25 November 2011, Volume 30 Issue 11
    

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  • Wu Zhi-qiang;Hao Ying;Guo Kai
    . 2011, 30(11): 1-3.
    Abstract ( 902 ) Download PDF ( 508 )   Knowledge map   Save
    Nonlinear vibrations of a single-degree-freedom system involving hysteresis with two loops are investigated. Firstly the frequency response equation is derived for system under primary resonance by applying the averaging method. Secondly the effects of the excitation amplitude are studied. It is found that there are four types of frequency response for different levels of the excitation. It is also revealed and verified by numerical simulation that only one type is suitable for vibration reduction design.
  • Hao Hui-rong;Bai Hong-bai;Li Dong-wei;Liu Shu-feng
    . 2011, 30(11): 4-7,35.
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    Experiment modeling is an effective means to find out the essence of physical phenomenon. To 6-DOF active-passive vibration isolation platform, experiment modeling is the premise to make vibration isolation be active-controlled and also the key to gain satisfying control result. Conditions of sensors’ arrangement are presented by deriving the coordinate change from physical space to sensor space. Combining with the transcendental thesis of 6-DOF active-passive vibration isolation platform and the signal obtained from tests, the dynamic model of actuator-sensor is build up using least square estimation recurrence algorithm.
  • Huang Qian;Zang Feng-gang;Zhang Yi-xiong;Cai Feng-chun;Ye Xian-hui
    . 2011, 30(11): 8-12.
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    By introducing the hysteretic forces acting on the pipe into Hamilton’s principle through the principle of virtual work, the nonlinear equations of motion of cantilevered pipes conveying fluid with hysteretic supports are derived. Galerkin’s discretization method is applied to the motion equations, numerical simulation of dynamic responses are performed based on the platform of MATLAB, First,the reasonableness of the hysteretic model has been proved by comparing the results of its degenerate model and the results by other researchers. Then, numerical simulations of dynamic response of system and parametric researches about structural nondimensional stiffness are conducted. Results show abundant dynamic phenomenon of the system, the variety of nondimensional stiffness can lead to the changes of bifurcation style, bifurcation path, period number and parameter range.
  • Yang Zhi-chun;Zhang Mu-yu;Wang Le
    . 2011, 30(11): 13-16.
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    An approach to detect structural damage using auto correlation function is proposed. The normalization of the auto correlation function of the acceleration response at time zero is theoretically proved only depended on the modal parameters of the structure, which is used to get the damage index to locate the damage. The feasibility and the effectiveness of the proposed method are verified by damage detection experiments of the fastener loosening of aircraft stiffened panel under white noise excitation. The results of the damage detection experiments also show that the proposed method, which only the acceleration response is needed, is suitable for real time detection of the fastener loosening.
  • Bai Zheng-feng;Zhao Yang;Zhao Zhi-gang
    . 2011, 30(11): 17-20,4.
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    In order to study the dynamic characteristic of mechanism with joint clearance, an improved hybrid contact model in the joint clearance is established. The friction effect is considered by using improved Coulomb friction model. Then the hybrid contact model in joint clearance is incorporated into ADAMS. For the crank follower mechanism, the dynamic model of mechanism with joint clearance is established and the dynamic simulation is carried out. The simulation results can predict the effects of clearance on the mechanism dynamic characteristic preferably, and which is the basis of mechanism design. The contact hybrid model for clearance in this paper develops the contact modeling of clearance and dynamic characteristics analysis of mechanism with joint clearance, and it is useful for engineering application.
  • Du Yong-feng;;Zhu Qian-kun;Li Hui
    . 2011, 30(11): 21-24.
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    According to horizontal stiffness of laminated rubber bearing serially connected with column, which concerned engineering field, the horizontal stiffness formula was established and compressive stress influence on horizontal stiffness and dynamic response of isolated structure were investigated. First, field matrix of single laminated rubber bearing was established. Secondly, field matrix of the laminated rubber bearing serially connected with column, the relation between internal force and displacement at arbitrary cross sections and state variable at end of laminated rubber bearing serially connected with column, the horizontal stiffness formula based on transfer matrix method were derived, avoiding tedious mechanical derivation. Finally, compressive stress influence on horizontal stiffness and seismic response of isolated structure were investigated. The results shows that the horizontal stiffness decrease with the rise of the compressive stress, laminated rubber bearings fixed in foundation should be adopted in near fault area.
  • Yang Li-zhi;Yang Xue-shan;Chi Qing-lei;Wang Nan
    . 2011, 30(11): 25-29.
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    Introduced the principle and technical performance of vibration sensor with double outputs, that based on big damping ratio. By using the electric capacity sensing and the big damping ratio moving coil sensing technology, acceleration and velocity could be measured simultaneously with an vibration sensor. The bandwidth and range of the vibration sensor are expanded by using big damping ratio moving coil technology. The paper give the system equation, get the frequency characteristic and sensitivity of acceleration and velocity. As a new instrument for engineering vibration measurement, the sensor could be used in low and ultra low frequency vibration measurement for Civil and Hydraulic Engineering and strong gound motion.
  • Peng Gang;Feng Jia-chen;Liu Yuan-dong;Wang Dan-yong;Wang Xu-cai
    . 2011, 30(11): 30-35.
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    The “bar-tube” type punch shear experimental technique was modified and optimized according to the analysis of punch shear technique of Hopkinson bar, and aimed at material performance and applied characteristics of fiber reinforced composite laminates. Some technical problems have been resolved,such as the vibration of in-put bar, coaxial adjustment between the in-put bar and out-put tube, large dispersion of the test results, and so on. The confined dimensions of the in-put bar ,and the composite sample, and the out-bar were established based on the match analysis of them in the dynamic punch shear experiments. The effect of the clearance between bar and tube on the punch shear properties have been investigated by finite element analysis, research suggests 0.2mm~0.3mm clearance designing is appropriate to 2mm~4mm laminate sample against Ф14.5mm in-put bar punch shear test . Experimental data show that loading rates have a remarkable effect on the shear properties of glass fiber reinforced composite laminates.
