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.

Prestressed concrete (PSC) is a method in which prestressed tendon is placed inside and/or outside the reinforced concrete member and the compressive force applied to the concrete in advance to enhance the engineering properties of concrete member which is weak under tension. In this paper we suggested the precast PSC girder assembled with segments of portable size and weight at the factory. The segments of precast PSC girder will be delivered and assembled as a unit of PSC girder at the site. Consequently, we suggested new-type of precast segmented PSC girder with different shapes of segment cross-section (i.e., I-shape, Box-shape). To mitigate the problems associated with the field splice between the segments of precast PSC girder anchor system is attached near the neutral axis of the girder and relatively uniform compression throughout the girder cross-section is applied. Prior to the experimental investigation, analytical investigation on the structural behavior of precast PSC girder was performed and the serviceability (deflection) and safety (strength) of the girder were confirmed. In addition, 4-point bending test on the girder was conducted to investigate the structural performance under bending. From the experimental investigation, it was found that the precast PSC girder spliced with 3 and 5 segments has sufficient in serviceability and safety conditions and it was also observed that the point where the segments spliced has no defects and the girder behaves as a unit.

Prestressed concrete PSC girders are efficient in terms of structural performance, economical efficiency and constructability. However, PSC girders have overtuning risk in construction in which extra work needs to protect. The low center of gravity girder (MPC girder) is more stable and easier to construct than the traditional PSC girder, which has tweaked end point and mono-tendon anchor. In this study, we evaluated the structural advantages in the deflection (slope) and stress on the link slab by using the finite element method. As a result, it was found that the reinforcement in the link slab for the bridge continuation may be reduced because of less displacement.

FRP members which have light weight, high specific strength and stiffness, and good corrosion resistance are used widely in the electrical transmission system. Recently, FRP instead of steel, wood, and concrete tower is installed and in use. In this paper, we investigated the feasibility of replacement of traditional materials (steel, wood, and concrete) in electrical transmission towers by the fiber reinforced polymer plastic (FRP) members through the literature review. It was found that the FRP electrical transmission towers were applied in many countries due to its various advantages.

In recent years, the Glass Fiber Reinforced Polymer Plastic (GFRP) structural shapes are available in civil engineering applications. Among many manufacturing techniques used for GFRP structural shapes, pultrusion process is one of the most widely used techniques to produce the structural members in civil engineering applications. This study was focused on the mechanical behavior of singly bolted lap-joint connection with various hole clearances (tight-fit: 0.5mm, 1.0mm, 1.5mm, 2.0mm, 3.0mm) in Pultruded GFRP structural members. The specimens with single bolt-hole have been tasted in tension under bolt-loading conditions. The failed specimens were examined for their failure load and fracture patterns with respect to the various hole clearances.

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.

In this paper we present the result of investigations pertaining to the buckling strength of Zelkova Serrata (Elm-like) tree column with entasis at the Muryangsujeon in Buseoksa-Temple, Korea. Wooden columns with entasis had been used in the construction of ancient architectural buildings in Korea. It was not known why did they design columns with entasis of the buildings. It is just presumed that the reason may be the compensation of optical illusion, aesthetics, and/or structural safety. The question is not answered even today and it may not be possible to answer clearly and easily. In the paper, the buckling analyses are conducted on both of the wooden column with entasis and the prismatic wooden column by the successive approximations technique and the finite element methods, respectively. The results of analyses are compared and discussed.

Fiber reinforced plastic (FRP) structural shapes are readily available in civil engineering applications. Among many manufacturing techniques used for FRP structural shapes, pultrusion process is one of the most widely used techniques in civil engineering applications. Pultrusion is a manufacturing process for producing continuous lengths of reinforced polymeric plastic structural shapes with constant cross-section. Pultruded composites are attractive for structural applications because of their continuous mass production with excellent mechanical properties. This paper presents the results of investigations pertaining to the bolted connection with two bolts for the pultruded FRP (PFRP) structural members. PFRP bolted connection tests were conducted with end distance to bolt diameter ratio (e1/db) and two types of bolt pattern such as horizontal (Pattern A) and vertical arrangement (Pattern B). As a result, it is found that the e1/db is recommended as the ratio of 4. In addition, it is also found that the bearing strengths at failure of the Pattern A and Pattern B have a similar value.

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.

Recently, environmental problems associated with the excessive use of fossil fuel are hot issue throughout the world. As an alternative energy resource, the importance of renewable energy is continuously rising. Especially, growth rate of photovoltaic energy generation is one of the best. In this paper, floating PV generation system made of pultruded fiber reinforced polymeric plastic (PFRP) is discussed. It is well known that PFRP has many advantages such as high corrosion resistance, high specific strength/stiffness, etc. Compared with conventional construction materials. To investigate the structural behavior under flow induced dynamic loading, members and connections of members are tested under cyclic loading. It was found that the structural system is strong enough to resist such a cyclic loading.

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.

Pultruded glass fiber reinforced polymeric plastic (PFRP) and FRP member manufactured by sheet molding compound (SMC) have superior mechanical and physical properties compared with those of conventional structural materials. Since FRP has an excellent corrosion-resistance and high specific strength and stiffness, the FRP material may be highly appreciated for the development of floating-type photovoltaic (PV) power generation system. In this paper, advanced floating PV generation system made of PFRP and SMC is designed. In the design, it includes tracking solar altitude by tilting photovoltaic arrays and tracking solar azimuth by spinning structures. Moreover, the results of the finite element analysis (FEA) are presented to confirm stability of entire structure under the external loads. Additionally, installation procedure and mooring systems in the Hap-Cheon Dam are discussed and the measurement of strain under the actual circumstances is conducted for assuring stability of actually installed structures. Finally, by comparison with allowable stress, appropriate safety of structure is confirmed to operate the system.

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.

In recent years, fiber reinforced polymer plastic composites are readily available in the construction industry. Fiber reinforced polymer composite has many advantages such as high specific strength and high specific stiffness, high corrosion resistance, light-weight, magnetic transparency, etc. In this paper, we present the result of investigation pertaining to the flexural behavior of flange strengthened I-shape pultruded fiber reinforced polymer plastic (PFRP) member using carbon fiber sheet (CFRP sheet). Test variable is consisted of the number of layers of strengthening CFRP sheet from 0 to 3. From the experimental results, flexural strengthening effect of flange strengthened I-shape PFRP member using CFRP sheet is evaluated and it was found that 2 layers of strengthening CFRP sheet are appropriate considering efficiency and workability.

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.