• Journal of Welding and Joining
• /
• v.6 no.1
• /
• pp.28-34
• /
• 1988

The fatigue test was carried out to evaluate the fatigue characteristics of the accelerated cooled (ACC) TMCP steel and its welded joint. From this study, it was confirmed that ACC TMCP steel has higher fatigue strength than conventional steels. After welding, however, the fatigue strength of ACC TMCP steel was deteriorated associated with HAZ softening when weld reinforcement was removed. On the other hand, with weld reinforcement, there is no effect of HAZ softening on the fatigue strength of welded joint because it is strongly dependant on the detail weld geometry i.e., stress concentration factor. Accordingly the fatigue strength of actual welded joint increases with decreasing the stress concentration factor of welded joint, regardless of HAZ softening.

• Journal of the Korean Institute of Rural Architecture
• /
• v.7 no.1
• /
• pp.121-128
• /
• 2005

This experimental study was conducted to investigate beam strengthening of RC buildings with expended steel plate(ESP) in rural area. Nine test specimens were manufactured, whose variables were tensile steel ratio and the amount and the shape of expanded steel plate. The test results indicated that strengthened beams with ESP showed the improvement of flexural strength of 50%~90%, and the beam strengthening of U type was excellent for shear reinforcement as well as flexural reinforcement, more over, the honeycomb shape of ESP and anchor bolts for development of ESP were very effective.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.11a
• /
• pp.71-76
• /
• 2000

In generally, grouting consists of injecting a suspension or solution into the voids of soils. The low slump mortar grout has been used in America since 1950's. The Compaction Grouting, the injection of a very stiff under relatively high pressure, form a cylinderical grout support pile. The grout generally does not enter soil pores but remains in homogeneous mass that gives controlled displacement either to compact loose soils, or for lifting of structures, or both. In this paper, on the case of the reinforcement construction of 00 plant that the foundation's bearing capacity is insufficient and is to reinforce the foundation, a study has been peformed to analyze the effectiveness of the ground improvement. The bearing capacity of the Compaction Pile has been verified by the S.P.T and the settlement of the improved ground has been monitored rising the magnetic extensometer.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.04a
• /
• pp.639-644
• /
• 2000

Prestressing steels are susceptible to corrosion, which is considered the major reason in the deterioration of prestressed concrete structures. To solve this problem, many research have been made to utilize new type of tendons. FRP tendons have many advantages compared to steel tendons. However, FRP tendons have some disadvantages, such as no plastic behavior. This study focused on the flexural behavior of prestresssed concrete beams which is fabricated by post-tensioning method with CFRP (Carbon Fiber Reinforced Plastic) tendons. Th results drawn from the study, prestressed concrete beams with CFRP tendons have higher flexural cracking load, flexural yielding load, and flexural fracture load. While displacement at the fracture stage is lower compared to prestressed concrete beams with steel tendon. Excessive steel reinforcement lead lower ductility index. So, appropriate reinforcement guideline is needed. Further more, prestressed concrete beams with CFRP tendons can have sufficient ductility index when ruptured by crushing of concrete or used unbonded tendon. Therefore, the best design method for prestressed concrete beams with CFRP tendons is over-reinforcement, and use of unbonded tendon.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.45 no.2
• /
• pp.58-67
• /
• 2003

Over the last decade fiber-reinforced polymer (FRP) reinforcement consisting of glass, carbon, or aramid fibers embedded in a resin such as vinyl ester, epoxy, or polyester has emerged as one of the most promising and affordable solutions to the corrosion problems of steel reinforcement in structural concrete. But reinforcing rebar for concrete made of FRP rebar has linear elastic behavior up to tensile failure. For safety a certain plastic strain and an elongation greater than 3% at maximum load is usually required for steel reinforcement in concrete structures. The same should be required for FRP rebar. Thus, the main object of this study was to develop new type of hybrid FRP rebar Also, this study was evaluated to the mechanical properties of Hybrid FRP rebar. The Manufacture of the hybrid FRP rebar was achieved by pultrusion, and braiding and filament winding techniques. Tensile and interlaminar shear test results of Hybrid FRP rebar can provide its excellent tensile strength-strain behavior and interlaminar stress-strain behavior.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2001.10a
• /
• pp.75-82
• /
• 2001