  • Zhang Li-tao;Li Zhao-xia;Zhang Yu-feng;Fei Qing-guo
    . 2011, 30(11): 36-41.
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    A method of model validation is carried out according to accuracy of the model with identification parameters describing the structure to be identified. Identification parameters are usually not selected appropriately, however, due to the absent knowledge of the structure and to the improvements on calculation efficiency. Therefore, there is always inconsistency between the model and the structure and, when it is rather obvious, the traditional method of model validation often fails. In order to deal with the problem, a L-curve based method of model validation was proposed. The method not only exploited the condition that regularization techniques may be adopted to improve the ill-posedness of solutions of structural identification, but also applied the correlation between objective functions of identification results and norms of as a priori knowledge. As it was carried out according to the rules summarized in numerical calculations, the proposed method was expected to improve the above disadvantage of the traditional one. Validation of the given models was carried out using the L-curve based method with one spring-mass system and BENCHMARK structure as numerical and experimental examples respectively. The results showed that the traditional method could not find the best model among the obtained ones in the experimental example while the proposed method could pick out the best one in both the numerical and experimental example, which proved the validity of the proposed L-curve based method of model validation.
  • Lu Zhao-Gang;Hao Zhi-Yong;Zheng Xu
    . 2011, 30(11): 42-45,5.
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    The indirect coupling loss factor between two flexible bodies indirect coupled through a rigid body was calculated from the energy conversation equation, in which the energy of each subsystems was accounted through the Finite Element Energy Flow model excited by the random wide-band excitation. The energy of each subsystem should be space and frequency averaged. Compared with the traditional Finite Element Method, the new procedure in this paper was efficient in computation time; and was reliable compared with the traditional SEA Model. Last, the method was verified though the experiment.
  • Cai Yan-ping;Li Ai-hua;Shi Lin-suo;He Yan-ping;Zhao Jing-ru
    . 2011, 30(11): 46-52.
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    The end effect of empiricd mode decomposition (EMD)that appears when using spline interpolation to get two envelops of the data is discussed. The shortage of ordinary end extending methods is analyzed. An extending method based on lyapunov exponent forecasting mode is proposed. Analyzing the shortages and problems of Lyapunov exponent forecasting model, then a new forecasting model based on local radiation degrees which is similar to Lyapunov exponent forecasting model is proposed. By using the improved lyapunov exponent forecasting mode, the data sequence is extended by adding some predicted points, and it is stopped when a new local maximum and minimum points are emerged. Then the EMD could be decomposed exactly. By comparing the proposed method with the other ordinary end extending methods, it can be find that the proposed method is effective when dealing with the end effect. In the end, the proposed method is used in the fault diagnosis of rotary machine, the result demonstrates that end effect can be controled effectively and faults can be recognized exactly by using the proposed method.
  • Zhang Zi-yang;Xie Shou-sheng;Qian Zheng-wen;Long Men;Peng Jing-bo
    . 2011, 30(11): 53-56.
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    This paper presents a method to update the FE(finite element) modal of high pressure spool in aero engine. Having analyzed the mechanical modals which described the contacting surfaces between the wheel disks in rod fasten rotor, it remodeled the contacting surface of FE modal of high pressure spool. By using a fusion method which combines the modification of stiffness of the spring and FE modal together, it develops a total optimization modal for FE modal stiffness updating which concerns contacting surface. Furthermore, it employs the straighten algorithm to extract the parameters which need to be calibrated in the calculation of the optimization modal, and modifies them with modal parameters got by experimental modal analysis. Results of an experimental application of this fusion modification are given to illustrate that the modified FE modal truly represents the contacting state of high pressure spool.
  • Xu Lue-qin;Li Jian-zhong
    . 2011, 30(11): 57-61,9.
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    In combination with Daxie Bridge in Ningbo, effect of side retainers on the lateral anti-seismic system for a cable-stayed bridge is investigated. Nonlinear time history analysis method is utilized to obtain the seismic response of Daxie Bridge in correspondence with three conditions, i.e. structural response excluding retainer influences, structural response incorporating retainer influences, and structural response considering the effects of damage of the retainers. It is found that the pounding effects between girder and retainer are effective to reduce the earthquake response of the auxiliary piers, which usually governs the design of cable-stayed bridges in the transverse direction. Damage of retainers will amplify the lateral displacement of the girder, which is not expected to happen for cable-stayed bridges. It is efficient to diminish the seismic response of bridge structure, to restrain the displacement of girder and to protect the bearings from earthquake when dampers are mounted on the side piers, which will, however, increase the cost and cause design problems. Recommendations are made to choose strong retainers with sufficient strength to survive severe ground motions as a useful measure for the cable-stayed bridge.
  • Guo Meng;Yao Qian-feng;Huang Wei;Zhang Xu-feng;Li Peng-fei
    . 2011, 30(11): 62-66.
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    Multi-grid composite wall-shear wall structure is a new type resistant structure consisting of composite walls and shear-walls which can effectively solve some disadvantageous problems about multi-grid structure, such as building height and application range were constrained in highly seismic area. Displacement calculating method for the structure subjected to horizontal loads was proposed. Based on Timoshenko beam theory, the composite wall was treated as shear-flexural type cantilever wall, and the displacement differential equation was established by the continuous approach, then the deformation analytical solutions were derived. The examples show that frame-shear structure can be regarded as one of special forms of composite wall-shear wall structure, and the whole lateral displacement curve of the structure express shear-flexural type characteristic which shear deformation should not be ignored. The findings provide a theoretical fundamental to study and internal force calculating method anti-seismic design further.
  • Ren Xiao-hu;Huo Jing-si;Chen Bai-sheng
    . 2011, 30(11): 67-73,8.
