이 연구는 지진하중 작용시 RC 교각의 겹침이음부에서 발생할 수 있는 종방향 철근의 부착파괴를 방지하기 위한 FRP 래핑 보강공법에 관한 실험적 연구이다. FRP 래핑공법은 수작업 또는 장비를 이용해 교각에 유리섬유를 래핑하고 에폭시 수지를 이용해 고정시키는 공법이다. FRP 래핑공법의 내진성능 보강효과를 확인하기 위해, 겹침이음부가 존재하는 6개의 교각 실험체에 대해 준정적실험을 수행하였다. 실험결과 FRP 래핑공법으로 보강한 교각은 변위연성도 및 에너지소산 능력이 증가하 였으며, 무보강 실험체에 비해 연성거동함을 확인하였다. 또한, FRP 래핑 보강량과 보강효과는 선형비례하지 않으므로 최적 설 계를 통해 교각을 보강하는 것이 효과적임을 확인하였다.
A pultruded fiber reinforced polymer plastic (PFRP) structural is one of the most widely used composite member in construction. In generally, PFRP members is composed of plate elements so that it needs to evaluate stability problems when they are used by construction members. On the other hand, creep effect may be occurred in PFRP members under sustained load. Primary to experiment for PFRP creep, previous works are studied. In the previous work related to buckling of PFRP member, it can be calculated buckling strength of PFRP members when it is known that material property of longitudinal and transverse direction of PFRP members. The researches for creep behavior of PFRP has been conducted and time-dependent degradation elastic moduls can be predicted by the empirical equation. In this study, it will be conducted creep test for PFRP and time-dependent stress-strain relationship will be plotted. It is expected that long-term buckling behavior of PFRP is evaluated by theoretical and numerical method such as finite element method.
In this study, we investigated the shear properties of pultruded fiber reinforced polymer plastic (PFRP) composites. Especially, we focused on the relationship between the shear properties of PFRP and other mechanical properties of PFRP composites by comparing the experimental results with the theoretical results. We compared the shear characteristics obtained by the tensile test and calculated from the theoretical equation proposed in previous work. It was found that the shear modulus of elasticity predicted by using the theoretical formula is close to the shear modulus of elasticity obtained by the 45° off-axis tensile test.
The pultruded fiber reinforced polymer plastic (PFRP) is one of the most actively studied composite materials for the structural member in construction industries. In domestic design process, the PFRP member is designed as an isotropic material having only longitudinal material properties for simplicity, because it is too complex to consider orthotrophy of PFRP perfectly. In this study, three cases of buckling analysis of PFRP plate is conducted theoretically and numerically. First, the PFRP plate is considered as an orthotropic material. Second, the PFRP plate is considered as an isotropic plate having only longitudinal material properties. Third, the PFRP plate is considered as an isotropic plate having geometric mean of longitudinal and transverse material properties. As a result of buckling analysis, a buckling strength of PFRP plate as an isotropic plate having only longitudinal material properties is about 2.21 times larger than that of PFRP plate analyzed as an orthotropic plate. On the other hand, a buckling strength of PFRP plate as an isotropic plate having geometric mean material properties is about 1.19 times larger than that of PFRP plate analyzed as an orthotropic plate. In conclusion, the safety factor of 3 used in domestic design process of PFRP member is no longer applicable due to overestimation of buckling strength of PFRP member which leads to nonconservative design.
Conventional steel and concrete piles are widely applied in civil engineering industries with long time experience and many advantages. However, steel pipe piles, a sort of most common steel pile, are prone to losing their structural integrity over time due to corrosive and humid conditions. Moreover, concrete piles such as in-situ concrete piles and pretensioned spun high strength concrete (PHC) piles are subject to deterioration of their long-term structural durability. Therefore, Hybrid FRP-concrete composite pile (HCFFT) was developed. HCFFT is consisted of pultruded FRP (PFRP) unit module, filament winding FRP which is in the outside of mandrel composed of circular shaped assembly of PFRP unit modules, and concrete which is casted inside of the circular tube shaped hybrid FRP pile. Therefore, PFRP can increase the flexural load carrying capacity, while filament winding FRP and concrete filled inside can increase axial load carrying capacity. In this paper, field loading experiments were conducted to evaluate field bearing capacity of HCFFT pile with connection and HCFFT pile without connection.