Finite element analysis using ANSYS program conducted to evaluate the tensile behavior of the connection between reinforced concrete and steel members is presented in this paper. It is assumed that there is a complete bond between head part of the stud and concrete. However, the surface of the column area of stud is separated from the concrete to stop the stress transmission between those. In case of using reinforcement connectors such as C or U type, the interface between concrete and reinforcement is idealized to have strong adhesion. Four concrete-steel specimens which are connected by stud connector or reinforcement connectors are compared and analyzed From the comparison, it was shown that the connection between concrete and steel could be predicted by using the modeling technique used in this paper.

• Nuclear Engineering and Technology
• /
• v.54 no.6
• /
• pp.2156-2172
• /
• 2022

This paper investigates the optimum fiber reinforcement for prestressed concrete containment vessels (PCCVs) under internal pressure. To achieve this aim, steel fiber, which is the most widely used fiber type in current engineering applications, is adopted to constitute steel fiber-reinforced concrete (SFRC) to substitute the conventional concrete in the PCCV. The effects of characteristic parameters, 𝜆_sf, of the steel fiber affecting significantly the mechanical behavior of the concrete are first taken into account. Partial or complete concrete regions of the PCCV are also considered to be replaced by SFRC to balance the economy and safety. By adopting the ABAQUS software, the ultimate bearing capacity and performance for the fiber-reinforced PCCV are scientifically studied and quantified, and the recommendations for the optimum way of fiber reinforcement are presented.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.1
• /
• pp.103-111
• /
• 2011

This paper estimated the structural behavior of recycled aggregate concrete confined with spiral reinforcement. The main test parameter was designed to be the type of aggregates and the steel ratio of spirals. A total of 18 specimens were cast and tested in this study. All the specimens had a diameter of 150mm and a height of 300mm. The specimens can be divided into two groups, based on the type of coarse aggregate used. The ratio of spiral reinforcement was varied from 0 % to 1.75%. To measure the axial and lateral deformations of the specimens, a total of six linear variation displacement transducers (LVDTs) were installed at each specimen. Furthermore strain gauges were also attached to the steel spirals to obtain the strain of spiral reinforcements. From the experimental results, the structural performance of recycled aggregate concrete specimens confined by steel spirals was similar to that of natural aggregate concrete specimens regardless of the ratio of spiral reinforcement.

• Journal of the Korean Geotechnical Society
• /
• v.25 no.2
• /
• pp.5-15
• /
• 2009

The conventional reinforced earth retaining wall has the connector system to fix the reinforcement and block. However, this system defect may cause the crack of block and the rupture of reinforcement due to the stress concentration near the face of reinforced earth retaining wall. Hence, the new connector system which was able to allow the settlement of reinforcement was developed in this study and a test was carried out in the study area which is divided into the conventional reinforced earth retaining wall and reinforced Earth Retaining Wall driving the settlement. As the results of field monitoring in situ, the ratio of tensile force calculated at maximum value on contiguous portion of front block showed that the settlement type decreased the stress concentration near the face of front block greater than the conventional type.

• Composites Research
• /
• v.15 no.4
• /
• pp.17-22
• /
• 2002

Small diameter composite helical springs (CS) are developed using a hot plated mold for reinforcement of common optical fiber jumper cord (OJC). The outer diameters of the springs are about 2 ~ 3mm. These springs are inserted into the OJC to protect the damage of an optical fiber from the sudden lateral load. Two types of CS, Yarn type (Y-type) and Band type (B-type), are manufactured to compare the effectiveness for the damage protection. The experimental works were conducted to check the effect of the CS covered around OJC on the mechanical and optical properties. Experimental observations show a considerable effect on the flexural resistance, hence slowing down the deterioration of the optical power by the internal damage of the fiber. Obtained main results are as follows: (1) Y-type CS has better protection abilities to lateral loading than B-types. (2) Compared with bare OJC, CS-OJC has less power loss under the loading. (3) OJC covered with the composite coil spring has a possibility for a practical usage with full fruits.