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Behavior of damaged and undamaged concrete strengthened by carbon fiber composite sheets
Ilki, Alper,Kumbasar, Nahit Techno-Press 2002 Structural Engineering and Mechanics, An Int'l Jou Vol.13 No.1
Many existing concrete structures suffer from low quality of concrete and inadequate confinement reinforcement. These deficiencies cause low strength and ductility. Wrapping concrete by carbon fiber reinforced polymer (CFRP) composite sheets enhances compressive strength and deformability. In this study, the effects of the thickness of the CFRP composite wraps on the behavior of concrete are investigated experimentally. Both monotonic and repeated compressive loads are considered during the tests, which are carried out on strengthened undamaged specimens, as well as the specimens, which were tested and damaged priorly and strengthened after repairing. The experimental data shows that, external confinement of concrete by CFRP composite sheets improves both compressive strength and deformability of concrete significantly as a function of the thickness of the CFRP composite wraps around concrete. Empirical equations are also proposed for compressive strength and ultimate axial deformation of FRP composite wrapped concrete. Test results available in the literature, as well as the experimental results presented in this paper, are compared with the analytical results predicted by the proposed equations.
Low strength concrete members externally confined with FRP sheets
Ilki, Alper,Kumbasar, Nahit,Koc, Volkan Techno-Press 2004 Structural Engineering and Mechanics, An Int'l Jou Vol.18 No.2
In this paper axial loading tests on low strength concrete members, which were confined with various thickness of carbon fiber reinforced polymer (CFRP) composite sheets are described. Totally 46 specimens with circular, square and rectangular cross-sections with unconfined concrete compressive strengths between 6 and 10 MPa were included in the test program. During the tests, a photogrammetrical deformation measurement technique was also used, as well as conventional measurement techniques. The contribution of external confinement with CFRP composite sheets to the compressive behavior of the specimens with low strength concrete is evaluated quantitatively, in terms of strength, longitudinal and lateral deformability and energy dissipation. The effects of width/depth ratios and the corner radius of the specimens with rectangular cross-section on the axial behavior were also examined. It was seen that the effectiveness of the external confinement with CFRP composite sheets is much more pronounced, when the unconfined concrete compressive strength is relatively lower. It was also found that the available analytical expressions proposed for normal or high strength concrete confined by CFRP sheets could not predict the strength and deformability of CFRP confined low strength concrete accurately. New expressions are proposed for the compressive strength and the ultimate axial strain of CFRP confined low strength concrete.
Vehicle Tests of a Longitudinal Control Law for Application to Stop-and-Go Cruise Control
Ilki Moon,Kyongsu Yi 대한기계학회 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.9
This paper presents the implementation and vehicle tests of a vehicle longitudinal control scheme for Stop and Go cruise control. The control scheme consists of a vehicle-to-vehicle distance control algorithm and throttle/brake control algorithm for acceleration tracking. The desired acceleration of a vehicle for vehicle-to-vehicle distance control has been designed using Linear Quadratic optimal control theory. Performance of the control algorithm has been investigated via vehicle tests. A millimeter wave radar sensor has been used for distance measurement. A stepper motor and an electronic vacuum booster have been used for throttle/ brake actuators, respectively. It has been shown that the proposed control algorithm can provide satisfactory performance.<br/>
A trilinear stress-strain model for confined concrete
Ilki, Alper,Kumbasar, Nahit,Ozdemir, Pinar,Fukuta, Toshibumi Techno-Press 2004 Structural Engineering and Mechanics, An Int'l Jou Vol.18 No.5
For reaching large inelastic deformations without a substantial loss in strength, the potential plastic hinge regions of the reinforced concrete structural members should be confined by adequate transverse reinforcement. Therefore, simple and realistic representation of confined concrete behaviour is needed for inelastic analysis of reinforced concrete structures. In this study, a trilinear stress-strain model is proposed for the axial behaviour of confined concrete. The model is based on experimental work that was carried out on nearly full size specimens. During the interpretation of experimental data, the buckling and strain hardening of the longitudinal reinforcement are also taken into account. The proposed model is used for predicting the stress-strain relationships of confined concrete specimens tested by other researchers. Although the proposed model is simpler than most of the available models, the comparisons between the predicted results and experimental data indicate that it can represent the stress-strain relationship of confined concrete quite realistically.
Vehicle Tests of a Longitudinal Control Law for Application to Stop-and-Go Cruise Control
Moon, Ilki,Yi, Kyongsu The Korean Society of Mechanical Engineers 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.9
This paper presents the implementation and vehicle tests of a vehicle longitudinal control scheme for Stop and Go cruise control. The control scheme consists of a vehicle-to-vehicle distance control algorithm and throttle/brake control algorithm for acceleration tracking. The desired acceleration of a vehicle for vehicle-to-vehicle distance control has been designed using Linear Quadratic optimal control theory. Performance of the control algorithm has been investigated via vehicle tests. A millimeter wave radar sensor has been used for distance measurement. A stepper motor and an electronic vacuum booster have been used for throttle/brake actuators, respectively. It has been shown that the proposed control algorithm can provide satisfactory performance.
문일기(Ilki Moon),이경수(Kyongsu Yi),이재관(Jaekwan Lee),김병수(Byoungsoo Kim) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In practical driving situation, Adaptive Cruise Control (ACC) system has to need a function that is determination of primary target among several forward vehicles. We present a multi-target tracking (MTT) ACC system which consists of three Part; track estimator using IMM-PDAF, a Primary target vehicle determination algorithm and a single-target adaptive cruise control algorithm. Three motion models: uniform motion, lane-change motion and deceleration motion, which are validated using simulated and experimental data, are adopted to distinguished large lateral motions from longitudinally· excited motions. The improvement in the state estimation performance when using three models is verified in target tracking simulations. The performance and safety benefits of a multi-model-based MTT-ACC system is investigated via simulations using real driving radar sensor data.