Development of direct integration algorithms for structural dynamics using discrete control theory / Cheng Chen in Journal of engineering mechanics, Vol. 134 n°8 (Août 2008)  

Public ISBD [article]  inJournal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp. 676–683. Titre : Development of direct integration algorithms for structural dynamics using discrete control theory Type de document : texte imprimé Auteurs : Cheng Chen, Auteur ; James M. Ricles, Auteur Année de publication : 2008 Article en page(s) : pp. 676–683. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Algorithms Structural dynamics Transfer functions Stability Discrete elements Résumé : In structural dynamics, integration algorithms are often used to obtain the solution of temporally discretized equations of motion at selected time steps. Various time integration algorithms have been developed in the time domain using different methods. In order for an integration algorithm to be reliable it must be stable and accurate. A discrete transfer function is used to study the properties of integration algorithms. A pole mapping rule from control theory in conjunction with a discrete transfer function is used to develop new integration algorithms for obtaining solutions to structural dynamics problems. A new explicit integration algorithm, called the CR (Chen and Ricles) algorithm, is subsequently developed based on the proposed method. The properties of the algorithm are investigated and compared with other well established algorithms such as the Newmark family of integration algorithms. By assigning proper stable poles to the discrete transfer function the newly developed CR explicit algorithm is unconditionally stable and has the same accuracy as the Newmark method with constant acceleration. In addition, the CR algorithm is based on expressions for displacement and velocity that are both explicit in form, making it an appealing integration algorithm for solving structural dynamics problems. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A8%2867 [...] [article] Development of direct integration algorithms for structural dynamics using discrete control theory [texte imprimé] / Cheng Chen, Auteur ; James M. Ricles, Auteur . - 2008 . - pp. 676–683. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 134 n°8 (Août 2008) . - pp. 676–683. Mots-clés : Algorithms Structural dynamics Transfer functions Stability Discrete elements Résumé : In structural dynamics, integration algorithms are often used to obtain the solution of temporally discretized equations of motion at selected time steps. Various time integration algorithms have been developed in the time domain using different methods. In order for an integration algorithm to be reliable it must be stable and accurate. A discrete transfer function is used to study the properties of integration algorithms. A pole mapping rule from control theory in conjunction with a discrete transfer function is used to develop new integration algorithms for obtaining solutions to structural dynamics problems. A new explicit integration algorithm, called the CR (Chen and Ricles) algorithm, is subsequently developed based on the proposed method. The properties of the algorithm are investigated and compared with other well established algorithms such as the Newmark family of integration algorithms. By assigning proper stable poles to the discrete transfer function the newly developed CR explicit algorithm is unconditionally stable and has the same accuracy as the Newmark method with constant acceleration. In addition, the CR algorithm is based on expressions for displacement and velocity that are both explicit in form, making it an appealing integration algorithm for solving structural dynamics problems. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%290733-9399%282008%29134%3A8%2867 [...]

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Improved adaptive inverse compensation technique for real-time hybrid simulation / Cheng Chen in Journal of engineering mechanics, Vol. 138 N° 12 (Décembre 2012)  