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    Drop weight setup was used to experimentally study the impact resistance of concrete-filled steel tube (CFT) after exposures to high temperature. The influences of the high-temperature, impact velocity, impact energy, steel ratio and axial load level on the impact resistance of CFT under fire exposure are discussed. The stress-strain relation, the force and compressive deformation versus time history relations of the tested specimens were recorded to analyze the impact behaviors of CFT columns after exposure to high temperature. The test results show that the influences of the high-temperature, impact velocity, impact energy, steel ratio have remarkable effects on the dynamic behaviors of CFT columns after exposure to high temperature, but the influences of axial load level is not remarkable. The compressive deformations and residual deformations would increase obviously with increasing the high-temperature and impact velocity, axial load level, but decrease with increasing the steel ratio. Although the CFT specimens after exposure to high temperature suffered remarkable compressive deformations, the ductility of CFT decreased, the composite columns still remained in good integrity. The test results show that CFT after exposure to high temperature has an excellent impact-resistance.
  • Dong De-yi;;Xin Hong-wei;Yang Li-Wei;Li Zhi-lai;Guan Ying-Jun
    . 2011, 30(11): 74-78.
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    As its stress is usually very high during random vibration, which leads to remained strain causing decrease of imaging quality, random vibration response of large aperture mirror component was analyzed. The theory of random vibration analysis and its finite element implementation were discussed. According to its design feature and stress transfer path, the mirror component’s finite element model was built and its random response was analyzed. The root mean square (RMS) acceleration and cumulative mean square (CMS) stress were obtained. Analysis shows that the RMS acceleration of the mirror is 16.3Grms and the RMS stress of the flexible support is 34.9MPa. Meanwhile, random vibration test was done for verification. Test shows that the mirror’s RMS acceleration is 16.3Grms and the flexible support’s RMS stress is 30.3MPa, indicating the error of 1.8% and 13.2% respectively, which satisfies the accuracy requirements and verifies the validity of presented numerical method.
  • Cao Jia-liang;Shi Wei-xing;Wang Yang;
    . 2011, 30(11): 79-84.
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    Applicability of response spectra was investigated based on study of damping reduction factors and pseudo relative displacement spectra of ‘Code for seismic design of buildings' (GB 50011). On the basis of damping mechanism, it is found that except for reducing relative displacement spectra value effectively, the higher damping ratio may also amplify the absolute acceleration spectra value of building structures, rather than attenuate it all the time. In this case, comparison of seismic influence coefficient curves, damping reduction factors and pseudo relative displacement spectra varying from different site classes and damping ratios between Code (GB 50011-2010) and Code (GB 50011-2001) were performed. Besides, problems which should be noticed during the process of generating artificial seismic wave as input of time-history analysis of long-period structures with high damping ratio such as seismic-isolation structures or seismic-energy-dissipating structures were pointed out.
  • Du Hong-mian;Zu Jing;Ma Tie-hua;Ma You-chun
    . 2011, 30(11): 85-89.
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    Pencil probe, Blunt cylinder mount, and skimmer plate are transducer mounts commonly used for free-field overpressure measurement. Three mounts were calibrated with shock tube. The system function of different mounts and their response of shock wave were established and simulated by MATLAB. The result of calibration and simulation has been validated in large warhead explosion tests .The conclusion is got: the calibration method for free-field transducers with shock tube is feasible; the overpressure overshoot of blunt cylinder mount is the largest and its curve is some distorted; the overpressure overshoot of skimmer plate is smallest. The explosive blast measurement was done in which the sensors were higher than detonator. when the angle between transducer surface and shock wave propagation direction is negative, The overpressure peak of Blunt cylinder mount becomes the smallest than side on, but bigger than fact; the overpressure peak of Blunt cylinder mount is the biggest than side-on; skimmer plate causes significant error. The advice was given to choose mounts in overpressure measurement.
  • Yang Zhi-chun;Sun Hao
    . 2011, 30(11): 90-94.
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    It is known that the polarity of PZT transducer is determined by its strain state induced by the target structure under different mode. In building the piezoelectric shunt damping system, multiple piezoelectric elements must be connected properly so as to obtain an integral voltage source, and then connected with the shunt circuit. For this purpose, some typical topological structures of the electric network of the piezoelectric shunt damping system are proposed firstly. A critical analysis on the advantages and disadvantages of these networks in practical application is accomplished, based on the analysis the parallel connection is selected as the best configuration. According to the phase difference among different piezoelectric elements under this connection, a module of modal adaptation and phase shifting system is designe and built. With this module, the shunt circuit can follow the vibration modes of the structure and regulate the phases of output voltages of piezoelectric elements and make them synchronized automatically. By means of the concept of modal adaptation and phase shifting, we can avoid the neutralization of induced charges on polarized surfaces of different PZT transducers.
  • . 2011, 30(11): 95-100.
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    A theoretical model for free vibration of orthotropic truncated conical shell with fluid load is presented. The solution for free vibration of truncated conical shell with fluid load is found by use of wave propagation approach and Galerkin method. The fluid loaded conical shell is divided into several segments and each small strip of conical shell is treated as circular cylindrical shell. The fluid load of conical shell is obtained by determining the fluid load of each cylinder. Thus, the fluid load acts on conical shell by parts. Numerical results for isotropic and orthotropic conical shells with fluid load or without fluid load are computed to illustrate the validity of the presented solution procedures.
  • Yan Bo;Chen Ke-quan;Zu Zhen-ghua;Zhang Hong-yan;Zhou Song
    . 2011, 30(11): 101-105.
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    Numerical model of an iced quad-bundled conductor line with new intelligent de-icing equipments is set up by means of ABAQUS software, and simulation method of the de-icing process is numerically carried out. The feasibility of the intelligent de-icing method is verified based on the numerical simulation. Tension failure criterion is employed in the simulation of the failure of the ice, and the user material subroutine VUMAT of ABAQUS software is developed to introduce the constitutive relation of the ice and the deletion of the broken ice elements. Several de-icing scenarios are numerically studied with the variables including opening displacement of the de-icing equipment, the number of installed de-icing equipments on the line and the thickness of the ice covered on the conductors. The obtained numerical results provide a reference for the design and realization of the intelligent de-icing equipment.
