In this study, we suggested the jacking method of small diameter sewer pipe for improving workability of the pipe at the weak ground. The jacking method minimizes the space and time in constructing small diameter sewer pipe. In addition, to use this method do not cause road restrictions during the construction period. In this study, the construction process of the small diameter sewer pipe is explained. In addition, to ensure the safety during construction, the design consideration such as earth pressure and the jacking force of the steel pipe, and safety against boiling of the ground were examined. For verify the safety of this jacking method, it is necessary to carry out an experiment to estimate the safety of main pipe under construction.

Floating PV generation system, renewable energy power plant, is able to overcome the disadvantages of ground PV generation system and improve generating efficiency. The frame structural system is an established technology among a diversity of structural technologies which has been developed for related fields. In this paper, the both structural safety and characteristics of floating PV generation structures depend on the different placement angle of solar module are investigated to improve the commercial viability, the structural safety, and characteristics of floating PV generation structures. In addition, for the estimation of structural safety, FE analyses are conducted. From the results, the lower placement angle of solar module improves the structural safety of floating PV generation system.

In this paper, the full-size structural performance test for a lightweight soundproof tunnel composed of partitioned pipe truss members is carried out to investigate the structural performance. In addition, a nonlinear structural analysis of the same finite element model as the full-size testing model is performed to compare the test result. The test and analysis results showed that the lightweight soundproof tunnel ensures the structural safety against wind loads, snow loads and load combinations. As a result, the full-size test and analysis results m

GFRP (glass fiber reinforced polymeric plastic) composite members are superior construction materials because they have higher specific strength and stiffness than steel and concretes. In addition, they also have high resistance to chemical corrosion. However, in many existing researches it reported that GFRP members have less resistance to ultra-violet ray (UV-ray), so they may cause critical structural problems due to changes of mechanical properties when the material is long-term exposed under UV-ray. In this study, we investigated whether these reports are reliable through two processes. First, we reviewed existing researches on the FRP members’s resistance to UV-ray, and then we conducted tensile strength test for GFRP sample exposed to UV-ray for 30 months (900 days). These two processes showed that mechanical properties of GFRP members do not change under long-term UV-ray exposure and they have enough resistance to UV-ray.

Due to rapid urbanization and industrialization, water supply and sewer line systems are also developed relevantly. Manhole is an essential component structure of the pipeline system. Manhole is a structure constructed to accommodate the direction, dimension, differences in level, and easy of maintenance in the pipeline system. In this paper we present the result of investigations pertaining to the structural behavior of PVC sewer manhole buried underground. In the paper mechanical properties of PVC material are reported. In addition, by the finite element analysis (FEA), we confirmed that a PVC double-wall corrugated pipe manhole, when it is buried underground, is safe for the stress as well as buckling strength if the manhole is constructed within the suggested limit of buried depth.

Fiber reinforced polymeric plastic (FRP) materials have many advantages over conventional structural materials, i.e., high specific strength and stiffness, high corrosion resistance, right weight, etc. Among the various manufacturing methods, pultrusion process is one of the best choices for the mass production of structural plastic members. Since the major reinforcing fibers are placed along the axial direction of the member, this material is usually considered as an orthotropic material. However, pultruded FRP (PFRP) structural members have low modulus of elasticity and are composed of orthotropic thin plate components the members are prone to buckle. Therefore, stability is an important issue in the design of the pultruded FRP structural members. Many researchers have conducted related studies to publish the design method of FRP structures and recently, referred to the previous researches, pre-standard for LRFD of pultruded FRP structures is presented. In this paper, the accuracy and suitability of design equation for the local buckling strength of pultruded FRP I-shape compression members presented by ASCE are estimated. In the estimation, we compared the results obtained by design equation, closed-form solution, and experiments conducted by previous researches.

Glass fiber reinforced thermosetting polymer plastic (GRP) is widely used in the construction industries due to the advantages of their superior mechanical and physical characteristics. Most of pipes are installed for long-term purposes and they should be safely installed in consideration of installation conditions because there are unexpected various terrestrial loading conditions. In this paper, we present the result of investigation for 253 days pertaining to the structural behavior of flexible pipes buried underground. From the buried test results, we predicted long-term, up to 60 years, ring deflection of GRP pipes buried underground based on the method suggested by the existing literature. It was found that the GRP flexible pipe is appropriate because 5% ring deflection limitation of 60 years could be satisfied.

