• Structural Monitoring and Maintenance
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• 제6권1호
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• pp.19-32
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• 2019

One way to provide safe buildings and to protect tenants from the terrorist attacks that have been increasing in the world is to study the behavior of buildings members after being exposed to dynamic loads. Buildings behaviour after being exposed to attacks inspired researchers all around the world to investigate the effect of impact loads on buildings members like slabs and to deeply study the properties of High Performance Concrete. HPC is well-known in its high performance and resistance to dynamic loads when it is compared with normal weight concrete. Therefore, the aim of this paper is finding out the impact of dynamic loads on RPC slabs' flexural capacity, serviceability loads, and failure type. For that purpose and to get answers for these questions, three concrete slabs with 0.5, 1, and 2% steel fiber contents were experimentally tested. The tests results showed that the content of steel fiber plays the key role in specifying the static capacity of concrete slabs after being dynamically loaded, and increasing the content of steel fiber led to improving the static loading capacity, decreased the cracks numbers and widths at the same time, and provided a safer environment for the buildings residents.

• Steel and Composite Structures
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• 제22권2호
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• pp.387-398
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• 2016

In order to evaluate the effects of U shape ultra high performance concrete (UHPC) permanent form on the behaviors of Reinforced Concrete (RC) beam, a full scale RC composite beam is designed and tested with U shape UHPC permanent form and a reference RC beam with same parameters is tested simultaneously for comparison. The effects of the permanent form on the failure mode, cracking strength, ultimate capacity and deformation are studied. Test results shows that the contributions of the U shape UHPC permanent form to the flexural cracking behaviors of RC beam are significant. This study may provide a reference for the design of sustainable RC beam with high durable UHPC permanent form.

• 대한기계학회논문집
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• 제18권8호
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• pp.2123-2138
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• 1994

A study on the dynamic mechanical properties of the high strength carbon fiber epoxy composite beam was carried out. The macromechanical model was used for the theoretical analysis of the symmetric laminated composite beam. The anisotropic plate theory and Bernoulli-Euler beam theory were used to predict the effective flexural elastic modulus and the specific damping capacity of laminated composite beam. The free flexural vibration and torsional vibration tests were carried out to determine the specific damping capacities of the unidirectional laminated composite beam. The vibration tests were performed in a vacuum chamber with laser vibrometer system and electromagnetic hammer to obtain accurate experimental data. From the computational and experimental results, it was found that the theoretical values with the macromechanical analysis and the experimental data of symmetric laminated composite beam were in good agreement.

• Computers and Concrete
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• 제33권2호
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• pp.217-240
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• 2024

The purpose of this study is to propose new hysteretic characteristics of medium- to low-rise RC structures controlled by both shear and flexure. Through previous study, the dual lateral force-resisting system composed of shear and flexural failure members has a new failure mechanism that cooperates to enhance the flexural capacity of the flexural failure member even after the failure of the shear member, and the existing theoretical equation significantly underestimates the ultimate strength. In this study, the residual lateral strength mechanism of the dual lateral force-resisting system was analyzed, and, as a result, an equation for estimating the residual flexural strength of each shear-failure member was proposed. The residual flexural strength of each shear-failure member was verified in comparison with the structural testing results obtained in previous study, and the proposed residual flexural strength equation for shear-failure members was tested for reliability using FEA, and its applicable range was also determined. In addition, restoring-force characteristics for evaluating the seismic performance of the dual lateral force-resisting system (nonlinear dynamic analysis), reflecting the proposed residual flexural strength equation, were proposed. Finally, the validity of the restoring-force characteristics of RC buildings equipped with the dual lateral force-resisting system proposed in the present study was verified by performing pseudo-dynamic testing and nonlinear dynamic analysis based on the proposed restoring-force characteristics. Based on this comparative analysis, the applicability of the proposed restoring-force characteristics was verified.

• International Journal of Precision Engineering and Manufacturing
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• 제4권1호
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• pp.37-42
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• 2003

Active control of flexural vibrations of smart laminated composite beams has been carried out using piezoceramic sensor/actuator and viscoelastic material. The beams with passive constrained layer damping have been analyzed by formulating the equations of motion through the use of extended Hamilton's principle. The dynamic characteristics such as damping ratio and modal damping of the beam are calculated for various fiber orientations by means of iterative complex eigensolution method. This paper addresses a design strategy of laminated composite under flexural vibrations to design structure with maximum possible damping capacity.