Recently, glass fiber reinforced polymer plastic (GFRP) pipes are increasing trend in using in the water-supply system because of their advantages such as light-weight, corrosion resistance, etc. GFRP pipes discussed in this paper have polymer mortar layer between filament winding glass fiber reinforced polymer plastic layers. So, GFRP pipe properties such as pipe stiffness (PS) and equivalent modulus of elasticity (Eeq ) for the design are complicated to predict or to measure. In this study, we proposed the equation that can predict the equivalent pipe stiffness factor (EI) in relation to PS and Eeq using thickness of each material layer. The predicted result obtained by the equation proposed in this paper is compared with experimental result. As a result, it was in the range of –5% to +2%. Therefore, it is found that the proposed equation can be used to design GFRP pipe used in practice.
A pultruded fiber reinforced polymer plastic (PFRP) structural member consisted of plate elements, which is commonly used as construction member, may be considered as an orthotropic material due to its unique manufacturing process. It has different mechanical properties with respect to the longitudinal and transverse directions. This orthotropic nature of PFRP material needs to be considered in the analysis of buckling behavior. In this paper, a simplified buckling analysis for PFRP plate using geometric mean of the longitudinal and transverse mechanical properties is performed. The comparison between exact buckling analysis and simplified buckling analysis is conducted. Each analysis is performed by the Levy method and the finite element method (FEM), respectively.
In general, polyethylene (PE), polyvinyl chloride (PVC), and ductile cast iron pipes are widely used in the water supply pipeline system. However, they have some disadvantages such as reduced durability due to material degradation, defects in connections, breakage of pipelines, and difficulties in continuous maintenance. To mitigate such problems, recently, research on durable and outstanding corrosion resistant glass fiber reinforced polymer plastic (GFRP) pipe is being actively conducted. GFRP is classified into the flexible pipe and when soil pressure and live load act on buried GFRP pipe, the load acting on the pipe is transferred to the surrounding soil. So, it should review the structural behavior and interaction between buried pipe and its surrounding soil because pipe will support the load with the surrounding soil together at the same time. To apply GFRP pipe for the water supply pipeline system, the structural reliability of GFRP water supply pipe buried underground should be investigated by examining the mechanical properties of GFRP pipe as well as the soundness of the pipe under buried state. The field test of buried pipe is conducted and the results are analyzed and discussed.
Bridge inspection structures are the structure which is installed on the piers, abutments, and copings for the inspection and maintenance of substructure. In this study, the structural performance of the bridge inspection structures using aluminum members manufactured by extrusion process is evaluated. The bridge inspection structures can be installed regardless of the shape of concrete surface through the simple cutting process. The structural performance of bridge inspection structures is evaluated using FE analysis. Moreover, experimental studies are conducted for the estimation of the structural safety of the members for the design load.
Pultruded fiber reinforced polymeric plastic (PFRP) has many advantages such as high corrosion resistance, high specific stength/stiffness, light weight, etc. Pultrusion is a manufacturing process for producing continuous lengths of reinforced polymeric structural shapes with constant cross-section. The mechanical property of PFRP is usually regarded as an orthotropic material. The pultruded structural shapes are usually composed of thin-walled plate element. Because the composite material has relatively low elastic moduli, the design of pultruded compression members may not be governed by the material strength limit state but by the stability limit state such as the local buckling. Therefore, the stability limit state must be checked to design pultruded thin-walled compression members. In this paper, we present the analytical study results of elastic buckling strength of PFRP orthotropic plates with different fiber volume ratios. The local buckling analysis of pultruded compression members was conducted for various composite materials using the closed-form solution. From the study it was found that if E11/E22 is increased then the plate buckling coefficient, hence the plate buckling strength, is decreased.
