| Project/Area Number |
09044129
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Field |
構造工学・地震工学
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| Research Institution | Ibaraki University |
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Principal Investigator |
WU Zhishen Ibaraki Univ., Associate Professor, 工学部, 助教授 (00223438)
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| Co-Investigator(Kenkyū-buntansha) |
岑 章志 中国清華大学, 工学部, 教授
IWAMATSU Sachio Fukushima National College of Technology, President, 校長 (10160136)
HARADA Takao Ibaraki Univ., Research Associate, 工学部, 助手 (00241745)
NUMAO Tatsuya Ibaraki Univ., Associate Professor, 工学部, 助教授 (90164649)
FUKUZAWA Kimio Ibaraki Univ., Professor, 工学部, 教授 (50165271)
CEN Zhangzhi Tsinghua Univ., Professor
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥7,700,000 (Direct Cost: ¥7,700,000)
Fiscal Year 1998: ¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 1997: ¥4,600,000 (Direct Cost: ¥4,600,000)
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| Keywords | Existing large-scale brittle structures / infrared thermography system / laser doppler velocitometer / FRP sheets / damage assessment / Structural health monitoring / Intelligent adoptive Structures / Repair / strenghtening / retrofitting |
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| Research Abstract |
1. The Failure Process evaluation of Brittle Structure system : On this research topic, a failure path approach for time -variant system reliability estimation of brittle structures has been developed The March chain assumption is used to model the cumulative damage under time variant loads. The effect of load overlapping under multiple load processes is investigated. Moreover, a probabilistic model for the randomness of the progressive crack growth in a quasi-brittle material is proposed. The method is implemented by finite element approach with a smeared crack model and R-curve approach.
2. Experimental/numerical investigations on bond behavior and its improvement strategies : Through a series of experimental programs on three bending beams, double -shear specimens pulled in tension and simple shear specimens, the bond behavior of concrete-FRP interface influenced by compressive strengths, epoxy characteristics and constructional conditions, the Quantities of FRP sheets, and the rough
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ness of interface etc.has been investigated and several improvement strategies on the bond behavior and self repair of de-bonding have been also proposed. The Cohesive interfacial Crack model based on nonlinear fracture mechanics was also proposed. As the numerical analysis approach, both FEM and BEM methods were used to simulate the dc-bonding propagation.
3. Optimization of reinforcement design of FRP sheets : The hybrid concept with different kinds of FRP sheets has been developed to improve the structural behavior and optimum design method of strengthened structures was also proposed through this research. Moreover, a new method to use carbon fiber sheets which was presiressed before they were bonded to the concrete surface is developed to improve different reinforcement effects.
4. Defect and de-bonding detection and health structural monitoring system : Two detection systems with both Laser Doppler Velocitometer and Infrared Thermography have been proposed for the de-bonding or other interfacial cracks effectively. And a resistance heating cells embedded in concrete-FRP interface layer is designed in order to make a possible real -time monitoring of interfacial de-bonding. Moreover an active damage detection on crack initiation and its propagation in brittle materials and structures using a build-in network of piezoelectric transducers was proposed.
5. Decentralized Adaptive Vibration Control of Complex Structure : In this paper, a new neural network based decentralized control algorithm has been developed for active control of large scale or complex structures which were considered to be controlled with multiple actuators. The concept of information substructures decomposed depending upon the control areas of actuators was introduced successfully in the decentralized control algorithm. Results from computer-simulation studies through the comparison of different control strategies have shown the effectiveness of the proposed method.
6. Identification algorithms for the assessment of structural damages : In order to proposed an identification model for a large-scale structure system, firstly, a general framework of inverse analysis is developed for the static parameter estimation problem using Hopfield Neural Network. Secondly, a dynamic localized structural identification method with perturbation technique has been developed for large-scale structures. Moreover, a two-stage identification algorithm for the assessment of structural damages have been also developed using the modal test data. The effectiveness of all of these models were illustrated by numerically simulating several complex structural systems. Less
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