• 한국구조물진단유지관리공학회 논문집
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• 제8권2호
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• pp.231-238
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• 2004

R/C교량에서 진행성 균열과 과도한 처짐에 의한 휨 내력의 저하는 차량하중에 의한 동적 반복하중으로부터 발생한다. 이러한 사실은 정적인 단조증가 하중 재하실험으로부터 획득한 자료의 동적 반복하중에서의 확인과 평가의 필요성을 제기한다. 따라서, 본 연구는 CFS로 보강된 R/C보를 단조증가하중 재하실험과 반복하중 재하실험을 동시에 수행하였다. 동적 반복하중 재하실험에 의하여, 단조증가하중 재하실험에 의한 결과의 타당성 및 적합성을 확인하고 반복하중에 의한 모멘트-곡률, 휨 강도의 감소, 균열 및 파괴 특성 등을 평가하였다.

• 소음진동
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• 제11권3호
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• pp.416-421
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• 2001

The flexural vibration of laminated composite beams with an electro-rheological(ER) fluid has been investigated to design a structure with maximum possible damping capacity. The equations of motion are derived for flexural vibrations of symmetrical, mu1ti-layer laminated beams. The damping radio and modal damping of the first bending mode are calculated by means of iterative complex eigensolution method. Finite element method is used for the analysis of dynamic characteristics of the laminated composite beams with an ER fluid. For the validation of modeling methodology using viscoelastic theory the predicted dynamic properties are compared to the measured ones by author's previous work. They are in good agreement. This paper addresses a design strategy of laminated composite under flexural vibrations with an ER fluid.

• Steel and Composite Structures
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• 제47권5호
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• pp.615-631
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• 2023

Steel corrosion induces structural deterioration of concrete-filled steel tubes (CFSTs), and any potential extreme action on a corroded CFST would pose a severe threat. This paper presents a comprehensive investigation on the lateral impact behaviour of CFSTs suffering from localised pitting corrosion damage. A refined finite element analysis model is developed for the simulation of locally corroded CFSTs subjected to lateral impact loads, which takes into account the strain rate effects on concrete and steel materials as well as the random nature of corrosion pits, i.e., the distribution patterns and the geometric characteristics. Full-range nonlinear analysis on the lateral impact behaviour in terms of loading and deforming time-history relations, nonlinear material stresses, composite actions, and energy dissipations are presented for CFSTs with no corrosion, uniform corrosion and pitting corrosion, respectively. Localised pitting corrosion is found to pose a more severe deterioration on the lateral impact behaviour of CFSTs due to the plastic deformation concentration, the weakened confinement and the reduction in energy absorption capacity of the steel tube. An extended parametric study is then carried out to identify the influence of the key parameters on the lateral impact behaviour of CFSTs with localised pitting corrosion. Finally, simplified design methods considering the features of pitting corrosion are proposed to predict the dynamic flexural capacity of locally pitted CFSTs subjected to lateral impact loads, and reasonable accuracy is obtained.

• 한국정밀공학회지
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• 제18권10호
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• pp.148-153
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• 2001

Active control of flexural vibrations of smart laminated composite beams has been carried out using piezoceramic sensor/actuator and viscoelastic material. The beams with passive constrained layer damping hale been analyzed by formulating the equations of motion through the use of extended Hamilton's principle. The dynamic characteristics such as damping ratio and modal damping of the beam are calculated for various fiber orientations by means of iterative complex eigensolution method. This paper addresses a design strategy of laminated composite under flexural vibrations to design structure with maximum possible damping capacity.

• 한국지진공학회논문집
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• 제11권1호
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• pp.29-35
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• 2007

본 연구에서는 반복 횡하중을 받는 콘크리트충전 탄소섬유튜브기둥의 휨성능 평가실험을 수행하였다. 시험체의 단면형상은 각형과 원형이며 탄소삼유튜브의 두께 및 와인딩각도(winding angle)를 실험변수로 채택하였다. 모든 시험체는 건물의 한 층 높이와 유사한 높이를 갖는 full scale 크기로 제작되었으며 3대의 가력기(actuator)를 동시에 가동시켜 축하중과 횡하중을 가력하였다. 실험결과를 분석하여 기둥의 휨강도, 변형능력 및 에너지소산능력을 평가하였으며, 횡하중에 대한 기둥의 연성거동 또한 평가되었다.