Public ISBD [article]  inJournal of engineering mechanics > Vol. 138 N° 12 (Décembre 2012) . - pp. 1432–1446. Titre : Improved adaptive inverse compensation technique for real-time hybrid simulation Type de document : texte imprimé Auteurs : Cheng Chen, Auteur ; James M. Ricles, Auteur ; Tong Guo, Auteur Année de publication : 2013 Article en page(s) : pp. 1432–1446. Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Experimentation Hybrid methods Substructures Adaptive systems Résumé : Real-time hybrid simulation provides an economical and efficient experimental technique for performance evaluation of structures under earthquakes. A successful real-time hybrid simulation requires accurate actuator control in order to achieve reliable experimental results. The time delay as a result of servohydraulic dynamics, if not compensated for properly, would lead to inaccurate or even unstable simulation results. However, the nonlinearities in servohydraulic systems and experimental substructures make the actuator delay difficult to accurately estimate in practice. Therefore, actuator control presents a challenge for the application of the real-time hybrid simulation technique to earthquake engineering research. This paper presents an improved adaptive inverse compensation technique for real-time hybrid simulation. Two adaptive control laws based on a synchronization subspace plot are introduced to adjust the compensation parameters in order to minimize both phase and amplitude errors in the servohydraulic actuator response. The improved adaptive inverse compensation method is experimentally evaluated through real-time tests involving a large-scale magneto-rheological damper subjected to band-limited white noise–generated random displacements and variable current inputs. The experimental results are compared with the command displacements, with the error assessed using various evaluation criteria. The improved adaptive inverse compensation is compared with an existing adaptive inverse compensation method to demonstrate the improvement that the newly developed compensation method offers in minimizing actuator delay. The proposed improved adaptive inverse compensation method is demonstrated to further improve actuator control by reducing not only actuator tracking errors but also associated energy errors. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000450 [article] Improved adaptive inverse compensation technique for real-time hybrid simulation [texte imprimé] / Cheng Chen, Auteur ; James M. Ricles, Auteur ; Tong Guo, Auteur . - 2013 . - pp. 1432–1446. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 138 N° 12 (Décembre 2012) . - pp. 1432–1446. Mots-clés : Experimentation Hybrid methods Substructures Adaptive systems Résumé : Real-time hybrid simulation provides an economical and efficient experimental technique for performance evaluation of structures under earthquakes. A successful real-time hybrid simulation requires accurate actuator control in order to achieve reliable experimental results. The time delay as a result of servohydraulic dynamics, if not compensated for properly, would lead to inaccurate or even unstable simulation results. However, the nonlinearities in servohydraulic systems and experimental substructures make the actuator delay difficult to accurately estimate in practice. Therefore, actuator control presents a challenge for the application of the real-time hybrid simulation technique to earthquake engineering research. This paper presents an improved adaptive inverse compensation technique for real-time hybrid simulation. Two adaptive control laws based on a synchronization subspace plot are introduced to adjust the compensation parameters in order to minimize both phase and amplitude errors in the servohydraulic actuator response. The improved adaptive inverse compensation method is experimentally evaluated through real-time tests involving a large-scale magneto-rheological damper subjected to band-limited white noise–generated random displacements and variable current inputs. The experimental results are compared with the command displacements, with the error assessed using various evaluation criteria. The improved adaptive inverse compensation is compared with an existing adaptive inverse compensation method to demonstrate the improvement that the newly developed compensation method offers in minimizing actuator delay. The proposed improved adaptive inverse compensation method is demonstrated to further improve actuator control by reducing not only actuator tracking errors but also associated energy errors. ISSN : 0733-9399 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EM.1943-7889.0000450

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Improving the inverse compensation method for real-time hybrid simulation through a dual compensation scheme / Cheng Chen in Earthquake engineering structural dynamics, Vol. 38 N° 10 (Août 2009)  

Public ISBD [article]  inEarthquake engineering structural dynamics > Vol. 38 N° 10 (Août 2009) . - pp. 1237-1255 Titre : Improving the inverse compensation method for real-time hybrid simulation through a dual compensation scheme Type de document : texte imprimé Auteurs : Cheng Chen, Auteur ; James M. Ricles, Auteur Article en page(s) : pp. 1237-1255 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Real-time  Hybrid simulation  Actuator delay  delay compensation  Frequency response Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Real-time hybrid simulation combines experimental testing of physical substructure(s) and numerical simulation of analytical substructure(s), and thus enables the complete structural system to be considered during an experiment. Servo-hydraulic actuators are typically used to apply the command displacements to the physical substructure(s). Inaccuracy and instability can occur during a real-time hybrid simulation if the actuator delay due to servo-hydraulic dynamics is not properly compensated. Inverse compensation is a means to negate actuator delay due to inherent servo-hydraulic actuator dynamics during a real-time hybrid simulation. The success of inverse compensation requires the use of a known accurate value for the actuator delay. The actual actuator delay however may not be known before the simulation. An estimation based on previous experience has to be used, possibly leading to inaccurate experimental results. This paper presents a dual compensation scheme to improve the performance of the inverse compensation method when an inaccurately estimated actuator delay is used in the method. The dual compensation scheme modifies the predicted displacement from the inverse compensation procedure using the actuator tracking error. Frequency response analysis shows that the dual compensation scheme enables the inverse compensation method to compensate for actuator delay over a range of frequencies when an inaccurately estimated actuator delay is utilized. Real-time hybrid simulations of a single-degree-of-freedom system with an elastomeric damper are conducted to experimentally demonstrate the effectiveness of the dual compensation scheme. Exceptional experimental results are shown to be achieved using the dual compensation scheme without the knowledge of the actual actuator delay a priori. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe [article] Improving the inverse compensation method for real-time hybrid simulation through a dual compensation scheme [texte imprimé] / Cheng Chen, Auteur ; James M. Ricles, Auteur . - pp. 1237-1255. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N° 10 (Août 2009) . - pp. 1237-1255 Mots-clés : Real-time  Hybrid simulation  Actuator delay  delay compensation  Frequency response Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Real-time hybrid simulation combines experimental testing of physical substructure(s) and numerical simulation of analytical substructure(s), and thus enables the complete structural system to be considered during an experiment. Servo-hydraulic actuators are typically used to apply the command displacements to the physical substructure(s). Inaccuracy and instability can occur during a real-time hybrid simulation if the actuator delay due to servo-hydraulic dynamics is not properly compensated. Inverse compensation is a means to negate actuator delay due to inherent servo-hydraulic actuator dynamics during a real-time hybrid simulation. The success of inverse compensation requires the use of a known accurate value for the actuator delay. The actual actuator delay however may not be known before the simulation. An estimation based on previous experience has to be used, possibly leading to inaccurate experimental results. This paper presents a dual compensation scheme to improve the performance of the inverse compensation method when an inaccurately estimated actuator delay is used in the method. The dual compensation scheme modifies the predicted displacement from the inverse compensation procedure using the actuator tracking error. Frequency response analysis shows that the dual compensation scheme enables the inverse compensation method to compensate for actuator delay over a range of frequencies when an inaccurately estimated actuator delay is utilized. Real-time hybrid simulations of a single-degree-of-freedom system with an elastomeric damper are conducted to experimentally demonstrate the effectiveness of the dual compensation scheme. Exceptional experimental results are shown to be achieved using the dual compensation scheme without the knowledge of the actual actuator delay a priori. ISSN : 0098-8847 En ligne : www.interscience.wiley.com/journal/eqe