In the water supply pipeline system, pipes made by cast iron, PE, PVC are generally used. However, the structural performance of these materials can be declined when used for long periodsof time because of corrosion, creep, deterioration of the material, etc. while glass fiber reinforced polymer plastics (GFRP) have many advantages such as light-weight, corrosion resistance, smooth surface, etc. For these reasons, GFRP pipes are good for construction when it is buried underground and are increasing trend in applying the water supply pipeline system. Therefore, more optimized structural design methodology should be developed. In this paper, we confirm pipe stiffness (PS) of GFRP pipe in which the pipe stiffness indicates the load-bearing performance. We compared data of parallel-plate loading test and theoretically predicted PS by the classical elasticity theory and the finite element method (FEM).
In the water supply pipeline system polyethylene (PE), polyvinyl chloride (PVC), and ductile cast iron pipe are mostly used. However, they have some problems such as reduced durability due to material degradation, defects in connections, the pipelines breakage, and lack of continuous maintenance. Recently, research on durable and outstanding corrosion resistance glass fiber reinforced polymer plastic (GFRP) pipe is being actively conducted. GFRP is classified into the flexible pipe and when soil pressure and live load act on buried GFRP pipe, the load acting on the pipe is transferred to the surrounding soil. So, pipe will support the load with the surrounding soil. In this paper, to apply GFRP pipe for the water supply pipeline system, the structural reliability of GFRP water supply pipe buried underground should be investigated by examining the mechanical properties of GFRP pipe as well as the soundness of the pipe under buried state. The field test of buried pipe is conducted and the results are analyzed and discussed.
Generally, antiseptic synthetic woods are used in septic environment because of their durability and relatively fine view. However, they have problems such as a failure of connection between the members under the septic conditions. In this study we investigate a fiber reinforced polyurethane foothold to be used in the wet environment to replace the synthetic wood. The fiber reinforced polyurethane foothold is consist of 2 different layer of materials. First layer is a glass fiber reinforced polymeric plastics (GFRP) which is located at outer surface of the foothold. This GFRP outer layers carry most parts of load. Second layer is a polyurethane layer which transfers the load to each outer layer. Flexural tests for this foothold are conducted. From the flexural tests it is confirmed that the structural performance of foothold test specimen with different number of GFRP layers and density of the polyurethane.
Pipe line for the water supply and/or drainage is one of the most important life lines which is usually suffered from the damage due to exterior load induced deformation and due to the lack of support resistance provided by the surrounding soil. GFRP (Glass Fiber Reinforced Polymer Plastic) pipes are generally thinner, lighter, but stronger than the existing concrete or steel pipes, and it is excellent in stiffness/strength per unit weight. In this study, we present the result of field test for buried RPMP (Reinforced Polymer Mortar Pipe) and RTRP (Reinforced Thermosetting Resin Pipe) pipes with 2,400mm diameter. The vertical and horizontal ring deflections are measured for 387 days. The ring deflection of RPMP and RTRP measured by the field test is compared with the ring deflection limitation (5%) according to ASTM D 2412.
In this paper, we present the result of analytical investigation pertaining to the structural behavior of steel-concrete composite plate girder with arch-type web stiffener. In the arch-type web stiffener located in the compression side of web, infill concrete is cast to strengthen the arch-type stiffener and also to exert resisting force against compression force. This type of composite steel-concrete plate girder bridge is built and is in service. To understand the behavior thoroughly, analytical parametric study was conducted by using the finite element method. As a result it was found that the effect of arch-type stiffener with infill concrete is considerable for the design of such type composite girder bridge.
In this paper, we present the result of investigations pertaining to the elastic buckling of simply supported columns with various cross-sectional dimensions but the same length and volume. In the investigations the accuracy of the analysis methods is studied and it was found that the result obtained by the successive approximations technique is the most accurate. In addition, the elastic buckling loads of columns with variable cross-section dimensions are obtained by the theoretical and numerical methods. From the results, it was found that the buckling loads obtained by the numerical methods are close to the buckling loads obtained by the successive approximations technique for the practical standpoints. Moreover, the buckling load of column with convexity in its middle is the highest while the buckling load of the tapered column is the lowest as expected.