  • Li Lei;Haoji-ping;Li Guang-hui;Huang Yi
    . 2011, 30(11): 106-111,.
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    Based on theory of Lematire。s equivalent strain of the damage and with damage of bars of the shallow reticulated spherical shell, nonlinear dynamical equations of the shallow reticulated spherical shell with damage is given by the quasi-shell method. The method of perturbation-variation selected maximal amplitude in the center of the shallow reticulated spherical shell as the perturbation parameter is given. Then the nonlinear vibration equation of the system with damage under the boundary conditions of fixed and clamped is solved by perturbation-variation and the eigen-relation is obtained. And nonlinear dynamical equations of the shallow reticulated spherical shell with damage are given by the quasi-shell method and the Galerkin method. an accurate solution to the free oscillation of the shallow reticulated shells with damage is solved. So theoretical critical condition of chaos motion is given by the Melnikov function method. The chaos motions of the shallow reticulated spherical shells with damage are simulated numerically by computer numerical emulation under nonlinear forced vibration and it is founded that the damage makes easily the system occur the chaos motion.
  • Yu Shang-jiang;Chen Xian;Yang Ji-xaing
    . 2011, 30(11): 112-116.
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    In order to .measure the dynamic strain in concrete during impact or explosive test, a fiber Bragg grating (FBG) sensor special designed for inner strain measurement in concrete was developed. The concrete specimens in which the FBG sensors were embedded were prepared and tested under impact in split Hopkinson pressure bar (SHPB). The inner and surface strains were measured by FBG sensors and strain gauges separately and an attempt to construct the dynamic relationship between stress and strain with the data was made. The analyses to the results show that the method of strain measurement in concrete with embedded FBG sensors is feasible and more reasonable if accurate strains and exact performance of concrete are demanded. The FBG sensors were proved to be suitable for dynamic strain measurement in concrete and can be widely used in concrete and rock during their dynamic performance tests and response measurement under impact or explosive loads.
  • Li Xia;Sun Lu-zhong;Yin Hong-bo;Xie Xing-kun
    . 2011, 30(11): 117-121.
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    In order to investigate the property of flexible overhead trestle bridge, the detached eddy simulation method is employed to simulate turbulence, and ALE (Arbitrary Lagrangian Eulerian) method is adopted to solve fluid structure interaction. The 3D displacement responding process of trestle bridge system subjected to wind and wave is simulated. Results show that the angular movement of trestle bridge is very small and can be ignored. The traditional simple superposition method, which used to compute displacement response of trestle bridge, may lead to big error. If wave frequency is close to trestle bridge’s natural frequency, strong sympathetic vibration will be induced and the displacement response of trestle bridge subjected to coupling of the two loads is much bigger than only to wave load. In contrast, if wave frequency is quite different from trestle bridge’s natural frequency, then the linear displacement response subjected to the couple of the two loads is smaller than summation of response to the two single loads, but the amplitude of angular displacement response is almost the same considering coupling of air and wave or not.
  • Cao Mei-gen;Zhou Fu-lin;Tan Ping;Fan Rong-quan;Lu Zhi-cheng;Zhang Xue-song
    . 2011, 30(11): 122-129.
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    Earthquake damage experience at home and abroad shows that seismic performance of power transformer and the bushings is weak subjected to intensity earthquake as 5.12 Wenchuan great earthquake. At present, study on seismic performance of transformer and bushing by using shaking table test simulated earthquake is the most accurate and most advanced means. Consulting Chinese current transformer structure characteristic, one transformer experiment model are design. Actual porcelain bushing of 220 kV and 500 kV was mounted on the experiment model. Firstly, One new three grade guidelines about transformer seismic fortification are put forward. Secondly, dynamic characteristic on transformer and the bushing are tested by inputting white noise. Lastly, shaking table test simulated earthquake are developed by x-dir. or x-direction inputting actual seismographic record, artificial waves and resonant beat-wave seismic waves, etc. Seismic response time history curve and data of the key position for acceleration, displacement and strain were acquired. The seismic response regularity and characteristic are further found by analyzing a great deal of datum on seismic response of transformer and bushings. Certainly, The above testing and researchhave a great reference significance for the amendment of related seismic norms and improving and enhancing the seismic capacity and design of transformer-bushing system.
  • Yu Mei;Liu Ai-dong;Ma Ming-de;Yang Li-feng;Zuo Ai-bin;Hu Hong-bo
    . 2011, 30(11): 130-134.
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    Based on urgent needs for quantity traceability of ultra-low frequency vibration measuring instruments on research fields such as Structural Dynamics, Geophysics and Seismic Geophysical Prospecting etc., the ultra- low frequency (~0.002Hz) and large amplitude (1mp-p) laser interferometry vibration magnitude and phase measurement technology is researched. According to the fact that the tracking measurement capability of laser interferometry will deteriorate in the case of the dynamic ultra-low frequency and large amplitude, the homodyne quadrature laser interferometer with DC output characteristic is developed. To solve the key technical problem of the difficulty to collect and process data,because of the enormous data in the range of ultra-low frequency, Self-adaptive Dynamic Decomposition Algorithm is presented. Experimental data of the quartzose flexible accelerometer is given. The results show that this measuring system can accurately measure the magnitude and phase of acceleration with laser interferometry in the frequency range of 0.002Hz~2kHz and the dynamic optical path of more than 1m.
  • Ji Gang;Zhou Qi-dou;Xie Jian-bo
    . 2011, 30(11): 135-141,.