Pultruded FRP can be regarded as an orthotropic material due to its manufacturing process that pull-out fibers impregnated with polymeric resin, which is suitable to produce structural member with unlimited lengths of reinforced polymer structural shapes with a various shape of cross-section. However, fiber distribution in the cross-section is not uniform because of the characteristics of pultrusion process. Therefore, random fiber distribution causes the difference of the modulus of elasticity throughout the cross-section. In this paper, closed-form local buckling analysis is conducted on the pultruded FRP I-shape compression members. The mechanical properties used to analytical investigations are obtained from the coupon test. The coupon test specimens are taken from the pultruded FRP I-shape member. Moreover, the local buckling tests of pultruded FRP I-shape members are conducted and test results are compared with the analytical results.

The floating PV generation structure installed on the surface of water has been recently issued as a representative items for the low carbon and green growth campaign. Moreover, the studies and developments for the structure and construction improvements of floating PV generation structure have been in progress. For example, in the previous research, the floating PV generation structure consisted of pultruded FRP and SMC FRP members is suggested. In this study, we conduct the analytical and experimental studies for estimating the structural characteristics of SMC FRP vertical members. From the analytical and experimental results, it is found that SMC FRP vertical members used for floating PV generation structure have sufficient structural safety and stability.

Pile foundations constructed by the fiber reinforced polymer plastic piles have been used in coastal and oceanic regions in many countries. Generally, fiber reinforced polymer plastic piles are consisted of filament winding FRP which is used to wrap the outside of concrete pile to increase the axial load carrying capacity or pultruded FRP which is located in the core concrete to resist the bending moment arising due to eccentric loading. In this paper, the analytical procedures of hybrid concrete filled FRP tube flexural members are suggested based on the CFT design method. Moreover, the analytical results are compared with the experimental results to obtained by the previous researches. The results of comparison analyses are performed to estimate the accuracy of the analytical procedure for hybrid FRP-concrete composite compression test, members under eccentrical loading.

Glass fiber reinforced plastic (GRP) pipes buried underground are attractive for use in harsh environments, such as for the collection and transmission of liquids which are abrasive and/or corrosive. In this paper, we present the result of investigation pertaining to the structural behavior of GRP flexible pipes buried underground. In the investigation of structural behavior such as a ring deflection, experimental and analytical studies are conducted. In addition, vertical ring deflection is measured by the field test and finite element analysis (FEA) is also conducted to simulate behavior of GRP pipe buried underground. Based on the results from the finite element analyses considering soil-pipe interaction the vertical ring deflection behavior of buried GRP pipe is predicted. In addition, analytical and experimental results are compared and discussed.

HCFFT (Hybrid Concrete Filled FRP Tube) is consisted of pultruded FRP unit module, filament winding FRP which is in the outside of mandrel composed of circular shaped assembly of pultruded FRP unit modules, and concrete which is casted inside of the circular tube shaped hybrid FRP pile. The pultruded FRP can increase the flexural load carrying capacity and the filament winding FRP can provide the confinement for the concrete filled inside. The axial and flexural load carrying capacities of small diameter HCFFT piles were evaluated through the experimental and theoretical studies. In this study, we suggest the cross-section and manufacturing process of large diameter HCFFT pile which is expected to improve the quality and productibility of large diameter HCFFP pile.

Carbon fiber reinforced polymeric plastic (CFRP) can be used for the deteriorated reinforced concrete members. CFRP reinforcement method, which is one of the reinforcement methods, can improve the strength and durability of reinforced concrete member. CFRP reinforcement method has been proved that it has sufficient effect on the flexural strengthening of reinforced concrete flexural member through numerous previous researches. In this paper, we present the analytical result of investigation pertaining to the CFRP reinforcing effect on the singly reinforced and doubly reinforced rectangular flexural members and T-shape singly reinforced flexural member. The analytical study is performed according to the code by ACI Committee 440 and previous research results.

