• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.13-16
• /
• 2004

The PCS system, which consists of precast concrete column and steel beam, has been developed. The system is expected to achieve the effectiveness in the constructability and improve the structural performance under earthquake. New types of joint system for the panel zon and column connection has been developed in order to improve the shear strength capacity and rigidity of the of the system. The cyclic seismic test recommended by ACI was conducted to verify the structural performance of the system. As a test results, it is observed that the system satisfy most of the requirements by ACI criteria.

• Computers and Concrete
• /
• v.13 no.4
• /
• pp.517-529
• /
• 2014

In order to increase the load carrying capacity and/or increase the service life of existing circular reinforced concrete bridge columns, Carbon Fiber Reinforced Polymer (CFRP) composites could be utilized. Transverse wrapping of circular concrete columns with CFRP sheets increases its axial and shear strengths. In addition, it provides good confinement to the concrete column core, which enhances the bending and compressive strength, as well as, ductility. Several experimental and analytical studies have been conducted on CFRP strengthened concrete cylinders/columns. However, there seem to be lack of thorough investigation of the effect of elevated temperatures on the response of CFRP strengthened circular concrete columns. A concrete confinement model that reflects the effects of elevated temperature on the mechanical properties of CFRP composites, and the efficiency of CFRP in strengthened concrete columns is presented. Tensile strength and modulus of CFRP under hot conditions and their effects on the concrete confinement are the primary parameters that were investigated. A modified concrete confinement model is developed and presented.

• Journal of Korean Association for Spatial Structures
• /
• v.13 no.4
• /
• pp.22-27
• /
• 2013

• Journal of Korean Association for Spatial Structures
• /
• v.12 no.2
• /
• pp.13-17
• /
• 2012

• Magazine of the Korea Concrete Institute
• /
• v.20 no.2
• /
• pp.19-24
• /
• 2008

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.29 no.3
• /
• pp.269-275
• /
• 2016

In this paper, shear performance of concrete wide beams was evaluated through shear failure tests. The specimens were designed to have two continuous spans with a column at the center of the wide beam. Also the specimens were reinforced with plates with openings as shear reinforcements. For the test, total eight specimens, including five specimens were reinforced with steel plates and the other three specimens were reinforced with GFRP plates were manufactured. And the shear strengths obtained from the tests were compared with ones from the equation provided by ACI 318. Support width of wide beam, support section of wide beam and shear reinforcement material were considered as variables. The results showed that the support width was proportional to the increase of shear strength. Also, regardless of material type of shear reinforcement, the shear reinforcing effect was similar when the amount of shear reinforcement was the same.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.11a
• /
• pp.47-52
• /
• 2001

Short reinforced concrete bridge piers are particularly susceptible to shear failure as a consequence of the high shear/moment ratio and conservatism in the flexural strength design of existing RC bridge pier, which were constructed before 1992. In addition, shear failure is brittle and involves rapid strength degradation. Inelastic shear deformation is thus unsuitable fur ductile seismic response. It is, however, believed that there are not many experimental research works fur shear failure of the existing RC bridge pier in Korean peninsula subjected to earthquake motions. The object of this research is to evaluate the seismic performance of existing circular RC bridge piers by the quasi-static test. Existing RC bridge piers were moderate seismically designed in accordance with the conventional provisions of Korea Highway Design Specification. This study has been performed to verify the effect of aspect ratio (column height-diameter ratio). Quasi-static test has been done to investigate the physical seismic performance of RC bridge piers, such as lateral force-displacement hysteric curve, envelope curve etc.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.05a
• /
• pp.941-946
• /
• 2002

Short reinforced concrete bridge piers are particularly susceptible to shear failure as a consequence of the high shear/moment ratio and conservatism in the flexural strength design of existing RC bridge pier, which were constructed before 1992. In addition, shear failure is brittle and involves rapid strength degradation. Inelastic shear deformation is thus unsuitable for ductile seismic response. It is, however, believed that there are not many experimental research works for shear failure of the existing RC bridge pier in Korean peninsula subjected to earthquake motions. The object of this research is to evaluate the seismic performance of existing circular RC bridge piers by the quasi-static test. Existing RC bridge piers were moderate seismically designed in accordance with the conventional provisions of Korea Highway Design Specification. This study has been performed to verify the effect of aspect ratio (column height-diameter ratio). Quasi-static test has been done to investigate the physical seismic performance of RC bridge piers, such as lateral force-displacement hysteric curve, envelope curve etc.

• Computers and Concrete
• /
• v.9 no.2
• /
• pp.133-151
• /
• 2012

This paper presents an analytical procedure for the analysis of high strength steel fiber reinforced concrete members considering the cracking effect in the serviceability loading range. Modifications to a previously proposed formula for the effective moment of inertia are presented. Shear deformation effect is also taken into account in the analysis, and the variation of shear stiffness in the cracked regions of members has been considered by reduced shear stiffness model. The effect of steel fibers on the behavior of reinforced concrete members have been investigated by the developed computer program based on the aforementioned procedure. The inclusion of steel fibers into high strength concrete beams and columns enhances the effective moment of inertia and consequently reduces the deflection reinforced concrete members. The contribution of the shear deformation to the total vertical deflection of the beams is found to be lower for beams with fibers than that of beams with no fibers. Verification of the proposed procedure has been confirmed from series of reinforced concrete beam and column tests available in the literature. The analytical procedure can provide an accurate and efficient prediction of deflections of high strength steel fiber reinforced concrete members due to cracking under service loads. This procedure also forms the basis for the three dimensional analysis of frames with steel fiber reinforced concrete members.

• Geotechnical Engineering
• /
• v.7 no.2
• /
• pp.41-50
• /
• 1991

This study investigated the variation of the threshold strain and pore water pressure response of the coils at high amplitude vibration using resonant column test. As a result of tests, threshold shear strains of soft clay, clean quartz sand and stiff volcanic deposit were turned out to be 1$\times$10-2%, 1$\times$10-3%, 1$\times$10-4% respectively. Also, threshold shear Strain was found to be changed with confining pressure for the clean quartz sand. An increase of pore water pressure with shear strain was not significant within the shear strain 3~4$\times$10-3%, but it was abruptly increased beyond shear strain 1$\times$10-2%.