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    To predict the dynamic response and acoustic radiation from an underwater structure, large impedance method is provided based on finite elemnt/ boundary element method, which uses the vibration data got from experiment as input. To use large impedance method, an imaginary element with large impedance should be loaded at the test point. A force should be driven on the test point, which leads to the same vibration response at the test point as is tested. The imaginary element may be large mass or large grounded spring, which is chosen according to the item tested at the test point. Since the dynamic response is effected only by the response of the test point, the impedance of the main structure and the transfer impedance from the test point to the main structure, the driven equiment which is on the upstream of the test point needn’t be built in the finite element model, which leads to great convinience in prediciton of dynamic response and acoustic radiation from an underwater structure. Dynamic response and acoustic radiation from a steel cylindrical model is predicted using large impedance method. Comparisons of numerical results and experimental results show good agreement. Large impedance method is validated as useful for predicting dynamic response and acoustic radiation from an underwater structure using the vibration data got from expeiment as exciting input.
  • Zhou Xiang-yang;;Zhang Lue-qiu;Zhou Lei-jing;Liang Shu-guo ;Zou Yao
    . 2011, 30(11): 142-147.
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    Rigid models were designed based on Taishan nuclear power plant to investigate wind pressure distribution and wind-induced dynamic response of main powerhouse structure of conventional island in a third generation nuclear power plant. Fluctuating wind pressure was tested under the turbulent flow in a boundary layer wind tunnel considering the interference effects of neighboring nuclear island and adjacent structure. The characteristics of mean, fluctuating and peak pressure coefficients on the structure were analyzed. A calculation procedure was developed for evaluating the wind-induced dynamic response by using frequency-domain method. The equivalent static wind loads and wind load factor were obtained based on optimization theory and the critical wind angles were determined. The calculation and analysis above can supply a reliable guide for safety evaluation of wind resistance.
  • Zhao Gui-feng;Ma yu-hong
    . 2011, 30(11): 148-152.
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    In this paper, for the slide-limited friction base isolation technology, the total restoring force model of the isolation device is given, the motion equation of the isolation system is established, and the nonlinear analysis program is worked out. The influence factors such as friction coefficient, elastic stiffness and yield displacement of the displacement-constraint device on the base isolation system are analyzed in detail, and based on a great deal of analysis, the rational range of the parameters are given, which can provide reference for design and application of the friction base isolation system.
  • Liu Zhi-wen;Zhou Shuai;Chen Zheng-qing
    . 2011, 30(11): 153-156,.
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    Numerical simulations of Vortex-induced vibration (VIV) of rectangular cylinder with aspect ratio 4 were conducted with the dynamic mesh in present paper. The two-dimensional Reynolds-averaged Navier-Stokes (RANS) code equipped with the SST turbulence model was applied to solve the N-S equations of incompressible viscous fluid. The equation of structural vibration was solved by Newmark- integration method which was embedded in Fluent with user defined functions (UDFs). The results show that the lock-in region and VIV amplitudes of the rectangular cylinder are agree well with the wind tunnel experimental results which have been published. And it is feasible to conduct the numerical simulation of VIV of bluff section with separation and reattachment phenomenon with the present method.
  • Luo Song-nan;Song Jun-han;Feng Xin
    . 2011, 30(11): 157-160.
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    Considering the influence of the large deformation, the non-linear dynamic equations of high pier under the foundation Perpendicular motion by earthquake are established. By supposing the displacement shape function and applying the Galerkin method, the dynamic equations about time are gained. By processing numerical calculation, the displacement response curves of the high pier under the foundation Perpendicular motion by earthquake with different magnitude and the overall process from the transverse vibration to the instability of the high pier are given. The critical seismic acceleration and the instability time are obtained. The influence of the different seismic peak, the slenderness ratio and the weight of the bridge on the displacement response, the critical seismic acceleration and the instability time are analyzed.
  • Lin Li;Zhang Xu;Li Yun;Cheng Guang-xu
    . 2011, 30(11): 161-164,.
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    The pressure response functions and the corresponding four-pole parameters of two-dimensional rectangular and cylindrical mufflers have been obtained by modal expansion methods. Thus, transmission loss (TL) calculation model of different shape mufflers has been derived. In order to verify the present calculation model, the TL results of a two-dimensional cylindrical muffler obtained by the proposed model has been verified by comparing with that obtained by the three-dimensional finite element method. It is demonstrated that the proposed model is more computationally efficient than the finite element method with adequate computational accuracy. This model is more accurate if the area of the surface source is comparatively large, compared with the TL results by Green’s function method.
  • Gao Feng;Zhao Feng-bing
    . 2011, 30(11): 165-170.
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    For the problem of the static-dynamic analysis in underground structure considering both static and dynamic effect, the transformation of artificial boundaries from the static analysis to the dynamic analysis had great effect on the dynamic calculation result. Through the analysis of boundaries transformation principles in transformation methods, it was indicated that, while making the dynamic analysis with the initial condition of the stress fields gotten in the static analysis, putting on the loads and the boundary condition that induced the stress fields at the time of inputting the static stress fields could make the modal in a state of static equilibrium at time zero of the dynamic analysis; and applying the constraint reaction forces at the time of deleting the constraint boundaries had the same effect. A method of applying no dynamic load in the dynamic analysis was given to check the error of the artificial boundaries transformation methods in the static-dynamic analysis. The calculation results indicated that, when the unified viscous-spring boundary for static and dynamic analysis and its corresponding calculating methods were applied in static-dynamic analysis of the underground structure, this boundary resulted in big error in the static calculation of some underground cases. On the base, a more rational transformation method of artificial boundaries for the static-dynamic analysis of underground structure was recommended. In the method, the static constraint would be deleted firstly in the transformation of artificial boundaries; and all the loads, the static fields and the constraint reaction would be brought in the modal while applying the dynamic artificial boundaries before the dynamic analysis. The accuracy of the method was checked through the analysis of the calculation results of a engineering case.
  • Zhou Yu-rong;He Zheng-you
    . 2011, 30(11): 171-174.
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    The phenomenon of stochastic resonance (SR) in a linear system subject to bias signal-modulated noise and additive noise is investigated. By the use of the linear system theory, we get the exact expression of the output signal-to-noise ratio (SNR). It is shown that the SNR is a non-monotonous function of the system attenuation parameter, of the signal bias, as well as of the intensities of the signal-modulated noise and the additive noise. In addition, the SNR behaves non-monotonically with the increase of the correlated strength between the two noises
  • Gu Pei-ying;;Deng Chang;Tang Lei;
    . 2011, 30(11): 175-178.