GRP (Glass fiber reinforced polymer plastic) pipes are classified into flexible pipe category because of the structural characteristics of GRP pipes buried underground. Moreover, the ring deflection of GRP pipe is affected by the certain factors such as pipe stiffness, the modulus of soil reaction of backfill materials, and bedding conditions. In this study, we investigated the structural characteristics of the GRP pipes buried underground considering the soil-pipe interaction including bedding angle, pipe stiffness, and soil density used as a backfill material. From this parametric study, it was found that the soil density used for the backfill is the most important factor relating to the ring deflection of the buried GRP pipe.

Pultruded FRP (Pultruded Fiber Reinforced Polymeric Plastic, PFRP) members have many advantages such as high strength and stiffness, high corrosion resistance, light weight, etc. However, it has relatively low modulus of elasticity and also cross-section of the structural shapes is composed of thin plate components. Therefore, global buckling, local buckling, and post-buckling strengths should be considered in the design of compression members. In the structural steel design following AISC/LRFD, this effect, in addition to the buckling strength, is incorporated with a form factor. In this study, referring to AISC/LRFD, form factor for the design of I-shape and Box-shape PFRP members under compression has been suggested and discussed through the analytical study.

Concrete filled FRP tubes (CFFT) and reinforced concrete filled FRP tubes (RCFFT) are known to have the capability to enhance structural performance in terms of structural stability, ductility, as well as chemical resistance when compared with conventional concrete members. In this study, we evaluate the structural performance of the CFFT and the RCFFT through flexural tests for the purpose of applying the members as flexural ones. The degree of improvement on the flexural performance of the RCFFT member strengthened by the FRP was analyzed from the flexural tests.

펄트루젼 FRP 구조용 부재는 많은 유용한 역학적, 물리적 성질 때문에 토목분야에서 구조부재의 매력적인 대체부 재로 고려될 수 있다. 그러나 펄트루젼 FRP는 탄성계수가 상대적으로 낮고, 부재의 단면이 복부와 플렌지 등의 얇 은 판요소로 구성되어 있기 때문에 압축재로 설계할 때 구조적인 안정성은 매우 중요한 고려사항이 된다. 따라서, 압축을 받는 구조용 부재의 설계를 위해, 판요소의 좌굴 및 후좌굴강도를 고려해야 한다. AISC/LRFD의 강구조 설 계기준에서는, 후좌굴강도에 추가적인 단면 내 일정하지 않은 응력분포의 영향을 형상계수(form factor)를 사용하여 고려하고 있다. 이 논문에서는 압축력을 받는 펄트루젼 FRP 구조용 부재의 형상계수를 해석적으로 연구하였으며, 형상계수를 설정하는 과정에 대하여 제안하였다.

이 논문는 펄트루젼 FRP 부재를 이용하여 부유식 태양광발전 시스템을 개발하기 위한 연구의 결과이다. 이미 설치 된 부유식 태양광발전 시스템의 단위구조물에 추가적인 단위구조물의 연결을 위하여 연결부를 설계하여 유한요소 해석을 통한 검증을 실시하였으며, 실제 현장에 기존 단위구조물과 연결부를 포함한 단위구조물의 연결부를 성공적 으로 시공하였다. 또한 기존 설치 구조물의 현장계측을 통하여 변위와 변형률을 얻어 기존의 실험 결과와 비교하여 구조물이 충분히 안전함을 확인하고 이를 바탕으로의 부유식 태양광발전 시스템의 설계 변경을 실시하였다. 설계변 경된 구조물에 대한 유한요소해석을 실시하였고 이를 허용응력과 비교하여 안전성을 검증하였다. 이로써 더욱 효율 적인 구조물을 개발하였으며 구조물의 제작하였다. 설계 변경된 단위구조물의 제작을 위한 펄트루젼 FRP부재의 생 산하였으며, 부유식 태양광 에너지 발전시설 구조물을 조립하였다.

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 usually 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. The load carrying capacity of proposed RCFFT compression member is discussed based on the result of experimental and analytical investigations.