Soon Jong Yoon

Experimental Investigation on the Structural Behavior of Shear Connectors Used in the FRP and Concrete Bridge Deck System

Feasibility study on the use of newly developed FRP and concrete composite bridge deck system is conducted. To lengthen the service life of bridge deck, the steel-free bridge deck system is developed. In this deck system, shear connectors between FRP module and concrete are utilized and structural behavior of shear connectors is investigated experimentally. The result of an investigation reveals that the system is promising.

An Experimental Study on the Shear Behavior of Perforated Shear Connector with Flange Head

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.

Structural Design for the Development of the floating Type Photovoltaic Energy Generation System

In this paper, we present the structural design for the development of the floating type photovoltaic energy generation system using pultruded FRP members. Pultruded FRP has superior material properties compared with those of conventional structural materials. Especially, pultruded FRP has an excellent corrosion-resistance along with high specific strength and stiffness, which are highly appreciated for the design and fabrication of the floating type photovoltaic energy generation system. In the paper, investigations pertaining to the mechanical and structural behaviors of FRP structural members based on the experiments are discussed. In addition to the experimental investigation, finite element analysis of the floating type photovoltaic energy generation system composed of pultruded FRP structural shapes has been performed. Finally, we have designed and developed the floating type photovoltaic energy generation system using the results of investigations.

Development of FRP-Concrete Composite Bridge Deck in Korea - State-of-the-Art Review -

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.

Evaluation of Load Carrying Capacity of the Perforated Shear Connector with Flange Heads

In the construction of composite bridge structures, various types of shear connectors are usually used to provide an efficient load transfer and the composite action of two or more different materials. In the previous work conducted by authors, a new type of the shear connector was introduced, which is the perforated shear connector with flange heads (T-shaped perforated shear connector), and the structural behavior of the shear connector was discussed based on the results of push-out tests. For the practical design of new shear connector, it is necessary to develop the equation for the prediction of the load carrying capacity of the shear connector. In this study, the existing design equations for the Perfobond shear connector were briefly analyzed and the equation for the prediction of the shear capacity of T-shaped perforated shear connector was suggested empirically. By comparing the results obtained by the suggested equation, the existing equations for the Perfobond shear connector, and the experiment, the applicability and effectiveness of the suggested equation was estimated.

Elastic Buckling of Orthotropic Open Section Compression Members with Edge Stiffeners

In this study, elastic buckling behavior of an orthotropic open section compression member with edge stiffener, which is one of the reinforcing methods for increasing local buckling strength of compression members, is investigated. In order to perform the local buckling analysis on the orthotropic structural shapes, the buckling analysis of orthotropic plates having various boundary conditions has to be done prior to performing the local buckling analysis since the structural shapes are composed of number of plate elements. Using these buckling analysis of the orthotropic plates, the closed-form characteristic equation for the local buckling of the orthotropic channel and I-shape compression members stiffened by the edge stiffener in their free edges is derived. Based on the results of the investigation, the minimum buckling coefficients with respect to the ratio between plate elements and the ratio between plate element to stiffener for the channel and I-shape compression members are shown graphically. This study shows the minimum buckling coefficient of orthotropic open section compression members with edge stiffeners is significantly increased in comparison with that of the columns with no edge stiffeners. Simple verification of the equation derived is performed by substituting the orthotropic material properties for isotropic ones and it is observed that the result is very close to that in published documents.

Design Consideration of the Nonuniform Stress Distribution of Pultruded Structural Member under Compression

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.

Form Factor for the Design of Pultruded FRP Structural Members under Compression

As a new construction material, fiber reinforced polymeric plastic structural shapes are readily available. Therefore, construction and structure rehabilitation using FRP materials are an ever increasing trend because of FRP material’s superior chemical and mechanical properties compared with those of conventional construction materials such as steel and concrete. Among the FRP materials, pultruded fiber reinforced polymeric plastics are the most popular for civil engineering applications. However, it has relatively low modulus of elasticity and also cross-section of structural shapes is composed of plate components such as flange and web. Therefore, stability is an important issue in the design of pultruded structural shapes. For the design of pultruded structural member under compression, buckling and post-buckling strengths of plate components should be taken into account. In the structural steel design following AISC/ LRFD, this effect, in addition to the buckling strength, is incorporated with a form factor. In this research, the form factor for the design of pultruded structural shapes under compression is investigated. Based on the analytical study, the form factor for the design of pultruded structural shapes have been suggested.

Perforated FRP Shear Connector for the FRP-Concrete Composite Bridge Deck

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.

Buckling of Composite Thin-Walled Members

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.