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    Operational strain mode shape (OSMS), direct index methods of damage location detection (named as ) and damage degree detection (named as ) are introduced in the paper. The methods were advanced in recent years by author. Then, the results of model test and numerical simulation are applied to verify the methods. The results show that the operational strain mode shape is similar to the strain mode shape under impact excitation. According to the results, direct index methods of damage location detection and damage degree detection are also improved. The direct index value of damage location detection at damage location is greater than the index value at undamage location, and, the damage location detected is in accord with actual damage location. Furthermore, when damage degree is equal, the variation of is slight. The value of is independent of damage location, order number of strain mode shape and normalization. If the space between of damages is longer than length affected, the methods can be applied to the multi-damage detection of structure.
  • Yu Hu;Hou hong;Yang Dai
    . 2011, 30(11): 179-182.
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    For the purpose of reducing noise from the vibration of range hood’s shell, the
    vibration response of it is calculated based on the finite element model of range hood’s shell when
    excited by the motor. Then, the optimal geometric design of the structure is preformed using the
    peak particle velocity at four sensitive nodes as the objective function during which the
    thicknesses of the four parts are adopted as the designing variable. In addition, the weight of the
    structure is kept no more than its original weight. The particle velocity is calculated by using the
    commercial software Nastran and the DOE method is utilized to obtain the optimized shell
    thickness. After which, the particle velocity peak of the designed area is decreased more or less
    and a maximum 8.2 dB reduction of vibration velocity level can be obtained. Results show that the
    changes of the four part’s thicknesses can reduce the radiating noise of the range hood at the
    condition of no increase of the shell’s weight.
  • Du Xiang-hua;Zhu Hai-chao;Mao Rong-fu
    . 2011, 30(11): 183-185,.
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    When sound radiation modes are used to calculate sound radiation power, complicated coupling items between vibration modes can be eliminated. Deign variables may be classified as three categories in structure-acoustic sensitivity analysis. Only one or two categories design variables have been studied previously. In this paper, acoustic sensitivity of all types design variables was studied using sound radiation modes method. The simulation on a spherical sound radiation model has proved that the method is effective.
  • Zhou Ying;Lu Xi-lin;Zhang Cui-qiang
    . 2011, 30(11): 186-189.
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    With the increase of the building height, how to design super-tall buildings with good earthquake resistance draws extensive attention of engineers. In super-tall buildings, the structural form with central core tubes and peripheral frames is one of the popular systems. Outriggers are usually set between the tubes and frames to coordinate the internal forces and structural deformation. Targeted on a 240-meter super-tall building, this paper analyzed the seismic performance of the structure without outriggers, with one set of outrigger, and two sets of outriggers. Then viscous dampers were introduced to the outriggers where the structural stiffness and relative displacement is large. The seismic performance of the tall building with five types of dampered outriggers was analyzed. The conclusions drew in the paper will form the foundation for the future research on dampered outriggers in the super-tall buildings.
  • Pei Xing-zhu;Wang Ling
    . 2011, 30(11): 190-197.
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    This paper puts forward a kind of mega-suspended frame composite support system with damper.The stem department model of this system is simplified as the particle system model ,each layer of the lateral stiffness is deduced by elastic-plastic static method through SAP2000 software and the rationality of the simplification is discussed by SAP2000 software and a self-designed procedure. Based on these,to discuss the elastic-plastic seismic response analysis with three seismic waves through the self-compiling program and it is shown that along with the increase of resist lateral stiffness of the system, deformation energy consumption of the system reduces and the seismic energy consumption by damping increases,but the seismic energy consumption is constituted by deformation energy consumption , while for the mega-suspended braced and prestressed frame with damper, the main structure's horizontal displacement and the differences between main and substructure can be reduced effectively by the viscous damper which can also avoid the collisions and protect the main structure.
  • Huo Lin-sheng;Li Hong-nan;Liu Meng
    . 2011, 30(11): 198-202.
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    The control effects of liquid dampers to eccentric structures and the correctness of theoretical analysis are experimentally studied through shaking table tests in this paper. A steel model of building with eccentricity only in one direction was designed. One tuned liquid column damper and circular tuned liquid column damper with optimized parameters were placed on the top story of the experimental model. The building mode with and without liquid dampers were vibrated on the shake table. The acceleration and displacement responses of the structure excited by earthquake records were analyzed. The results show that the liquid dampers can effectively suppress the torsionally coupled responses of eccentric buildings and the control effects for the structure with TLCD and CTLCD are better than the one with only TLCD or CTLCD.
  • Zhou Yun ;Wang Da-yang ;Li Qing-xiang
    . 2011, 30(11): 203-209.
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    Performance-based design idea has been a interesting topic in the design of engineering structures. The aim of this paper is to apply the method in wind-induced analysis of a high-rise building and realize performance objectives by using vibration control technology. The expected performance objectives of the building were proposed firstly. To realize the expected objectives, two kinds of numerical models were built by both ADINA and Etabs platforms and plans of double diagonal damper braces were presented. Then, performance analysis of the structure with and without dampers was investigated in detail. Results show that good agreement is obtained for the computational results between ADINA and Etabs. In excitations of middle and strong wind pressure, the expected performance objectives can not be satisfied for cases without dampers. However, the expected objectives can be well realized for cases with dampers in all wind pressure levels. So, structural dynamic performance in wind-induced vibration can be improved effectively by vibration control technology, such as viscous damper control, which provides a reliable way of realizing the performance-based idea in structural wind-resistant design. Results of this paper provide reference in a certain extent for structural design of using the performance-based design idea
  • Cao Wan-lin;Zhou Zhong-yi;;Wang Qing;Dong Hong-ying;Zhang Jian-wei
    . 2011, 30(11): 209-213.
