure to be computed in real time. Results are presented from a variety of tests which demonstrate the performance of the system at small and large scale, with either linear or nonlinear test specimens, and with varying numbers of degrees of freedom passed between the physical and numerical substructures. Finally, the usefulness and possible applications of the test method are discussed.","PeriodicalId":20023,"journal":{"name":"Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79036183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Traditional shaking–table testing has been limited by the effectiveness of conventional fixed–gain algorithms used in their control. These algorithms are normally based on linear models of the shaking table and specimen, whose parameters are assumed to be fixed for the duration of the test. Although the influence of the specimen in the overall system dynamics can be partly removed by fine–tuning the linear controller, this process cannot deal with nonlinear effects and is limited in scope by the expertise of the operator. The minimal control synthesis (MCS) algorithm is a form of adaptive control, which was originally and successfully employed to cope with the nonlinear problems in the field of robotics. The MCS algorithm can tune the controller in real–time without any parametric knowledge of the system to be controlled. This paper describes how MCS has been incorporated within both analog and digital controllers for shaking tables and shows some of the results achieved on tables at the University of Bristol and at Athens Technical University. In both cases, the introduction of adaptive control has noticeably improved the performance of the shaking table, correcting errors by more than 5 dB in some experiments.
{"title":"Adaptive control of shaking tables using the minimal control synthesis algorithm","authors":"D. Stoten, E. Gómez","doi":"10.1098/rsta.2001.0862","DOIUrl":"https://doi.org/10.1098/rsta.2001.0862","url":null,"abstract":"Traditional shaking–table testing has been limited by the effectiveness of conventional fixed–gain algorithms used in their control. These algorithms are normally based on linear models of the shaking table and specimen, whose parameters are assumed to be fixed for the duration of the test. Although the influence of the specimen in the overall system dynamics can be partly removed by fine–tuning the linear controller, this process cannot deal with nonlinear effects and is limited in scope by the expertise of the operator. The minimal control synthesis (MCS) algorithm is a form of adaptive control, which was originally and successfully employed to cope with the nonlinear problems in the field of robotics. The MCS algorithm can tune the controller in real–time without any parametric knowledge of the system to be controlled. This paper describes how MCS has been incorporated within both analog and digital controllers for shaking tables and shows some of the results achieved on tables at the University of Bristol and at Athens Technical University. In both cases, the introduction of adaptive control has noticeably improved the performance of the shaking table, correcting errors by more than 5 dB in some experiments.","PeriodicalId":20023,"journal":{"name":"Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89908891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper describes a concerted performance appraisal of four of Europe's large shaking tables. Three of the shaking tables were capable of controlled motion in all six degrees of freedom, while the fourth was constrained to move in the three translational axes only. The principal study was the fidelity of the input motion at the testpiece. At all four tables this was found to be satisfactory, but, in one case, the time taken for the tuning process was often more than one hour, and in all cases highly trained and experienced operators were required. Even so, the tuning process was ‘out of real time’, which required that the physical properties of the testpiece should not change during the tuning process. This meant that controlled nonlinear specimen behaviour could not be studied experimentally. This was a major drawback, since modern economic design requires use of nonlinear material properties, leading to progressive failure of redundant members, but not total collapse. The studies did, however, have a major beneficial effect in showing that existing control systems were out of date. Further research programmes were therefore started which have already had the major consequence of producing ‘real–time’ control of shaking tables.
{"title":"The European collaborative programme on evaluating the performance of shaking tables","authors":"A. Crewe, R. T. Severn","doi":"10.1098/rsta.2001.0861","DOIUrl":"https://doi.org/10.1098/rsta.2001.0861","url":null,"abstract":"This paper describes a concerted performance appraisal of four of Europe's large shaking tables. Three of the shaking tables were capable of controlled motion in all six degrees of freedom, while the fourth was constrained to move in the three translational axes only. The principal study was the fidelity of the input motion at the testpiece. At all four tables this was found to be satisfactory, but, in one case, the time taken for the tuning process was often more than one hour, and in all cases highly trained and experienced operators were required. Even so, the tuning process was ‘out of real time’, which required that the physical properties of the testpiece should not change during the tuning process. This meant that controlled nonlinear specimen behaviour could not be studied experimentally. This was a major drawback, since modern economic design requires use of nonlinear material properties, leading to progressive failure of redundant members, but not total collapse. The studies did, however, have a major beneficial effect in showing that existing control systems were out of date. Further research programmes were therefore started which have already had the major consequence of producing ‘real–time’ control of shaking tables.","PeriodicalId":20023,"journal":{"name":"Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87608491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Shortreed, F. Seible, A. Filiatrault, G. Benzoni
The California Department of Transportation (Caltrans) has recently commissioned a Seismic Response Modification Device (SRMD) Test System, housed in the Department of Structural Engineering at the University of California, San Diego. This facility is being used to test and characterize various isolation bearings, dampers and lock–up devices scheduled for use in the seismic retrofits of several large California bridges. This state–of–the–art, six–degree–of–freedom seismic testing system incorporates many new concepts in earthquake simulation system design. The results of the initial shake–down characterization testing are presented, a model to predict the machine's inertial and frictional characteristics is developed, and the initial testing results of some SRMD isolation bearing specimens are presented.
{"title":"Characterization and testing of the Caltrans Seismic Response Modification Device Test System","authors":"J. Shortreed, F. Seible, A. Filiatrault, G. Benzoni","doi":"10.1098/rsta.2001.0875","DOIUrl":"https://doi.org/10.1098/rsta.2001.0875","url":null,"abstract":"The California Department of Transportation (Caltrans) has recently commissioned a Seismic Response Modification Device (SRMD) Test System, housed in the Department of Structural Engineering at the University of California, San Diego. This facility is being used to test and characterize various isolation bearings, dampers and lock–up devices scheduled for use in the seismic retrofits of several large California bridges. This state–of–the–art, six–degree–of–freedom seismic testing system incorporates many new concepts in earthquake simulation system design. The results of the initial shake–down characterization testing are presented, a model to predict the machine's inertial and frictional characteristics is developed, and the initial testing results of some SRMD isolation bearing specimens are presented.","PeriodicalId":20023,"journal":{"name":"Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86002980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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