Papers by Author: Soon Jong Yoon

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Authors: Seung Sik Lee, Soo Ha Chae, Soon Jong Yoon, Sun Kyu Cho
Abstract: The strengths of PFRP thin-walled columns are determined according to the modes of buckling which consist of local mode for short columns, global mode for long columns, and interaction mode between local and global modes for intermediate columns. Unlike the local and global buckling, the buckling strength of interaction mode is not theoretically predictable. Refined theoretical approaches which can account for different elastic properties of each plate component consisting of a PFRP thin-walled member are used. Based on both the analytical buckling loads and the experimentally measured buckling loads from literatures, the accuracies of Ylinen’s equation and modified AISC/LRFD column design equation for isotropic steel columns were compared. From the comparison, it was found that the modified AISC/LRFD column design equation is more suitable for the prediction of the buckling loads of PFRP thin-walled members than Ylinen’s equations.
Authors: Joon Seok Park, In Kyu Kang, Jong Hwa Park, Joo Kyung Park, Hong Taek Kim, Soon Jong Yoon
Abstract: In construction industries, new construction materials are needed to overcome some problems associated with the use of conventional construction materials due to the change of environmental and social requirements. Accordingly, the requirements to be satisfied in the design of civil engineering structures are diversified. As a new construction material in the civil engineering industries, fiber reinforced polymeric plastic (FRP) has a superior corrosion resistance, high specific strength/stiffness, etc. Therefore, such properties can be used to mitigate the problems associated with the use of conventional construction materials. Nowadays, new types of bridge piers and marine piles are being studied for new construction. They are made of concrete filled fiber reinforced polymeric plastic tubes (CFFT). In this paper, a new type of FRP-concrete composite pile which is composed of reinforced concrete filled FRP tube (RCFFT) is proposed to improve compressive strength as well as flexural strength of an RCFFT. The load carrying capacity of proposed RCFFT is discussed based on the result of experimental and analytical investigations.
Authors: Y.H. Kim, S.K. You, Jae Ho Jung, Soon Jong Yoon, Seung Sik Lee
Abstract: Concrete-steel composite members are formed by bonding a steel component, such as an I-section beam, to a concrete component, such as a reinforced concrete slab, so that the two components can act as a unit. The use of such type of composite member becomes main stream of construction technology since it provides efficient load resisting mechanism in structural system. In a composite member, bond between steel and concrete is a crucial factor for the composite action. Usually this bond behavior is achieved by installation of mechanical device so called shear connector. The composite action can be divided into two categories (i.e., full and partial) depending on the shear strength of mechanical shear connector embedded in the concrete, i.e., understanding of shear load resisting mechanism is necessary to develop a new shear connector for better, wider and more efficient application of composite action. For this purpose, the push-out tests are performed for the evaluation of several existing shear connectors including carefully designed perforated shear connector with flange head. One of the purposes of this experimental research is to define the shear resisting mechanism of the proposed new type shear connector. The experimental results show that the degree of composite action using perforated shear connector with flange head is superior to those of existing shear connectors such as a general headed stud, perfobond, etc. The experimental parameters, such as the number of perforated holes, the distance between perforated holes, and the height of shear connector, are carefully chosen for the verification of their effect on the capacity of shear resistance. From this experimental investigation it was found that the mechanical performance of proposed shear connector was efficient as a rigid shear connector.
Authors: Sun Hee Kim, Soon Jong Yoon, Won Chang Choi
Abstract: In this paper, the results of experimental and analytical investigations pertaining to the structural behavior of glass fiber reinforced polymer plastic (GFRP) pipes are presented. GFRP is assumed as an orthotropic material. Mechanical properties along the longitudinal and hoop direction of the pipes are determined by the tension and compression tests. The parallel plate loading tests for the GFRP pipes were conducted to findthe relation between load and ring deflection. Inaddition, the finite element analysis (FEA) for the GFRP pipes was conducted using the material properties obtained from test in the study. The numerical results obtained by the finite element method show good agreement with the parallel plate loading test results for GFRP pipes.