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    A new kind of base vibration isolation masonry structure and an anti-seismic masonry structure were presented to improve the anti-seismic and damping performance of masonry buildings in rural areas. The two technologies have obtained the China national invention patent. Four rural housing structures were tested on shaking table. The test model includes: one base vibration isolation masonry structure model and its comparison model with anti-seismic technology measures, one special-shaped insulating concrete block with constructional columns masonry structure model and its comparison model made with normal concrete block and the corresponding constructional measures. Based on the experiment, the work performance of the base vibration isolation was studied; the anti-collapse capacity and wall failure process of the new anti-seismic structure were analyzed. The seismic design recommendations based on the above analysis were put forward. Experiments show that: the proposed base isolation system has the advantages of simple construction, low cost and good working reliability; When the peak acceleration reaches 0.1g, the base isolation system will start working effectively, which can significantly reduce the seismic effect applied to the upper structure; The proposed new anti-seismic system is more reasonable in anti-seismic design and has higher anti-seismic capacity, slower stiffness degradation, better ductility. And it can significantly improve the comprehensive seismic performance of rural housings. The new base isolation system and the new anti-seismic system proposed in this paper are suitable for applying in rural areas in China.
  • Cheng Xuan-sheng;Tian Rui-rui;Zheng Ying-ren
    . 2011, 30(11): 214-218,.
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    In order to verify the impact of stress concentration phenomenon at the feet of vertical ridge loess tunnel (hole) on the rock structure safety factor, in this paper, according to the static and dynamic analysis model, and using the shear strength reduction method and the ANSYS software, and being based on the existing study results, the change laws of plastic zone and safety factor are analyzed under the action of gravity and seismic when the angles are right at the feet of vertical ridge loess tunnel (hole), and through numerical examples the change laws of rock structure safety factor are studied when the angles are arc that the radius is different. The results shows that: the plastic zone under the gravity action firstly appears at upper foot of vertical ridge loess tunnel (hole), the stress concentration phenomenon of right angle has no effect on wall rock safety factor, and the plastic zone under earthquake action firstly appear at the right foot of vertical ridge unlined loess tunnel (hole), but the decrease of safety factor is’ t the reason of stress concentration phenomenon. And so a theory basis will be provided for the loess tunnel forming and engineering application.
  • Zhao Xiang;Wang She-liang;Zhou Fu-lin;Huang Xiang-yun;Zhao Xi-cheng
    . 2011, 30(11): 219-223.
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    In the light of the ancient building protecting principle “First protect” and “Repair like the old”, 3 SMA dampers are designed; a protection scheme in the ancient pagoda structure which can improve the earthquake resistance of the pagoda is proposed; shaking table tests are performed on the model structure of pagoda in the cases the SMA dampers is erected or unerected.Test ressults demonstrates that the SMA dampers could fulfill the valid seismic energy dissipation, effectively strengthen the seismic capacity of mosque pagoda structure and is worth further exploiting and extensively applying.
  • Peng Yong-bo;Li Jie
    . 2011, 30(11): 224-229,.
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    A family of multi-objective probabilistic criteria for stochastic optimal control of base-excited structures is developed in the present paper. It includes the two criteria aiming at the ensemble-expectation and exceedance probability of equivalent extreme-value processes in the sense of performance and energy trade-off respectively. Numerical investigations show that the effectiveness of response control hinges on the physical origin of the probabilistic criteria. The exceedance probability criterion in energy trade-off sense accommodates system performance to a better trade-off between response reductions and control requirements, which is included in the comparative study against other control criteria currently in use. A randomly base-excited eight-storey shear frame, moreover, controlled by active tendons is investigated as a numerical example. Numerical results reveal that using the advocated probabilistic criterion, the structural stochastic optimal control operates efficiently and achieves a desirable objective performance.
  • Teng Jun;Xing Hou-bing
    . 2011, 30(11): 230-235.
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    This paper studies the key technology for implement of AMD control system used in high-rising building. For the feasibility to execute real-time control, the structure is reduced to a reduced order model, which almost has the same dynamic performances as the original structure. And the reduced order model can meet the precision and efficiency requirements. Then based on the reduced order model, three active control algorithms including H2/LQR, pole assignment, and fuzzy control algorithm are designed and analyzed for the optimal one with its parameters. At the same time, a acceleration-based state obsever is designed, by which the locations of accelerometers are determined.
  • Du Yong-feng;;Zhu Qian-kun ;Li Hui
    . 2011, 30(11): 236-239.
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    The large deformation behavior of series isolation system that the rubber bearing connected with the basement column has been studied. The geometric nonlinear equations were obtained by the Timoshenko beams modal, based on the axial elongation and first-order shear deformation theory. Then the large deformation behaviors of series isolation system were analyzed by using differential quadrature element method. The results show that the large deformation of Series Isolation System mainly occurred in the rubber bearings, and the internal force distribution on the column, the theoretical results are consistent with the test.
  • Cao Hai-yun;Pan Peng;Ye Lie-ping
    . 2011, 30(11): 240-244.
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    框架摇摆墙结构是框架和摇摆墙组成的新型结构体系。以一个按现行规范正常设计的6层混凝土框架为例研究该结构体系的抗震性能。利用通用有限元程序Abaqus并结合清华大学开发的PQFiber用户子程序库,建立了该框架结构附加摇摆墙前后的弹塑性模型,并进行了推覆分析。分析结果表明:(1)摇摆墙可显著提高结构整体承载力及延性;(2)尽管摇摆墙对“强梁弱柱”的屈服机制无明显改善作用,摇摆墙仍可使层间变形趋于均匀,防止层倒塌模式的出现;(3)摇摆墙的受力特点与竖向放置的简支梁类似。
  • Huan Shi;Tao Wei-jun;Jiang Guo-ping;Li Xiao-yong
    . 2011, 30(11): 245-248.
