Lee Young Hak

In process monitoring that is based on statistical models, adaptive monitoring techniques have been developed to reflect frequent changes in the operating conditions. The key to adaptive monitoring of real industrial processes is to distinguish process operating condition changes from variations due to disturbances. This paper proposes a systematic method for detecting process state changes and classifying them as operating condition changes or variations as a result of disturbances. The key ide

The traditional P-wave ultrasonic measurement has been used for the condition assessment of general reinforced concrete structures for a long time, but the effects of prestressing applied to concrete structures such as long-span buildings and bridges on ultrasonic pulse velocity have not been studied clearly. Therefore, this study analyzed the statistical distribution of P-wave ultrasonic pulse velocities in reinforced and prestressed concrete slabs of 3000 × 3000 mm with a thickness of 250 mm.

The recycling of industrial waste such as bottom ash from furnaces is an important issue in construction industry, since it enables reduction in construction cost and has beneficial effect on the environment. In this study, we have investigated the bond characteristics of steel deformed bars embedded in artificial lightweight aggregate concrete which is manufactured from bottom ash. A pullout test was performed on 144 lightweight aggregate concrete specimens to measure the bond strengths. In thi

Abstract The bond behavior of reinforcing bars is an important issue in the design of reinforced concrete structures and the use of fiber reinforced polymer (FRP) rebars is a promising solution to handle the problems of steel reinforcement corrosion. This study investigates the bond characteristics of carbon and aramid FRP (CFRP and AFRP) bars embedded in normal strength concrete. A pullout test was performed on 63 normal strength concrete specimens reinforced with FRP and steel rebars with diff

Abstract Concrete‐filled carbon fibre‐reinforced polymer (CFRP) composite columns without longitudinal and transverse reinforcing steels were tested to perform both experimental and analytical investigations of the axial behaviour of circular columns confined with CFRP composite tubes. The tubes were manufactured by wrapping the CFRP sheets with 90° + 90°, 90° ± 75°, 90° ± 60°, 90° ± 45°, 90° ± 30° wrapping angles with respect to longitudinal axis of the tube. Monotonic axial loads were applied

This paper presents the shear capacities of concrete beams reinforced with glass fiber reinforced polymer (GFRP) plates as shear reinforcement. To examine the shear performance, we manufactured and tested a total of eight specimens. Test variables included the GFRP strip-width-to-spacing ratio and type of opening array. The specimen with a GFRP plate with a<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mn>3</mml:mn><mml:mo>×</mml:mo><mml:mn>2</mml:mn></mml:math>opening arr

In recent years, the Lamb wave analysis by the multi-channel analysis of surface waves (MASW) for concrete structures has been an effective nondestructive evaluation, such as the condition assessment and dimension identification by the elastic wave velocities and their reflections from boundaries. This study proposes an effective Lamb wave analysis by the practical application of MASW to concrete wide beams in an easy and simple manner in order to identify the dimension and elastic wave velocity

In the existing reinforced concrete columns where they are insufficient seismic details, critical failure mode such as shear failure can be observed under seismic loads. One strategy for the retrofitting of existing concrete columns is to use concrete jacketing. Concrete jacketing consists of a new concrete layer with longitudinal and transverse reinforcements, and can improve seismic resistance capacity. In this paper, a detail of concrete jacket that can be expected for easy construction and i

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Many structural retrofitting methods tend to only focus on how to improve the strength and ductility of structural members. It is necessary for developing retrofitting strategy to consider not only upgrading the capacity but also achieving rapid and economical construction. In this paper, a new retrofitting details and technique is proposed to improve structural capacity and constructability for retrofitting reinforced concrete beams. The components of retrofitting are prefabricated, and the com

In this study, the structural behavior of reinforced concrete flat plates shear reinforced with vertical grids made of a glass fiber reinforced polymer (GFRP) was experimentally evaluated. To examine the shear strength, experiments were performed on nine concrete slabs with different amounts and spacings of shear reinforcement. The test results indicated that the shear strength increased as the amount of shear reinforcement increased and as the spacing of the shear reinforcement decreased. The G

An improved shear strength equation is proposed that considers transverse reinforcement spacing and support conditions for concrete wide beams. Eighteen specimens were fabricated to examine the influence of transverse reinforcement spacing, the number of transverse shear reinforcement, and support width on shear capacity. From the test results, a shear strength equation is proposed and used to evaluate the shear strength of 23 specimens from previous studies and 18 from this study. For the 41 sp