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J0-013
13:30
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13:45
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DEVELOPMENT OF ASYMMETRIC BOUC-WEN MODEL WITH LINEAR STRENGTH-DEGRADATION FUNCTIONS
In this study, an asymmetric Bouc-Wen model (BW model) is developed in which strength degradation is modeled with piecewise linear functions. This paper first reviews previous models, including the original BW model, the Wang-Wen model, and the generalized BW model and its modified version. In order to accurately describe the asymmetric strength degradation often encountered in many seismic engineering applications, this study extends the BW models with combining piecewise linear functions. A framework for parameter identification is then formulated, describing the objective function and constraint conditions required for the convex piecewise post-yielding functions. The proposed model is verified on the basis of the cyclic seismic test results of welded steel moment connections with composite floor slabs.
Cheol-Ho Lee, Sung-Yong Kim
Asymmetric hysteresis, Bouc-Wen model, Hysteresis model, Welded steel moment connections
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J0-012
13:45
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14:00
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Parametric analysis of a nonlinear tuned mass damper on a bridge using incremental harmonic balance method
With the increasing requirements for bridge safety, more and more people are considering the nonlinearity of tuned mass damper (TMD). When solving nonlinear problems, numerical calculations have problems such as slow calculation speed and difficulty in calculation accuracy control. However, the incremental harmonic balance method (IHBM) can effectively solve these shortcomings. This study investigates the vibration response of a Euler-Bernoulli bridge equipped with a nonlinear TMD, which subjected to a concentrated harmonic excitation at a point on the beam. Using nonlinear dynamics theory, the kinetic energy, potential energy, and dissipative energy function of the bridge and nonlinear TMD is built up in the continuous expression. By means of the Lagrangian equation and Galerkin truncation, this energy expression gives rise to the governing equations of vibration for the bridge and nonlinear TMD. Furthermore, the governing equations are discretized by the vibration mode superposition method and then are analyzed by the incremental harmonic balanced method. The effects of the mass ratio, location, stiffness and damping of nonlinear TMD are numerically investigated. Result shows that incremental harmonic balance method can effectively solve the vibration response problem of nonlinear TMD bridge systems. In addition, the proper selection of the mass ratio and location of nonlinear TMD can make the performance of a nonlinear TMD better.
Feng Gu, Chiu Jen Ku, Zhuhong Ouyang
harmonic excitation, incremental harmonic balance method, nonlinear tuned mass damper, parameter analysis
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J1-012
14:00
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14:15
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ARTIFICIAL TRACTION BOUNDARIES FOR SOIL-STRUCTURE INTERACTION ANALYSES USING THE FINITE ELEMENT METHOD
Soil-structure interaction (SSI) analyses allow engineers and researchers to better understand seismic performance of structures, and are generally required in structural design of important, unusual and sensitive buildings, e.g. nuclear power plants and dams. Among many modeling techniques, finite element modeling of soil and structures simultaneously in time domain is a popular choice, especially when a high degree of plasticity is expected. In practice only part of soil in real field is (and can be) included in finite element analyses. Therefore, artificial boundaries are necessary to represent dynamic behavior of adjacent soil beyond boundaries of the computational domain. This study applies the classic viscous boundary to absorb outgoing waves, and adopts results of site response analyses (which have been perform independently first) to evaluate artificial tractions at the domain boundaries. With this new proposed modeling scheme, boundaries of SSI model can be in any shape and hence can be optimized for the classic viscous boundary, if desired. The enhanced boundary modeling scheme are validated using few free-field seismic wave propagation problems.