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    Based on the principles of nonlinear vibration isolation, the hardening nolinear vibration isolation device was designed, which carries out the experimental study for a nonlinear vibration isolation system with a kind of steel, rubber as the isolating element to obtain the system’s chaotic characteristic parameter range. The mechanical properties of the device parameters were obtained by experiment. And obtained by numerical calculation of the dynamic behavior of the device model. The result shows that the bechvior of the device from the period bifurcation into chaotic state gradually, Line spectrum from a single spectral structure into a broadband spectral structure, and the chaotic vibration isolation’s insulation performance is preferable for line spectra isolation.
  • Liu Wei-qing;Wang Hai;Wang Shu-guang;Du Dong-sheng;Li Wei-wei
    . 2011, 30(11): 249-253,.
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    This paper puts attention on the application of Chebyshev complex polynomials in the development of extensible lumped-parameter model of pile group foundation. The present method is an important extension to the concept of polynomial-fraction approximation in the foundation modeling. In the present analysis, pile group impedance function is obtained based on Thin Layer Method. A ratio of two Chebyshev complex polynomials is adopted to represent the normalized flexibility function of pile group foundation. Through performing partial-fraction expansion on this Chebyshev complex polynomial-fraction, Chebyshev complex polynomial-fraction is designed two basic discrete-element models. The accuracy and validity of the lumped-parameter model is extensively investigated for the case of pile group foundation. The proposed method may be easily applied to analyze various practical problems in soil-structure interaction in time domain and nonlinear analysis
  • Du Xiu-li;Chen Ming-qi;Han Qiang
    . 2011, 30(11): 254-259.
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    In order to further study the seismic behavior of reinforced concrete hollow bridge columns and factors influencing,five reinforced concrete hollow bridge columns models with large ratio were built and tested to failure under the combined action of constant axial load and reversed cyclic laterl load.The aim of this paper is to evaluate seismic performance of all the five models,and variables included longitudinal reinforcement ratio,spiral reinforcement ratio,axial load ratio,influence seismic performance,such as failure mode,hysteretic behavior,load-carrying capacity,ductility. Analysis of the experimental results suggest that the seismic performance of reinforced concrete hollow bridge columns is great,influence of variables obey the theory of reinforcement concrete.With such hollow pier in engineering,we can save material dramtically,and have enough security of safety.
  • Wang Shu-guang;Lu Wei-dong;Liu Wei-qing;Sun Zhen
    . 2011, 30(11): 260-265.
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    The Kunming new international airport terminal is one of the world’s largest seismic isolation buildings at present. The layout scheme of the seismic isolation layer is described in detail. The finite element model of the terminal is established and the dynamic responses are also analyzed. The shaking table test is carried out for the Kunming new international airport terminal. The scale factor of the model structure used in the test is 1/60. And the layout of the seismic isolation layer is also simplified. The results show the vibration-reduction effects of the seismic isolation building are about 50%. Finally, the seismic performances of the prototype structure are analyzed. Dynamic characteristics, acceleration responses and displacement responses of the prototype structure are investigated under different levels of earthquake. Compared with the shaking table test’s results, it is shown that the finite element analysis results are agreed well with the experimental results. The Kunming new international airport has clear isolation mechanism and good isolation effect with the theoretical and experimental proof. It is feasible and effective for applying the base isolation technology to long-span structures.
  • Han Jian-ping;;Wang Hong-tao;Liu Yun-shuai;;Du Yong-feng;;Li Hui;
    . 2011, 30(11): 266-271.
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    Ambient vibration tests were conducted on the two base-isolated buildings. Modal frequencies,mode shapes and modal damping ratios were identified using Stochastic Subspace Identification (SSI) and Rational Fraction Polynomial (RFP) methods. The identified results show that under ambient excitation, fundamental frequency of these two base-isolated structures is much larger than the value under frequently occurred earthquake level. And the equivalent viscous damping ratio is as low as the value of non-isolated structure, so base-isolated structures can be considered as the classical proportional damping system under ambient excitation. Furthermore, taking one of the two buildings as case study, identified modal parameters were used as the updating benchmark and the actual equivalent horizontal stiffness of isolation layer was inversed using the multi-objective optimization method. The results show that the actual stiffness value is 10.9 times of that in the design case under frequently occurred earthquake level. Finally, preliminary finite element model were updated based on the inversed stiffness of the isolation layer and the updated model was analyzed numerically. Comparison of the results between analysis and test indicates that the updated model can represent the dynamic characteristics of the base-isolated structure under ambient excitation more reliably.
  • Qi Ai;Shang Hao-jiang
    . 2011, 30(11): 272-280.
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    The limit of height-width ratio of high-rise base-isolated structure with rubber bearings is investigated. With 3-particle model being adopted, The derivation of limit ratio formulas are performed and the results are presented corresponding to various kinds of building categories, earthquake fortification intensities, site classifications, and damping ratios of structure. In conformity to the principle of simplicity and safety, the calculated limit ratios are summarized. By comparing the results with which adopted single-particle model, it is shows that there is little difference between them, which is indicated that high-order modes have little effect on the limit of height-width ratio of high-rise base-isolated structure. The changes of the high-width ratio are further discussed when the basic period is not equal to the critical period, and it is found that when the basic period is less than the critical period the limit of height-width ratio dose not significantly reduce, and when the basic period is greater than critical period the limit of height-width ratio reduce obviously.
  • Tan Ping;Ying Wei-xi;Zhang Ying
    . 2011, 30(11): 281-286.
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    This paper proposes a near-field ground model. Motion equation of an inter-story isolated eccentric structure is formulated. Based on three-rigid panel model of the inter-story isolated eccentric structure, influence of eccentric parameters on the inter-story isolated structure is investigated. Near-field effect on the inter-story-isolated eccentric structure is analyzed by adjusting the pulse period and proportion of pulse component. Optimization law of viscous dampers, which are installed on the isolation story, are developed in this paper. Numerical simulation is conducted to verify the control effectiveness of nonlinear viscous dampers. Results show that the optimal viscous damper can reduce the responses of the substructure, isolation level and superstructure of the inter-story isolation system significantly and greatly enhance the safety of inter-story isolated eccentric structure subjected to near-field ground motions.