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Qiao G.,Key Laboratory of Structures Dynamic Behavior and Control | Yi H.,Center for Composite Material and Structure
Proceedings - 5th International Conference on Instrumentation and Measurement, Computer, Communication, and Control, IMCCC 2015 | Year: 2015

To quickly and conveniently determine the corrosion status of reinforced concrete (RC) structures, the analysis and recognition algorithms are established based on complex function approximation (CFA) and fractional derivative theory (FDT), respectively. The response characteristics of universal transfer function corresponding to the step stimulus in which the dispersion and diffusion effects are simultaneously considered are analyzed in time domain. Furthermore, the feasibility of corrosion recognition algorithm based on FDT is verified numerically according to the results of CFA algorithm. © 2015 IEEE.

Shi P.,China State Construction Engineering Corporation | Wu B.,Key Laboratory of Structures Dynamic Behavior and Control | Wu B.,Harbin Institute of Technology | Spencer B.F.,University of Illinois at Urbana - Champaign | And 2 more authors.
Structural Control and Health Monitoring | Year: 2016

The equivalent force control (EFC) method has been developed for real-time hybrid testing to replace the numerical iteration of implicit integration with a force-feedback control loop. With this control loop, the EFC method can also compensate for the time delay in real-time hybrid testing. However, the delay compensation effect of the EFC can be influenced by factors such as noises in the measured displacement. This paper discusses the influence of the measurement noises on real-time hybrid testing with the EFC. The Kalman filter is proposed to filter the noises in the measured actuator displacement for improved performance. A higher proportional gain in the PID controller, which improves the effect of time delay compensation of the EFC method, can be allowed without losing stability when incorporating the Kalman filter. A series of real-time hybrid tests were conducted, and the results validated that the EFC method with Kalman filter can effectively compensate for the time delay. Copyright © 2015 John Wiley & Sons, Ltd.

Gao S.,Key Laboratory of Structures Dynamic Behavior and Control | Gao S.,China Mobile | Guo L.,Key Laboratory of Structures Dynamic Behavior and Control | Guo L.,Harbin Institute of Technology
International Journal of Steel Structures | Year: 2015

Until now, the prototypes for finite element modeling are usually practice buildings or designed by researchers themselves which means there is no uniform standard for evaluation and comparison of progressive collapse analysis results. In this paper, using software Abaqus, a 3-D model of 20-storey building considering composite action of floor slab is developed to simulate and evaluate the behavior of high-rise composite building under sudden column failure. The methodology for the modeling techniques which could improve the computational efficiency is validated by the results from a progressive collapse test. The 20-storey benchmark building considering composite action of floor slab designed to meet American seismic code has adequate load paths and redundancy to resist the spread of local collapse due to sudden column removal. The column failure in where the column size changes does not influence the behavior of structures too much. The results of progressive collapse analysis adopting 20-storey benchmark model provide important information for standardization design to prevent progressive collapse. © 2015, Korean Society of Steel Construction and Springer-Verlag Berlin Heidelberg.

Lu X.,Key Laboratory of Structures Dynamic Behavior and Control | Zheng L.,Harbin Institute of Technology | Li H.,Key Laboratory of Structures Dynamic Behavior and Control | Cao W.,Harbin Institute of Technology | Cao W.,Pennsylvania State University
Journal of Applied Physics | Year: 2015

Phase coexistence in ferroelectric solid solutions near the tricritical point has been theoretically analyzed by using the Landau-Devonshire theory. Results revealed that different phases having similar potential wells could coexist in a narrow composition range near the tricritical point in the classical Pb(Zr1- xTix)O3 system. The potential barrier between potential wells increases with the decrease of temperature. Coexisting phases or different domains of the same phase can produce adaptive strains to maintain atomic coherency at the interfaces or domain walls. Such compatibility strains have influence on the energy potential as well as the stability of relative phases, leading to the appearance of energetically unfavorable monoclinic phases. Those competing and coexisting phases also construct an easy phase transition path with small energy barrier in between, so that very small stimuli can produce large response in compositions near the morphotropic phase boundary, especially near the tricritical point. © 2015 AIP Publishing LLC.