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Kinematic transformations for planar multi-directional pseudodynamic testing / Mercan, Oya in Earthquake engineering structural dynamics, Vol. 38 N° 9 (Juillet 2009)  

Public ISBD [article]  inEarthquake engineering structural dynamics > Vol. 38 N° 9 (Juillet 2009) . - pp. 1093-1119 Titre : Kinematic transformations for planar multi-directional pseudodynamic testing Type de document : texte imprimé Auteurs : Mercan, Oya, Auteur ; James M. Ricles, Auteur ; Sause, Richard, Auteur Article en page(s) : pp. 1093-1119 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Error detection  Kinematic correction  Multi-directional testing  Pseudodynamic test method  Test structure Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The pseudodynamic (PSD) test method imposes command displacements to a test structure for a given time step. The measured restoring forces and displaced position achieved in the test structure are then used to integrate the equations of motion to determine the command displacements for the next time step. Multi-directional displacements of the test structure can introduce error in the measured restoring forces and displaced position. The subsequently determined command displacements will not be correct unless the effects of the multi-directional displacements are considered. This paper presents two approaches for correcting kinematic errors in planar multi-directional PSD testing, where the test structure is loaded through a rigid loading block. The first approach, referred to as the incremental kinematic transformation method, employs linear displacement transformations within each time step. The second method, referred to as the total kinematic transformation method, is based on accurate nonlinear displacement transformations. Using three displacement sensors and the trigonometric law of cosines, this second method enables the simultaneous nonlinear equations that express the motion of the loading block to be solved without using iteration. The formulation and example applications for each method are given. Results from numerical simulations and laboratory experiments show that the total transformation method maintains accuracy, while the incremental transformation method may accumulate error if the incremental rotation of the loading block is not small over the time step. A procedure for estimating the incremental error in the incremental kinematic transformation method is presented as a means to predict and possibly control the error. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121641476/abstract [article] Kinematic transformations for planar multi-directional pseudodynamic testing [texte imprimé] / Mercan, Oya, Auteur ; James M. Ricles, Auteur ; Sause, Richard, Auteur . - pp. 1093-1119. Génie Civil Langues : Anglais (eng) in Earthquake engineering structural dynamics > Vol. 38 N° 9 (Juillet 2009) . - pp. 1093-1119 Mots-clés : Error detection  Kinematic correction  Multi-directional testing  Pseudodynamic test method  Test structure Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The pseudodynamic (PSD) test method imposes command displacements to a test structure for a given time step. The measured restoring forces and displaced position achieved in the test structure are then used to integrate the equations of motion to determine the command displacements for the next time step. Multi-directional displacements of the test structure can introduce error in the measured restoring forces and displaced position. The subsequently determined command displacements will not be correct unless the effects of the multi-directional displacements are considered. This paper presents two approaches for correcting kinematic errors in planar multi-directional PSD testing, where the test structure is loaded through a rigid loading block. The first approach, referred to as the incremental kinematic transformation method, employs linear displacement transformations within each time step. The second method, referred to as the total kinematic transformation method, is based on accurate nonlinear displacement transformations. Using three displacement sensors and the trigonometric law of cosines, this second method enables the simultaneous nonlinear equations that express the motion of the loading block to be solved without using iteration. The formulation and example applications for each method are given. Results from numerical simulations and laboratory experiments show that the total transformation method maintains accuracy, while the incremental transformation method may accumulate error if the incremental rotation of the loading block is not small over the time step. A procedure for estimating the incremental error in the incremental kinematic transformation method is presented as a means to predict and possibly control the error. ISSN : 0098-8847 En ligne : http://www3.interscience.wiley.com/journal/121641476/abstract

