The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Aoli Zhang - One of the best experts on this subject based on the ideXlab platform.
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delayed proportional integral control for offshore Steel Jacket platforms
Journal of The Franklin Institute-engineering and Applied Mathematics, 2019Co-Authors: Aoli Zhang, Zhihui Cai, Shouwa Gao, Gongyou TangAbstract:Abstract This paper is concerned with the problem of delayed proportional-integral control of an offshore platform subject to self-excited nonlinear hydrodynamic force. By using current and distributed delayed states, a delayed proportional-integral controller is designed to stabilize the offshore platform. Under such a controller, the closed-loop system of the offshore platform is modeled as a nonlinear system with discrete and distributed delays, which allows us to employ the Lyapnov–Krasovskii functional method to analyze its asymptotic stability. Since an affine Wirtinger-based inequality is exploited to estimate the derivative of the Lyapunov–Krasovskii functional, a new stability criterion for the closed-loop system is derived, based on which, suitable control gains can be designed provided that a set of linear matrix inequalities are feasible. It is found through simulation results that the proposed control scheme can improve the control performance remarkably. Moreover, (i) compared with the existing delay-free controllers, the proposed controller can reduce the required control force and the oscillation amplitudes of the platform significantly; and (ii) compared with several delayed controllers, the proposed controller requires less control cost.
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robust non fragile sampled data control for offshore Steel Jacket platforms
Nonlinear Dynamics, 2016Co-Authors: Aoli Zhang, Maomao Meng, Xianming ZhangAbstract:This paper is concerned with the non-fragile sampled-data control problem for an offshore platform subject to parametric perturbations of the system and admissible gain variations of the controller. By purposefully introducing a time-varying time-delay into control channel, designing a sampled-data controller for the original system is transformed into synthesizing a state feedback controller for a time-varying time-delay system. A sufficient condition on the existence of a robust non-fragile sampled-data controller is derived. Then, a robust non-fragile sampled-data controller is designed and its effectiveness is investigated based on the simulation results. It is demonstrated that (1) the designed non-fragile sampled-data controller is capable of reducing the oscillation amplitudes of the floors of the offshore platform system significantly; and (2) compared with the robust sampled-data controller and the classical robust controller as well as the robust delayed controller, the oscillation amplitudes of the floors of the system under the three controllers are almost at the same level, while the control force required by the robust sampled-data controller is less than the one by the continuous-time controllers.
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optimal tracking control with feedforward compensation for offshore Steel Jacket platforms with active mass damper mechanisms
Journal of Vibration and Control, 2016Co-Authors: Aoli Zhang, Yujia Liu, Gongyou TangAbstract:This paper presents the optimal tracking control methodology for an offshore Steel Jacket platform subject to external wave force. Based on a dynamic model of an offshore Steel Jacket platform with...
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robust sampled data h control for offshore Steel Jacket platforms
Conference of the Industrial Electronics Society, 2015Co-Authors: Maomao Meng, Xianming Zhang, Aoli Zhang, Haihong WangAbstract:This paper is concerned with the problem of the robust sampled-data H∞ control for an offshore Steel Jacket platform subject to the self-excited wave force and the external disturbance. First, by using the input delay method, the corresponding closed-loop system with the sampling measurements is transformed into a continuous-time system. Then, based on a Lyapunov functional, the H∞ performance is established and the stability criteria for the closed-loop system is derived. Finally, the effectiveness of the proposed robust sampled-data H∞ controller is demonstrated by a simulation example. The simulation results show that the designed controller is effective to control the offshore platform, Moreover, to obtain almost the same control performance, the required control force under the robust sampled-data H∞ controller is smaller than the one under the robust H∞ controller.
