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Lei Y.,Xiamen University | He M.-Y.,Xiamen University | Lin S.-Z.,Xiamen Construction and Management Bureau
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2013

Aseismic behavior of base-isolated structures is highly dependent on nonlinear properties of their rubber-bearing isolated system. Here, a data-based method using only partial measurements of structural dynamic response and excitation was proposed to identify the nonlinear property of the rubber-bearing isolated system without its mathematical model. Firstly, structural parameters including the linear stiffness and damping of the rubber-bearing under a minor earthquake were identified based on the extended Kalman estimator approach. Then, the nonlinear effect of the rubber-bearing was treated as an additional unknown fictitious loading exerted on the building under a severe earthquake. With sequential application of Kalman estimator method in the structural responses and the least-square estimation of the additional unknown fictitious loading, the nonlinear property of the rubber-bearing was identified. Numerical simulation results demonstrated that the proposed method is capable of identifying nonlinear property of a rubber-bearing isolated system with good accuracy. Source


Lei Y.,Xiamen University | Lei Y.,Tongji University | Wu D.-T.,Xiamen University | Lin S.-Z.,Xiamen Construction and Management Bureau
Engineering Structures | Year: 2013

Since some excitations such as earthquakes or wind forces cannot be accurately measured, it is necessary to explore algorithms which can integrate structural control and the identification of unknown excitations. In this paper, an algorithm is proposed for the decentralized structural control of tall shear-type buildings under unknown earthquake-induced ground motion. The equations of motion of a tall controlled shear building subject to unknown ground motion are established in the absolute co-ordinate system, in which the ground motion input is applied to the 1st floor of the building and treated as an unknown external excitation. A decentralized control algorithm based on the instantaneous optimal control scheme is developed with limited measurements of structural absolute acceleration responses. The inter-connection effect between adjacent substructures is treated as 'additional unknown disturbances' at substructural interfaces to each substructure. Instantaneous optimal control forces are obtained by sequentially utilizing a Kalman estimator for the substructural state vector and least square estimation of the 'additional unknown disturbances'. Then, unknown ground motion is subsequently estimated by the Newmark-β method. To validate the performances of the proposed algorithm, two numerical examples of decentralized control of tall building models under unknown earthquake excitations are studied and the simulation results are compared with those by the conventional centralized control under measured earthquake excitation. © 2013 Elsevier Ltd. Source


Lei Y.,Xiamen University | Lei Y.,Tongji University | He M.Y.,Xiamen University | Lai Z.L.,Rice University | Lin S.Z.,Xiamen Construction and Management Bureau
Science China Technological Sciences | Year: 2015

It is important to explore efficient algorithms for the identification of both structural parameters and unmeasured earthquake ground motion. Recently, the authors proposed an algorithm for the identification of shear-type buildings and unknown earthquake excitation. In this paper, it is extended to the investigation of the identification of flexible buildings with bending deformation and the unmeasured earthquake ground motion. In the absolute co-ordinate system, the unmeasured ground motion can be treated as an unknown translational force and a bending moment at the 1st floor level of a flexible building. Structural unknown parameters above the 1st story of the building can be identified by the extended Kalman estimator and the 1st story stiffness and the unmeasured ground motion are subsequently estimated based on the least-squares estimation. The proposed algorithm is further extended to the identification of tall bending-type buildings based on substructure approach. Inter-connection effect between sub-buildings is treated as ‘additional unknown inputs’ to sub-buildings, which are estimated by the extended Kalman estimator without the measurements of rotational responses. Numerical examples demonstrate the identification of a multi-story, tall bending-type building and its unmeasured earthquake ground motions using only partial measurements of structural absolute responses. © 2015, Science China Press and Springer-Verlag Berlin Heidelberg. Source


Lei Y.,Xiamen University | Lei Y.,Tongji University | Li T.,Xiamen University | Zhang J.-G.,Xiamen University | Lin S.-Z.,Xiamen Construction and Management Bureau
Gongcheng Lixue/Engineering Mechanics | Year: 2014

Based on observed data of typhoons in Xiamen region during 1959- 2008, numerical simulation of typhoon is conducted using the Yan Meng wind-field model to obtain the extreme wind velocity series. Then, extreme wind velocity for different return periods is estimated and compared with the statistical results of the observed data of annual extreme wind velocity in Xiamen region, as well as the current structural code, to provide more accurate wind load information for the wind-resistant structural design. Furthermore, the effect of wind direction on extreme wind velocity is discussed in this paper to provide theoretical guidance of choosing appropriate building direction. Finally, gradient wind level as well as typhoon-governed wind profile in Xiamen region is proposed based on numerical simulation of the Yan Meng typhoon wind-field model. Source


Lei Y.,Xiamen University | Lei Y.,Tongji University | He M.,Xiamen University | Liu C.,Xiamen University | Lin S.-Z.,Xiamen Construction and Management Bureau
Advances in Structural Engineering | Year: 2013

Due to the fact that some structural external excitations such as earthquakes and wind forces can not be accurately measured under actual operating conditions, it is necessary to investigate algorithms for structural identification under unknown earthquakes. In this paper, an algorithm based on the extended Kalman estimator approach is proposed for the identification of structural parameters and unknown excitation of tall shear-type buildings with only partial measurements of structural absolute acceleration responses. The equation of motion of a tall shear building under ground motion is established in the absolute co-ordinate system, in which the ground-motion input is applied to the 1st floor of the building as an unknown excitation. Based on substructure approach, the tall building is decomposed into substructures. For each substructure above the 1st floor, substructural relative responses and parameters are identified by extended Kalman estimator. For the substructure containing the 1st floor, it is proposed that substructural extended state vector is firstly identified by the extended Kalman estimator and the unknown excitation is subsequently estimated by least-squares estimation. Then, the 1st story stiffness is estimated based on structural eigenvalue equation and the expansion of the determinate of the structural eigen-matrix. The unknown ground motion is identified by the Newmark-β method. A numerical simulation example demonstrates the efficiency of the proposed algorithm. Source

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