Xu X.,Key Laboratory of Structures Dynamic Behavior and Control | Xu X.,Harbin Institute of Technology | Li H.,Key Laboratory of Structures Dynamic Behavior and Control | Li H.,Harbin Institute of Technology | And 8 more authors.
ACS Nano | Year: 2015

Three-dimensional (3D) graphene aerogels (GA) show promise for applications in supercapacitors, electrode materials, gas sensors, and oil absorption due to their high porosity, mechanical strength, and electrical conductivity. However, the control, actuation, and response properties of graphene aerogels have not been well studied. In this paper, we synthesized 3D graphene aerogels decorated with Fe3O4 nanoparticles (Fe3O4/GA) by self-assembly of graphene with simultaneous decoration by Fe3O4 nanoparticles using a modified hydrothermal reduction process. The aerogels exhibit up to 52% reversible magnetic field-induced strain and strain-dependent electrical resistance that can be used to monitor the degree of compression/stretching of the material. The density of Fe3O4/GA is only about 5.8 mg cm-3, making it an ultralight magnetic elastomer with potential applications in self-sensing soft actuators, microsensors, microswitches, and environmental remediation. © 2015 American Chemical Society.

Shan B.,Key Laboratory of Structures Dynamic Behavior and Control | Shan B.,Harbin Institute of Technology | Zheng S.,Harbin Institute of Technology | Ou J.,Harbin Institute of Technology
Measurement: Journal of the International Measurement Confederation | Year: 2015

To monitor 3D deformations of structural vibration response, a stereovision-based 3D deformation measurement method is presented in this paper. The center extraction and feature matching algorithm of circular target is studied to obtain 3D displacement of structural vibration response. Compared with traditional edge detection algorithms, this method utilizes a Canny-Zernike combination algorithm to attain sub-pixel edge of circular target, and the location accuracy of circular target can achieve 0.02 pixel. A free vibration test of a stayed-cable model is conducted in lab. The out-of-plane and in-plane displacement time histories of three circular targets on the model are gained simultaneously. Experiment results indicate the proposed method has the good agreement with the laser LVDT in in-plane data, the first three order frequencies of stayed-cable model identified by two methods are almost consistent. It is verified that this proposed approach is reliable and useful for monitoring 3D deformations of structural vibration response. © 2015 Elsevier Ltd. All rights reserved.

Wang Z.,Key Laboratory of Structures Dynamic Behavior and Control | Wang Z.,Harbin Institute of Technology | Wu B.,Key Laboratory of Structures Dynamic Behavior and Control | Wu B.,Harbin Institute of Technology
Journal of Earthquake Engineering and Engineering Vibration | Year: 2016

Pseudo-dynamic testing is one of important seismic testing methods. During this kind of tests, slippage and elastic deformation often occur to connectors and supports because of the large force loaded, leading to discrepancy between actual specimen displacements and desired displacements. This discrepancy can reduce accuracy and reliability of test results. Outer displacement loop control is a control loop with specimen displacements treated as control variable, attached to the actuator control loop. It is an effective solution to this problem. This paper elaborates on the principle of the outer displacement loop control using PI ( proportion-integral) control, analyses difficulties of its realization on non-real time platform due to the uncertainty of the system delay, and describes in detail its realization framework on the platform software for hybrid testing, namely HyTest. With this platform and the outer loop control method, a test of step command, PDT on a single-degree-freedom structure and simulation of PDT on a 6-degrees-of-freedom structure were performed. Test and numerical simulation results show that this method is stable and reliable, and can greatly improve control accuracy of displacement loading.

Zheng L.,Harbin Institute of Technology | Lu X.,Key Laboratory of Structures Dynamic Behavior and Control | Shang H.,Harbin Institute of Technology | Xi Z.,Xi'an Technological University | And 5 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2015

Domain pattern variations with temperature were studied by polarizing light microscopy for the morphotropic phase boundary composition 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN-0.33PT) single crystal. At room temperature, the monoclinic MA phase is the dominant phase in the unpoled crystal, which coexists with a small fraction of the tetragonal (T) phase. The orientation of spontaneous polarization was calculated to be ∼4.8? away from the pseudocubic (111)C in the {001}C plane family. Under an electric field of 6 kV/cm along [011]C, a single domain orthorhombic (O) phase was induced but partially switched back to MA a few hours after the removal of the E field. It was found that the temperature induced phase transition sequence of the [011]C poled PMN-0.33PT single crystal is strongly hysteretic. On heating, the phase transition sequence is as follows: coexistence of O phase and MA→rhombohedral→monoclinicMC→cubic(C). On cooling, the phase transition sequence is given by C→T→MA. The complete set of dielectric, piezoelectric, and elastic constants for the [011]C poled PMN-0.33PT single crystal was measured, which showed the strong feature of the single domain O phase with high shear (d15=2321pC/N,d24=1941pC/N) and low longitudinal piezoelectric coefficients (d33=165pC/N). © 2015 American Physical Society.

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