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delayed non fragile h control for offshore Steel Jacket platforms
Journal of Vibration and Control, 2015Co-Authors: Aoli Zhang, Zuowu HuangAbstract:This paper is concerned with a delayed non-fragile H∞ control scheme for an offshore Steel Jacket platform subject to self-excited nonlinear hydrodynamic force and external disturbance. By intentionally introducing a time-delay into the control channel, a delayed robust non-fragile H∞ controller is designed to reduce the vibration amplitudes of the offshore platform. The positive effects of the time delays on the non-fragile H∞ control for the offshore platform are investigated. It is shown through simulation results that (i) the proposed delayed non-fragile H∞ controller is effective to attenuate the vibration of the offshore platform; (ii) the control force required by the delayed non-fragile H∞ controller is smaller than that required by the delay-free non-fragile H∞ controller; (iii) the time delays can be used to improve the control performance of the offshore platform.
Gongyou Tang - One of the best experts on this subject based on the ideXlab platform.
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delayed proportional integral control for offshore Steel Jacket platforms
Journal of The Franklin Institute-engineering and Applied Mathematics, 2019Co-Authors: Aoli Zhang, Zhihui Cai, Shouwa Gao, Gongyou TangAbstract:Abstract This paper is concerned with the problem of delayed proportional-integral control of an offshore platform subject to self-excited nonlinear hydrodynamic force. By using current and distributed delayed states, a delayed proportional-integral controller is designed to stabilize the offshore platform. Under such a controller, the closed-loop system of the offshore platform is modeled as a nonlinear system with discrete and distributed delays, which allows us to employ the Lyapnov–Krasovskii functional method to analyze its asymptotic stability. Since an affine Wirtinger-based inequality is exploited to estimate the derivative of the Lyapunov–Krasovskii functional, a new stability criterion for the closed-loop system is derived, based on which, suitable control gains can be designed provided that a set of linear matrix inequalities are feasible. It is found through simulation results that the proposed control scheme can improve the control performance remarkably. Moreover, (i) compared with the existing delay-free controllers, the proposed controller can reduce the required control force and the oscillation amplitudes of the platform significantly; and (ii) compared with several delayed controllers, the proposed controller requires less control cost.
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optimal tracking control with feedforward compensation for offshore Steel Jacket platforms with active mass damper mechanisms
Journal of Vibration and Control, 2016Co-Authors: Aoli Zhang, Yujia Liu, Gongyou TangAbstract:This paper presents the optimal tracking control methodology for an offshore Steel Jacket platform subject to external wave force. Based on a dynamic model of an offshore Steel Jacket platform with...
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discrete feedforward and feedback optimal tracking control for offshore Steel Jacket platforms
Ocean Engineering, 2014Co-Authors: Aoli Zhang, Yujia Liu, Gongyou TangAbstract:This paper is concerned with discrete feedforward and feedback optimal tracking control schemes for an offshore Steel Jacket platform subject to irregular wave force. By discretizing a dynamic model of the offshore Steel Jacket platform system, a discrete feedforward and feedback optimal tracking controller is developed first to attenuate the wave-induced vibration of the offshore platform. Then, for the case of the offshore platform with control delays, a discrete feedforward and feedback optimal tracking controller with memory is presented. The controllers can be designed by solving an algebraic Riccati equation and a Stein equation, respectively. It is found through simulation results that compared with the classic state feedback optimal tracking control schemes, the proposed control schemes are more efficient in attenuating the vibration of the offshore platform. In addition, compared with the feedforward and feedback optimal control schemes, the proposed control schemes require less control cost.
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active vibration h control of offshore Steel Jacket platforms using delayed feedback
Journal of Sound and Vibration, 2013Co-Authors: Baolin Zhang, Gongyou TangAbstract:Abstract This paper is concerned with delayed H ∞ control for an offshore Steel Jacket platforms subject to external wave force. By artificially introducing a proper time-delay into control channel, a delayed H ∞ controller is designed to attenuate the wave-induced vibration of the offshore platform and thereby improve the control performance of the system. The problem of the controller design is transformed into a nonlinear minimization problem. It is shown through simulation results that compared with the delay-free H ∞ control scheme, the vibration amplitudes of the offshore Steel Jacket platform with the delayed H ∞ control scheme are in the same level as the ones with the delay-free H ∞ control scheme, while the required control force by the delayed H ∞ control scheme is much smaller than that by the delay-free H ∞ control scheme. Compared with the feedforward and feedback optimal control scheme, both the vibration amplitudes of the offshore platform and the required control force with the delayed H ∞ control scheme are smaller than the ones with the feedforward and feedback optimal control scheme.
