Papers by Author: Dong Min Ok

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Authors: Jin Woo Choi, Seong Sik Lee, Hyung Joong Joo, Chang Won Kim, Dong Min Ok, Soon Jong Yoon
Abstract: As a new construction material, fiber reinforced polymeric plastic structural shapes are readily available. Therefore, new construction and existing structure rehabilitation using FRP materials are ever increasing trend because of FRP material’s chemical and mechanical properties compared with those of conventional construction materials such as steel and concrete. Among the structural composites, pultruded fiber reinforced polymeric plastic structural members are the most popular for the civil engineering applications because of the cost effectiveness. However, they are made of fiber reinforced polymer resin system, they have relatively low modulus of elasticity and also cross-sections of structural shapes are composed of thin plate components such as flange and web. Therefore, structural stability is an important issue in the design of pultruded structural members. For the design of pultruded structural member under compression, buckling and post-buckling strengths of plate components may be taken into account. In the structural steel design following AISC/LRFD, in addition to the buckling strength, the nonuniform stress distribution in the section is incorporated with a form factor. In this paper, the form factor for the design of pultruded structural member under compression is investigated by experiment. Based on the experimental results, the form factor for the design of pultruded structural shapes have been suggested.
Authors: Jeong Hun Nam, Soon Jong Yoon, Hwan Doo Moon, Dong Min Ok, Soon Jung Hong
Abstract: The bridge deck is the most vulnerable element in the bridge system because it is exposed to direct actions of wheel loading, chemical attacks, and temperature and moisture effects including freezing and thawing, shrinkage, humidity, etc. In 1980’s, several countries, such as USA, Japan, and Canada, already realized that the service life of the deck is critical for that of the whole bridge, and the research was initiated to develop new material and structural system to improve deck behavior. In recent years, it has been encouraged to develop more durable, easily constructible, and more cost effective bridge deck than the current one in Korea. In this study, a concise state-ofthe- art survey of the experimental investigations on the FRP-concrete composite bridge deck under developing in Korea is presented.
Authors: Sang Kyoon Jeong, Seung Sik Lee, C.H. Kim, Dong Min Ok, Soon Jong Yoon
Abstract: Nowadays, the investigations relating to the FRP re-bars have been increased due to their superior physical and mechanical properties such as environmental resistance, electro-magnetic transparency, and high specific strength and stiffness. In this paper, we present the results of an experimental investigation pertaining to the flexural behavior of concrete beams reinforced with GFRP re-bar bundles for tension and CFRP grids for shear. A total of eight specimens, two pairs of four different shear reinforcement spaces, is loaded to failure under the 4-point bending test set-up. In addition to the experimental investigation, theoretical evaluation is also conducted according to the ACI Committee 440 for all beam specimens. Both experimental and theoretical results such as failure modes and load-deflection relations are compared and good agreements are observed.
Authors: Jeong Hun Nam, Soon Jong Yoon, Dong Min Ok, Sun Kyu Cho
Abstract: In recent years, the FRP-concrete composite bridge deck system has been introduced because of its light-weight and durability. The FRP-concrete composite bridge deck is composed of FRP module and concrete, and they are connected with shear connectors. In order to insure the composite action between FRP module and concrete, appropriate types of shear connector need to be installed. In this study, new type of FRP shear connector was suggested and the experimental investigations are conducted based on the studies of Perfobond. In the experimental study, the push-out test was conducted and the load carrying mechanism was analyzed including the friction effect of sand coating. Considering the load carrying mechanism of perforated shear connector under shear force, the empirical equation for the prediction of shear strength of perforated FRP shear connector was suggested.
Authors: Jeong Hun Nam, Seung Sik Lee, Soon Jong Yoon, Dong Min Ok, Ju Bum Kim
Abstract: This paper presents the results of experimental and analytical investigations on the behavior of GFRP pipes used in the water supply pipeline systems. The pipes consist of two filament wound outer GFRP tubes and polymer mortar between the tubes. Parallel plate loading tests were conducted and the test results were compared with predicted results. The load-deflection prediction was conducted by the FE analysis and the conventional strength of materials approach. It was shown that the results obtained by the experiment and analysis were agreed well.
Authors: Jae Wook Kim, Kwang Yeoul Shin, Dong Min Ok, Dong Jun An, Soon Jong Yoon
Abstract: Due to the advantages of FRP composite such as corrosion resistance, light weight, high specific strength and stiffness, flexibility, etc., the use of FRP composite in construction sites is increasing steadily. Especially, high corrosion resistance is a very strong point of FRP composite. Although the FRP composite has many advantages, the material properties of FRP composite under various environmental conditions at the construction sites are not well investigated. In this paper, we present the results of experimental investigations of FRP composite experiencing freezing and thawing cyclic temperature. In this investigation, we performed experimental studies to find the stress versus strain characteristics of FRP composite experiencing freezing and thawing cyclic temperature variation. In the experimental program, strength and stiffness of the pultruded FRP composite specimens under uniaxial tension affected by the freezing and thawing temperature change mechanism are evaluated and the results are discussed.
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