Authors: Jong Ho Yoo, Sun Hee Kim, Won Chang Choi, Soon Jong Yoon
Abstract: The pultruded fiber reinforced polymer plastic (PFRP) is one of the most actively studied materials for structural member in construction industries. In this study, a buckling analysis of PFRP plate is conducted by two analysis methods. First, a buckling strength of PFRP plate is calculated by the exact orthotropic plate buckling analysis. Second, simplified buckling analysis for PFRP plate is conducted by using approximate orthotropic material properties. The approximate orthotropic material properties are geometric mean value of longitudinal and transverse material properties of original PFRP plate. As a result of buckling analysis, buckling strength of PFRP plate for each analysis method can be obtained. From the comparison between these results, advantages and disadvantages of each analysis method are discussed. In addition, it is also discussed whether the simplified buckling analysis method for PFRP plate is applicable for the design.
Authors: Seung Sik Lee, Soon Jong Yoon, S.K. Cho, Jong Myen Park
Abstract: Pultruded fiber reinforced polymer (FRP) structural members have been used in various civil engineering applications. T-shapes are commonly used for chord members in trusses and for bracing members. In these cases, T-shapes are mainly subjected to axial forces, and stability of a member is one of the major concerns in the design. Due to the monosymmetry existing in the cross-section of T-shapes, T-shapes are likely to buckle in a flexural-torsional mode. An energy solution, using the Ritz method, to the buckling problem of a pulturuded T-shape under uniform compression is derived based on a composite thin-walled beam theory developed by Bauld and Tzeng. The solution accounts for the bending-twisting and bending-extension coupling effects. The derived energy solutions are compared to the experimental results of buckling tests conducted on seventeen pultruded T-shapes. It is found that the ratios of the experimental to analytical results are in the range of 1.00 to 1.32.
Authors: Seung Sik Lee, Soon Jong Yoon, Sung Yong Back
Abstract: The use of pultruded fiber reinforced polymeric (FRP) members in civil engineering applications can greatly reduce construction time and maintenance cost of structures, because pultruded members have high specific strength and excellent corrosion resistance compared to steel and concrete. Pultruded members for civil engineering application are mostly made of a polymeric resin system reinforced with E-glass fibers and, as a result, they have low elastic moduli. Therefore, stability is an important issue in the design of pultruded members. In this paper, the results of an experimental investigation into the global buckling behavior of pultruded thin-walled members subjected to axial compression are presented. The analytical solutions are validated through a comparison with the results of FE analysis as well as the experimental results.
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: So Young Park, Hoon Choi, Seung Cheol Baek, Hyo Jin Kim, Soon Jong Yoon
Abstract: Recently the demand for demolition of unnecessary cylindrical silo structure is increasing due to the deterioration and malfunctional conditions and the issue of demolition is in the limelight. To minimize environmental hazards caused during the process of demolition, the explosive demolition method has been applied increasingly. The concrete silo structure is often built by the slip-form method which is a continuous concrete casting operation. As a result, the structure does not have expansion joints or other structural weaknesses that can be used to assist in the demolition process. This study presents the pre-weakening of explosive demolition of the cylindrical concrete silo structure by overturning method. Pre-weakening for the explosive demolition of the structure is usually conducted based on the field experience without technical guideline for the pre-weakening procedure. Hence, there always exist safety-related concerns. To demolish the structure by blast effectively and safely, rational approach to the pre-weakening and evaluation method of the load carrying capacity of the pre-weakened structure should be established. To do this, mechanical properties of concrete are estimated by experiment prior to structural analysis. Based on the result of investigation, design or operation methods of pre-weakening for the blast demolition are discussed.
Authors: Sang Kyoon Jeong, Soon Jong Yoon, Won Sup Jang
Abstract: The structural shapes or plates with varying thickness are often adopted in aerospace industries such as a skin structure of an airplane and civil engineering fields where the load effects are varied along the longitudinal axis of the member. Specially, the structural steel tapered plate, so called LP (longitudinally profiled) plate, has been used in many countries as a part of main member of bridges, buildings, etc. This paper presents the result of an analytical study pertaining to the local buckling behavior of FRP (Fiber Reinforced Plastic) flexural member. The flexural member is consisted with uniform thickness web and flange tapered in thickness. The boundary conditions of flange plate in its unloaded edges are elastically restrained, but they are assumed to be either fixed-free or simple-free for simplicity. In the analysis, the Galerkin form of Rayleigh-Ritz method is adopted. The buckling equation of isolated unstiffened tapered plate elements having fixed-free or simple-free boundary condition in its unloaded edges is derived. The plate buckling coefficients with respect to the thickness ratios and plate aspect ratios are calculated and presented in a graphical form. Unlike the buckling of plate with uniform thickness, discontinuous changes of buckling mode are not exist. In addition, the critical slenderness ratio of such an unstiffened tapered plate element is suggested to prevent buckling.
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