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wave force attenuation control for offshore Steel Jacket platforms via optimal guaranteed cost sliding mode schemes
Chinese Control and Decision Conference, 2013Co-Authors: Aoli Zhang, Gongyou TangAbstract:This paper is concerned with optimal guaranteed cost sliding mode control for an offshore Steel Jacket platform subject to nonlinear self-excited wave force. A nonlinear quadratic performance index which directly associates with the wave force is introduced first. Then, by combining the guaranteed cost control scheme and the integral sliding mode control scheme, an optimal guaranteed cost sliding mode controller is proposed to attenuate the wave force and improve the performance of the offshore platform. It is shown through simulation results that the oscillation amplitudes of the offshore platform under the optimal guaranteed cost sliding mode controller are small than those under the integral sliding mode controller and the delayed dynamic output feedback controller. Moreover, the required control force by the optimal guaranteed cost sliding mode controller is less than the ones by the integral sliding mode controller and the delayed dynamic output feedback controller.
Xianming Zhang - One of the best experts on this subject based on the ideXlab platform.
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robust non fragile sampled data control for offshore Steel Jacket platforms
Nonlinear Dynamics, 2016Co-Authors: Aoli Zhang, Maomao Meng, Xianming ZhangAbstract:This paper is concerned with the non-fragile sampled-data control problem for an offshore platform subject to parametric perturbations of the system and admissible gain variations of the controller. By purposefully introducing a time-varying time-delay into control channel, designing a sampled-data controller for the original system is transformed into synthesizing a state feedback controller for a time-varying time-delay system. A sufficient condition on the existence of a robust non-fragile sampled-data controller is derived. Then, a robust non-fragile sampled-data controller is designed and its effectiveness is investigated based on the simulation results. It is demonstrated that (1) the designed non-fragile sampled-data controller is capable of reducing the oscillation amplitudes of the floors of the offshore platform system significantly; and (2) compared with the robust sampled-data controller and the classical robust controller as well as the robust delayed controller, the oscillation amplitudes of the floors of the system under the three controllers are almost at the same level, while the control force required by the robust sampled-data controller is less than the one by the continuous-time controllers.
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robust sampled data h control for offshore Steel Jacket platforms
Conference of the Industrial Electronics Society, 2015Co-Authors: Maomao Meng, Xianming Zhang, Aoli Zhang, Haihong WangAbstract:This paper is concerned with the problem of the robust sampled-data H∞ control for an offshore Steel Jacket platform subject to the self-excited wave force and the external disturbance. First, by using the input delay method, the corresponding closed-loop system with the sampling measurements is transformed into a continuous-time system. Then, based on a Lyapunov functional, the H∞ performance is established and the stability criteria for the closed-loop system is derived. Finally, the effectiveness of the proposed robust sampled-data H∞ controller is demonstrated by a simulation example. The simulation results show that the designed controller is effective to control the offshore platform, Moreover, to obtain almost the same control performance, the required control force under the robust sampled-data H∞ controller is smaller than the one under the robust H∞ controller.
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sliding mode control with mixed current and delayed states for offshore Steel Jacket platforms
IEEE Transactions on Control Systems and Technology, 2014Co-Authors: Aoli Zhang, Xianming ZhangAbstract:This paper is concerned with active control for an offshore Steel Jacket platform subjected to wave-induced force and parameter perturbations. An uncertain dynamic model for the offshore platform is first established, where uncertainties not only on the natural frequency and the damping ratio of both the offshore platform and the active tuned mass damper (TMD) but also on the damping and stiffness of the TMD are considered. Then, by intentionally introducing a proper time delay into the control channel, a novel sliding mode control scheme is proposed. This scheme uses information about mixed current and delayed states. It is shown through simulation results that this scheme is more effective in both improving the control performance and reducing control force of the offshore platform than some existing ones, such as delay-free sliding mode control, nonlinear control, dynamic output feedback control, and delayed dynamic output feedback control. Furthermore, it is shown that the introduced time delay in this scheme can take values in different ranges while the corresponding control performance of the offshore platform is almost at the same level.