WEN-CHIA YANG, CHE-YU CHANG, CHIUN-LIN WU
absorbing boundary, finite element method, seismic wave propagation, semi-infinite domain, soil-structure interaction
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J1-014
14:15
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14:30
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BRIEF INTRODUCTION OF SHAKING TABLE TEST OF 1/25 SCALE MODEL OF OFFSHORE WIND TURBINE WITH JACKET FOUNDATION
According to the domestic energy policy, Taiwan government aims to increase wind power installed capacity up to 5.5GW by 2025. The abundant wind resources in Taiwan, particularly west coast, is one of the benefit to develop renewable energy. However, natural hazards such as typhoons or earthquakes strike all the time. It is necessary to ensure the safety of wind turbine and its supporting structure suffer strong wind or seismic force. A 1/25 scale model of offshore wind turbine with jacket foundation is tested in NCREE Tainan Laboratory. The model includes wind turbine tower, jacket and pipe foundation, which is installed in the shear box filled with water and sand to simulate seabed environment, and excited by white noise, sinusoidal excitation and near-fault artificial earthquake. The analysis of testing data is still ongoing, and the expected results include structure-soil interaction, soil liquefaction, and shock absorption technique for wind turbine with jacket foundation.
Kuang-Yen Liu, Shen-Haw Ju, Bai-Yi Huang, Sheng-Huoo Ni, Yung-Yen Ko, Shang-Yi Hsu, Yu-Wen Chang, Lyan-Ywan Lu, Ging-Long Lin
Earthquake Engineering, near-fault earthquake, Soil Liquefaction, wind turbine with jacket foundation
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J0-011
14:30
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14:45
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A Versatile Small-Scale Structural Laboratory for Developing Advanced Experimental Methods
In the past decades, various advanced experimental methods have been developed and validated in order to meet the test requirements for new structural systems and energy dissipating devices in a cost-effective manner. A versatile small-scale structural laboratory has been designed and constructed in the Taipei Laboratory of National Center for Research on Earthquake Engineering (NCREE) for verifying the effectiveness of newly developed technology before it is essentially applied to full-scale structural testing for the safety purpose. This laboratory is equipped with six dynamic servo-hydraulic actuators that are regulated by a state-of-the-art digital controller. Two orthogonal reaction walls and one T-slotted reaction floor are allocated in the laboratory to mount the fixtures and specimens through high strength threaded bolts. Accordingly, a large variety of experimental setups can be completed by installing hydraulic actuators and fixtures depending on different research objectives. In addition, three different real-time computing machines and one high-performance computing system powered with a graphical processing unit are obtainable in the laboratory, providing diverse hardware selections for developers. This small-scale structural laboratory provides a safe and versatile environment for researchers to develop and validate novel and advanced experimental technology. International collaboration between NCREE and the institutes worldwide is encouraged and expected in order to achieve considerable mutual success and benefit on advanced experimental technology for earthquake engineering.
Pei-Ching Chen
advanced experimental technology, digital controller, real-time machine, servo-hydraulic actuator, small-scale laboratory
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J1-011
14:45
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15:00
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Seismic Control Performance Evaluation of A Smart Base-Isolated Raised Floor System using Real-Time Hybrid Simulation
Sloped rolling-type isolation has been demonstrated as one of the most effective methods to mitigate seismic damages of equipment and facilities above raised floor systems for high-tech industry. However, pounding against surrounding walls may cause enormous pecuniary loss if excessive displacement response arises during strong or long-period excitations. Although supplemental damping can suppress the displacement response, it also increases the absolute acceleration transmitted to the top of the raised floor. In order to resolve this issue, a smart base-isolated raised floor system is proposed in this study. This system contains multiple sloped rolling-type isolation devices and magnetorheological (MR) dampers allocated regularly underneath the raised floor. Real-time hybrid simulation is adopted to assess the control performance of the smart base-isolated raised floor system. One of the MR dampers is physically tested in the laboratory while the rest of the system are numerically simulated. In order to consider the floor amplification effect on the control performance, the smart base-isolated raised floor system is assumed to be assembled at the roof and ground level of a building. Four control algorithms are designed for the MR dampers including passive-on, switching, modified switching, and fuzzy logic control. Six artificial spectrum-compatible input excitations and three slope angles of the isolation devices are considered in the RTHS. Experimental results reveal that a balanced control performance between the absolute acceleration and relative displacement of the smart base-isolated raised floor system can be achieved successfully.
Pei-Ching Chen, Shiau-Ching Hsu, You-Jin Zhong, Shiang-Jung Wang
magnetorheological damper, raised floor system, Real-time hybrid simulation, sloped rolling-type isolation
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