• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.04a
• /
• pp.840-845
• /
• 1999

In this study, it was experimentally investigated the effectiveness of repair and strengthening methods for RC beams deteriorated under severs enviromental conditions. Polymer cement were employed to restore the sectional loss and aramid fiber-reinforced sheet was used to reinforce the surface subject to tension. Repaired and strengthened reinforced-concrete samples were subjected to loading tests. The tests revealed that the sectional restoration enhanced the loading capability of the sample structures. Additional strengthening with one aramid fiber-reinforced sheet improved 18% of yielding load and 30% of ultimate load of the structure. Reinforcing with two aramid fiber-reinforced sheets brought about an enhancement of 22% of yielding loading and 49% of ultimate load.

• Magazine of the Korea Concrete Institute
• /
• v.11 no.2
• /
• pp.105-113
• /
• 1999

This study was conducted to evaluate the structural behaviors of Aramid fiber sheet reinforced slabs. Seven concrete slabs with $45{\times}8.5{\times}200cm$ were made for this experiment one slab with out being reinforced completely loaded until failure and the maximum load was obtained from this test. 70% of the maximum load was applied to 3 Aramid fiber sheet reinforced slabs after cracking and to the rest of 3 Aramid fiber sheet reinforced slabs without loading and cracking. Test results shows that maximum loading flexural rigidity and ductility for the Araimid fiber sheet reinforced slabs after initial cracking are similar as those for the Armied fiber sheet reinforced slabs without loading and cracking.

• Journal of the Korea Concrete Institute
• /
• v.24 no.4
• /
• pp.473-480
• /
• 2012

In order to develop an effecive seismic strengthening metghod for existing concrete structure, structural tests of aramid FRP reinforced RC columns are performed. The test variables were strengthening methods of aramid sheet and strip. The test results were evaluated by comparing strength and energy dissipation capacities of non-reinforced and reinforced specimens. The test result comparison showed that aramid sheet reinforcement on RC column was evaluated as the most efficient way to increase strength and energy dissipation capacity.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.6
• /
• pp.201-210
• /
• 2023

This study is to evaluate the ductility strengthening effect of aramid fiber sheets on piloti-type structures. Two piloti-type structure specimens were prepared and tested under statical cyclic lateral loads. The ductility strengthening effect was validated from the analysis of lateral load-displacement relationship, displacement ductility ratio, work damage index and torsion behavior. Test results showed that the post-peak behavior of piloti-type structures with columns strengthened with aramid fiber sheets tended to be ductile resulting from preventing shear failure and minimizing torsion due to the effective lateral confinement of column concrete by aramid fiber sheet. Consequently, the displacement ductility ratio and work damage index of piloti-type structures with columns with strengthened with aramid fiber sheets were 4.63 and 42.81 times higher than those of non strengthened piloti-type structures.

• Journal of Ocean Engineering and Technology
• /
• v.13 no.3B
• /
• pp.56-64
• /
• 1999

An experimental study was carried out to examine the structural behavior of reinforced concrete deep beams strengthened with aramid fiber sheets, carbon fiber sheets and plates, and to propose the reasonable strengthening method for the deteriorated R.C. deep beams. Results show that the most significant differences in behavior of reinforced concrete deep beams strengthened with fiber sheet and plate were mainly due to various fiber orientations and anchorage. Deep beams diagonally strengthened with carbon fibers show better performance compared with those of vertically, horizontally strengthened specimens and produce the increase in the shear resistance through the redistribution of internal forces after the initial cracks occur. However, strengthened deep beams without anchorages might show unreasonable, brittle peeling-off failure of fiber reinforcements.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.705-708
• /
• 1999

Advanced composite materials such as carbon fiber, aramid, and glass fiber sheet, are widely used recently to strengthening existing reinforced concrete structures. The purpose of this paper was to investigate the mechanical characteristics of concrete compressive members confined with carbon fiber sheet and evaluate the efficiency of the strengthening under load actions. Uniaxal compression tests of concrete compressive members confined with carbon fiber sheet were experimentally used to develop a relationship between the axial stresses and the lateral stresses. The resulting axial and lateral strains were used to determine the confinement effect of concrete compressive members.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.19 no.5
• /
• pp.112-119
• /
• 2015

In this paper, the strengthening method was proposed for improving the seismic performance of the vulnerable structural frames. To improve the brittle characteristics of columns, aramid fiber sheet was used for the lateral confinement of columns. And to introduce the energy dissipation capacity, a steel damper with S-shaped struts was installed. By making the unreinforced and reinforced specimens with full size specimens were evaluated for lateral load resistance capacity. It was confirmed the strengthening effects by the evaluation of failure shape, strength, stiffness degradation, and energy dissipation capacity. Also from the FE analysis using ABAQUS, the hysteretic behavior of the specimens were predicted and evaluated.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.04a
• /
• pp.743-749
• /
• 1999

Recently new rehabilitation techniques have been proposed with advanced composite materials like carbon fiber, aramid, glass fiber sheet and so forth. The purpose of this paper is to investigate the mechanical characteristics of reinforced concrete columns confined with carbon fiber sheet and evaluate the degree of their strengthening effect. For the test, the specimen size of column is 15cm$\times$15cm$\times$90cm reinforced with 4 number of main bars of 10 mm diameter, tied bars of 6 mm diameter and slenderness ratio 20. Columns were wrapped with carbon fiber sheet along the column length. It is necessary to make some assumption regarding the confinement of carbon fiber sheet to apply to reinforced concrete columns under concentric loads. The strength gain effect of columns confined with carbon fiber sheet could be predicted using the proposed equation.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.10a
• /
• pp.609-614
• /
• 1997

Recently, many researchers have performed R&D about strengthening of R/C with steel plates, carbon fiber sheets. aramid fiber sheets and glass fiber sheets, and so on. However most of research were limited in study of flexural strengthening of R/C beams. This paper shows the results of an experimental study on shear reinforcement of deep beams using Glass Fiber Sheet in relation to shear-span ratio. strengthening orientation and anchorage. The results prove that shear failure is governed by reinforced orientation. adherence and anchorage. Additional anchorage of fibers does not only cause the improvement in the internal resistance, but also control the brittle shear failure of specimen after reaching the maximum load.

• Journal of the Korean Society of Safety
• /
• v.14 no.1
• /
• pp.129-140
• /
• 1999

This study presents test results of RC beams strengthened by steel plates, carbon fiber sheets(CFS) and aramid fiber sheets(AFS) for increasing flexural and shear resistance. The test was performed with different parameters including the type of strengthening materials, flexural-strengthening methods and shear-strengthening methods. In case of flexural test, RC beams are initially loaded to 70% of the ultimate flexural capacity and in case of shear test loaded to 60 or 80 percent of the ultimate shear capacity and subsequently reinforced with steel plates, CFS and AFS. Experimental data on strength, steel strain, deflection, and mode of failure of the reinforced beams were obtained, and comparisons between the different shear reinforced schemes and the non-strengthened control beams were made. The test results showed that damaged RC beams strengthened by steel plates, CFS and AFS have more improved the flexural and shear capacity. For the beams with external reinforcement by steel plates, aramid fiber sheets and carbon fiber sheets increases in ultimate strength of 4 to 21, 17 to 43 and 26 to 36 percent were respectively achieved. Initial load had small effect on strength after reinforcement, but an important influence on deflection. One sheet reinforced was stronger than two sheets reinforced but less deflected than two sheets reinforced.