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Stability analysis of direct integration algorithms applied to MDOF nonlinear structural dynamics / Cheng Chen in Journal of engineering mechanics, Vol. 136 N° 4 (Avril 2010)  

Public ISBD [article]  inJournal of engineering mechanics > Vol. 136 N° 4 (Avril 2010) . - pp. 485-495 Titre : Stability analysis of direct integration algorithms applied to MDOF nonlinear structural dynamics Type de document : texte imprimé Auteurs : Cheng Chen, Auteur ; James M. Ricles, Auteur Article en page(s) : pp. 485-495 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Algorithms Transfer functions Stability Structural dynamics Dynamic loads. Résumé : Direct integration algorithms are typically used to solve temporally discretized equations of motion to evaluate the performance of structures under dynamic loading. The stability of these direct integration algorithms are usually investigated for linear elastic structures. However integration algorithms are often applied to structures with nonlinear behavior. This paper presents a procedure based on discrete control theory to investigate the stability of direct integration algorithms applied to multidegree-of-freedom (MDOF) nonlinear structures. The discrete root locus approach is used to investigate properties of the poles of the discrete transfer function matrix representing the nonlinear structural dynamics and to assess the stability of the integration algorithm. The procedure is illustrated using a nonlinear shear building MDOF system to investigate the stability of popular direct integration algorithms, including the Newmark family of integration algorithms, the Hilber-Hughes-Taylor alpha-method, and two newly developed explicit integration algorithms. Stability limits are derived for the direct integration algorithms that are found to be conditionally stable. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=ASCERL&smode=strres [...] [article] Stability analysis of direct integration algorithms applied to MDOF nonlinear structural dynamics [texte imprimé] / Cheng Chen, Auteur ; James M. Ricles, Auteur . - pp. 485-495. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 136 N° 4 (Avril 2010) . - pp. 485-495 Mots-clés : Algorithms Transfer functions Stability Structural dynamics Dynamic loads. Résumé : Direct integration algorithms are typically used to solve temporally discretized equations of motion to evaluate the performance of structures under dynamic loading. The stability of these direct integration algorithms are usually investigated for linear elastic structures. However integration algorithms are often applied to structures with nonlinear behavior. This paper presents a procedure based on discrete control theory to investigate the stability of direct integration algorithms applied to multidegree-of-freedom (MDOF) nonlinear structures. The discrete root locus approach is used to investigate properties of the poles of the discrete transfer function matrix representing the nonlinear structural dynamics and to assess the stability of the integration algorithm. The procedure is illustrated using a nonlinear shear building MDOF system to investigate the stability of popular direct integration algorithms, including the Newmark family of integration algorithms, the Hilber-Hughes-Taylor alpha-method, and two newly developed explicit integration algorithms. Stability limits are derived for the direct integration algorithms that are found to be conditionally stable. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=ASCERL&smode=strres [...]

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Stability analysis of direct integration algorithms applied to MDOF nonlinear structural dynamics / Cheng Chen in Journal of engineering mechanics, Vol. 134 n°9 (Septembre 2008)  

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Stability and accuracy analysis of outer loop dynamics in real-time pseudodynamic testing of SDOF systems / Mercan, Oya in Earthquake engineering structural dynamics, Vol. 36 N°11 (Octobre 2007)  

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Tracking error-based servohydraulic actuator adaptive compensation for real-time hybrid simulation / Cheng Chen in Journal of structural engineering, Vol. 136 N° 4 (Avril 2010)  

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