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integral sliding mode control for offshore Steel Jacket platforms
Journal of Sound and Vibration, 2012Co-Authors: Baolin Zhang, Xianming Zhang, Xinghuo YuAbstract:Abstract This paper is concerned with robust integral sliding mode control for an offshore Steel Jacket platforms subject to nonlinear wave-induced force and parameter perturbations. A robust integral sliding mode controller is designed to stabilize the dynamic model of the offshore Steel Jacket platform. It is shown through simulation results that the robust integral sliding mode control scheme can reduce the internal oscillations of the offshore Steel Jacket platform dramatically; and the performance of the offshore Steel Jacket platform under the robust integral sliding mode control scheme is better than the ones under the nonlinear control scheme and the dynamic output feedback control scheme.
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effects of small time delays on dynamic output feedback control of offshore Steel Jacket structures
Journal of Sound and Vibration, 2011Co-Authors: Xianming ZhangAbstract:This paper investigates the effect of a small time-delay on dynamic output feedback control of an offshore Steel Jacket structure subject to a nonlinear wave-induced force. First, a conventional dynamic output feedback controller is designed to reduce the internal oscillations of the offshore structure. It is found that the designed controller is of a larger gain in the sense of Euclidean norm, which demands a larger control force. Second, a small time-delay is introduced intentionally to design a new dynamic output feedback controller such that (i) the controller is of a small gain in the sense of Euclidean norm and (ii) the internal oscillations of the offshore structure can be dramatically reduced. It is shown through simulation results that purposefully introducing time-delays can be used to improve control performance.
Qingju Che - One of the best experts on this subject based on the ideXlab platform.
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seismic behaviour of Steel Jacket retrofitted reinforced concrete columns with recycled aggregate concrete
Construction and Building Materials, 2018Co-Authors: Jia Cai, Qingju Che, Xinpei Liu, Peizhou Huang, Xuli TangAbstract:Abstract This paper presents the experimental and numerical investigations on the seismic behaviour of Steel-Jacket retrofitted reinforced concrete (SJRRC) columns with recycled aggregate concrete (RAC). An unstrengthened reinforced concrete (RC) column and nine SJRRC columns tested under lateral cyclic loading are reported. The experimental results manifest that by using the Steel-Jacket retrofitting approach with RAC, the initial stiffness, ultimate strength, deformation ductility and energy dissipation ability of the columns are improved significantly. The peak strengths of the SJRRC columns are about 1.86–3.44 times of the counterpart of the original RC column. The retrofitted columns also show ductile post-peak load behaviour with the ductility coefficients ranging between 4.05 and 7.93. As the applied axial compressive loads increase, the failure mode of the SJRRC specimens is transited gradually from tension-controlled failure to compression-controlled failure. The specimens failed in compression-controlled mode exhibit plumper hysteresis curves, better energy dissipation ability, and higher secant stiffness than those failed in tension-controlled mode. The specimen having 100% recycled coarse aggregate replacement ratio has slightly lower lateral strength and secant stiffness than the specimens with 0% or 50% recycled coarse aggregate replacement ratio, and shows more serious pinching effect on its hysteresis curve. The effects of the preload and pre-damage of original column could be unfavourable on the cyclic performance of retrofitted column. The finite element analyses are also performed to further investigate the lateral behaviour of SJRRC columns. The proposed finite element model is validated by a comparison with the experimental results. By using the developed finite element model, parameter studies are undertaken and indicate that the applied axial compressive load and the thickness of Steel Jacket are the dominant factors affecting the lateral performance of SJRRC column.
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axial compressive behaviour of Steel Jacket retrofitted rc columns with recycled aggregate concrete
Construction and Building Materials, 2017Co-Authors: Jia Cai, Qingju Che, Xinpei Liu, Hua XueAbstract:Abstract It is an effective solution to strengthen structural column by using Steel Jacket and infill concrete for reinforced concrete (RC) structure retrofitting. In this research, the recycled aggregate concrete (RAC) is adopted as an infill concrete instead of using the normal concrete, in order to reduce the carbon footprint of construction. Fifteen columns including twelve Steel-Jacket strengthened columns, one unstrengthened column and two concrete filled Steel tube (CFST) columns are tested to investigate the axial compressive behaviour of Steel-Jacket retrofitted RC columns with RAC. The variables among the tested specimens include the recycled coarse aggregate replacement ratio, RAC strength, Steel tube thickness and preload of original column. Experimental results illustrate that using Steel Jacketing approach for retrofitting could significantly improve the strength, stiffness and ductility of the columns. The axial compressive strength of the Steel-Jacket retrofitted column with RAC is slightly lower than the one with normal infill concrete, but the influence of recycled coarse aggregate replacement ratios is negligible. The peak strengths of Steel-Jacket retrofitted columns can be significantly enhanced by increasing the thickness of Steel tube. The performances of the Steel-Jacket retrofitted columns are similar to that of the CFST columns. The effect of the preload of original column on the ultimate strength of Steel-Jacket retrofitted column is limited. A finite element (FE) model is also developed by using ABAQUS software to simulate the performance of Steel-Jacket retrofitted columns. The accuracy of the model is validated through comparing with the experimental results. By using the developed FE model, the mechanical behaviour of the column is further discussed in details and extended parametric studies are undertaken to elucidate the effects of various influencing factors on the behaviour of the column and its components. The design methods for predicting the axial compressive strength of the retrofitted column with RAC are suggested.
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behaviour of Steel Jacket retrofitted rc columns with preload effects
Thin-walled Structures, 2016Co-Authors: Jia Cai, Qingju Che, Xinpei LiuAbstract:Abstract Steel Jacketing is an efficient way to retrofit reinforced concrete columns. Previous studies focused on the performance improvement without considering the preloads on the original columns. The preloads might inevitably affect the structural performance of the retrofitted columns. Comprehensive experimental and numerical studies on the behaviour of Steel-Jacket retrofitted RC columns with preload effects are presented in this paper. Twenty-nine Steel Jacketing columns with different Steel tube thicknesses, axial preloading levels and load eccentricities are tested under concentrically or eccentrically compressive loading. The experimental results are discussed and illustrate that the effects of preloading levels on the axial compression strength of the retrofitted columns are negligible while increasing the preloads could decrease the eccentric compressive strength. A fibre element model is developed to predict the behaviour of the retrofitted columns. The material non-linear behaviour of all the components considering the Steel tube and stirrup confining effects on the concrete as well as the preloading action are taken into account in the model. The model is validated by comparing its results with the experimental results. Extensive parametric studies are undertaken by using the proposed numerical model to elucidate the effects of axial and moment preloading and the effects of preloads with various other parameters on the performance of the retrofitted columns.
Jia Cai - One of the best experts on this subject based on the ideXlab platform.
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seismic behaviour of Steel Jacket retrofitted reinforced concrete columns with recycled aggregate concrete
Construction and Building Materials, 2018Co-Authors: Jia Cai, Qingju Che, Xinpei Liu, Peizhou Huang, Xuli TangAbstract:Abstract This paper presents the experimental and numerical investigations on the seismic behaviour of Steel-Jacket retrofitted reinforced concrete (SJRRC) columns with recycled aggregate concrete (RAC). An unstrengthened reinforced concrete (RC) column and nine SJRRC columns tested under lateral cyclic loading are reported. The experimental results manifest that by using the Steel-Jacket retrofitting approach with RAC, the initial stiffness, ultimate strength, deformation ductility and energy dissipation ability of the columns are improved significantly. The peak strengths of the SJRRC columns are about 1.86–3.44 times of the counterpart of the original RC column. The retrofitted columns also show ductile post-peak load behaviour with the ductility coefficients ranging between 4.05 and 7.93. As the applied axial compressive loads increase, the failure mode of the SJRRC specimens is transited gradually from tension-controlled failure to compression-controlled failure. The specimens failed in compression-controlled mode exhibit plumper hysteresis curves, better energy dissipation ability, and higher secant stiffness than those failed in tension-controlled mode. The specimen having 100% recycled coarse aggregate replacement ratio has slightly lower lateral strength and secant stiffness than the specimens with 0% or 50% recycled coarse aggregate replacement ratio, and shows more serious pinching effect on its hysteresis curve. The effects of the preload and pre-damage of original column could be unfavourable on the cyclic performance of retrofitted column. The finite element analyses are also performed to further investigate the lateral behaviour of SJRRC columns. The proposed finite element model is validated by a comparison with the experimental results. By using the developed finite element model, parameter studies are undertaken and indicate that the applied axial compressive load and the thickness of Steel Jacket are the dominant factors affecting the lateral performance of SJRRC column.
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axial compressive behaviour of Steel Jacket retrofitted rc columns with recycled aggregate concrete
Construction and Building Materials, 2017Co-Authors: Jia Cai, Qingju Che, Xinpei Liu, Hua XueAbstract:Abstract It is an effective solution to strengthen structural column by using Steel Jacket and infill concrete for reinforced concrete (RC) structure retrofitting. In this research, the recycled aggregate concrete (RAC) is adopted as an infill concrete instead of using the normal concrete, in order to reduce the carbon footprint of construction. Fifteen columns including twelve Steel-Jacket strengthened columns, one unstrengthened column and two concrete filled Steel tube (CFST) columns are tested to investigate the axial compressive behaviour of Steel-Jacket retrofitted RC columns with RAC. The variables among the tested specimens include the recycled coarse aggregate replacement ratio, RAC strength, Steel tube thickness and preload of original column. Experimental results illustrate that using Steel Jacketing approach for retrofitting could significantly improve the strength, stiffness and ductility of the columns. The axial compressive strength of the Steel-Jacket retrofitted column with RAC is slightly lower than the one with normal infill concrete, but the influence of recycled coarse aggregate replacement ratios is negligible. The peak strengths of Steel-Jacket retrofitted columns can be significantly enhanced by increasing the thickness of Steel tube. The performances of the Steel-Jacket retrofitted columns are similar to that of the CFST columns. The effect of the preload of original column on the ultimate strength of Steel-Jacket retrofitted column is limited. A finite element (FE) model is also developed by using ABAQUS software to simulate the performance of Steel-Jacket retrofitted columns. The accuracy of the model is validated through comparing with the experimental results. By using the developed FE model, the mechanical behaviour of the column is further discussed in details and extended parametric studies are undertaken to elucidate the effects of various influencing factors on the behaviour of the column and its components. The design methods for predicting the axial compressive strength of the retrofitted column with RAC are suggested.
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behaviour of Steel Jacket retrofitted rc columns with preload effects
Thin-walled Structures, 2016Co-Authors: Jia Cai, Qingju Che, Xinpei LiuAbstract:Abstract Steel Jacketing is an efficient way to retrofit reinforced concrete columns. Previous studies focused on the performance improvement without considering the preloads on the original columns. The preloads might inevitably affect the structural performance of the retrofitted columns. Comprehensive experimental and numerical studies on the behaviour of Steel-Jacket retrofitted RC columns with preload effects are presented in this paper. Twenty-nine Steel Jacketing columns with different Steel tube thicknesses, axial preloading levels and load eccentricities are tested under concentrically or eccentrically compressive loading. The experimental results are discussed and illustrate that the effects of preloading levels on the axial compression strength of the retrofitted columns are negligible while increasing the preloads could decrease the eccentric compressive strength. A fibre element model is developed to predict the behaviour of the retrofitted columns. The material non-linear behaviour of all the components considering the Steel tube and stirrup confining effects on the concrete as well as the preloading action are taken into account in the model. The model is validated by comparing its results with the experimental results. Extensive parametric studies are undertaken by using the proposed numerical model to elucidate the effects of axial and moment preloading and the effects of preloads with various other parameters on the performance of the retrofitted columns.
