• Structural Engineering and Mechanics
• /
• v.27 no.5
• /
• pp.589-607
• /
• 2007

Two series of tests were conducted to investigate the behavior of local thin jacketing for the retrofitting of reinforced concrete (RC) columns. In the first series, four full-scale RC columns with a height of 400 cm and a 30 cm square cross-section were tested under constant axial load and reversed cyclic lateral displacements. The heavily damaged columns were retrofitted with local thin jacketing. Self-compacting concrete (SCC) was used in the production of 7.5 cm thick, four-sided jacketing. The height of the jacketing was 100 cm for one specimen and 200 cm for all others. In the second series, the retrofitted columns were retested with the same axial load and displacement history. The effectiveness of local thin jacketing in the retrofitting of RC columns was examined with respect to lateral strength, stiffness, inelastic load-deformation behavior and energy dissipation.

• Journal of Korean Academy of Nursing
• /
• v.28 no.1
• /
• pp.70-80
• /
• 1998

This study is designed to contribute to the nursing intervention of adolescent domestic violence victims by describing specifically what they go through and on this basis work out a grounded theory on the adolescent's experience in domestic violence. The data were analyzed in the framework of grounded theory as mapped out by Strauss & Corbin(1990). The major findings of this research are as follows : The core category was found to be the the adaptation of "Joyudeum" or “Straight jacketing”. The sub-categories identified in the process of grounded data analysis were 'menacing', 'being harassed', 'being pressed', 'being attacked', 'being strapped', 'being filled with anger'. 'getting angry', 'being oppressed', 'being strained', 'becoming hard', 'endurance', 'regulation', 'seriousness'. 'repitition'. 'being helpful', 'dependence', 'thinking oriented', 'blowing off', 'going astray', 'self-deprecating', 'shaking off', 'covering up', 'governing', 'being devoted', 'performing', 'being transformed'. 'bolting', 'being shaken', 'withdrawing', 'disliking', 'bitterness'. These categories were again grouped into 13 categories including 'threatening'. 'straight jacketing', 'tolerance', 'violence', 'supporter', 'supporting type', 'thinking oriented'. 'impulsive response', 'self-controlled', 'response', 'self-reliance', 'wandering', 'withdrawal' and pain'. Of these the five sub-categories 'being filled with anger'. 'getting angry', 'being oppressed', 'being strained', 'becoming hard' were grouped into a core category "straight jacketing". Those adolescents brought up in a violent family go through three stages of the adaptation of "straight Jacketing". that is, generation, response and adaptation. The following four theses were confirmed on the basis of repetitive relations : 1) If a subject's tolerance is strong, the episodes of the violence are frequent and serious, with the resulting straight jacketing being stronger but the subject's supporter is highly mature, the supporting type is concrete and the thinking oriented is wishful, the responses to the straight jacketing result in a self-control whose consequence is self-reliance with part of it resulted in withdrawal and pain. 2) If a subject's tolerance is weak, the episodes of the violence are frequent but not serious, with the resulting straight jacketing being weaker but the subject's supporter is immature, the supporting type is superficial and the thinking oriented is extemporary, the responses to the straight jacketing result in an impulsion whose consequence is wandering with part of it resulted in withdrawal and pain. 3) If a subject's tolerance is weak, the episodes of the violence are frequent and serious, the straight jacketing is strong, the subject's supporter is immature and the supporting type is superficial but the thinking oriented is wishful, the responses to the straight jacketing result in an impulsion whose consequence is withdrawal and pain with part of it resulted in wandering. 4) If a subject's tolerance is strong and the episodes of the violence are infrequent and not serious, the straight jacketing is weak, the subject's supporter is immature and the supporting type is superficial but the thinking oriented is wishful, the responses to the straight jacketing result in a self-control whose consequence is withdrawal and pain with part of it resulted in self-reliance.

• Progress in Superconductivity and Cryogenics
• /
• v.5 no.1
• /
• pp.71-75
• /
• 2003

The conduit fer superconducting cable is welded and plastically deformed during the jacketing process to make the CICC (Cable-in-Conduit-Conductors) fer a fusion magnet. The jacketing process of KSTAR (Korea Superconducting Tokamak Advanced Research) conductors is composed of several sequential steps such as rounding, welding, sizing, and square-rolling. Since the welded zone in Incoloy 908 conduit is brittle and easy to have flaws, there may be a possibility of stress corrosion cracking during the heat treatment of coil when both the induced tensile residual stress and the concentration of oxygen in the furnace are sufficiently high. The steps of the jacketing process were simulated using the finite element method of the commercial ABAQUS code, and the stress distribution in the conduit in each step was calculated, respectively. Furthermore, the variations of residual welding stresses through the steps of the jacketing process were calculated and analyzed to anticipate the possibility of the stress corrosion cracking in the conduit. The concentrated high tensile residual welding stresses along the welding bead decrease by the plastic deformation of the following sizing step. The distribution in residual stresses in the conductor for magnet coil is mainly governed by the last step of square-rolling.

• Journal of Korean Association for Spatial Structures
• /
• v.22 no.2
• /
• pp.29-37
• /
• 2022

The collapse of reinforced concrete (RC) frame buildings is mainly caused by the failure of columns. To prevent brittle failure of RC column, numerous studies have been conducted on the seismic performance of strengthened RC columns. Concrete jacketing method, which is one of the retrofitting method of RC members, can enhance strength and stiffness of original RC column with enlarged section and provide uniformly distributed lateral load capacity throughout the structure. The experimental studies have been conducted by many researchers to analyze seismic performance of seismic strengthened RC column. However, structures which have plan and vertical irregularities shows torsional behavior, and therefore it causes large deformation on RC column when subjected to seismic load. Thus, test results from concentric cyclic loading can be overestimated comparing to eccentric cyclic test results, In this paper, two kinds of eccentric loading pattern was suggested to analyze structural performance of RC columns, which are strengthened by concrete jacketing method with new details in jacketed section. Based on the results, it is concluded that specimens strengthened with new concrete jacketing method increased 830% of maximum load, 150% of maximum displacement and changed the failure modes of non-strengthened RC columns.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.22 no.5
• /
• pp.281-289
• /
• 2018

Existing reinforced concrete building structures have seismic vulnerabilities due to their seismically-deficient details resulting in non-ductile behavior. The seismic vulnerabilities can be mitigated by retrofitting the buildings using a fiber-reinforced polymer column jacketing system, which can provide additional confining pressures to existing columns to improve their lateral resisting capacities. This study presents dynamic responses of a full-scale non-ductile reinforced concrete frame retrofitted using a fiber-reinforced polymer column jacketing system. A series of forced-vibration testing was performed to measure the dynamic responses (e.g. natural frequencies, story drifts and column/beam rotations). Additionally, the dynamic responses of the retrofitted frame were compared to those of the non-retrofitted frame to investigate effectiveness of the retrofit system. The experimental results demonstrate that the retrofit system installed on the first story columns contributed to reducing story drifts and column rotations. Additionally, the retrofit scheme helped mitigate damage concentration on the first story columns as compared to the non-retrofitted frame.

• Journal of Korean Association for Spatial Structures
• /
• v.23 no.2
• /
• pp.79-90
• /
• 2023

Existing reinforced concrete (RC) frame buildings have seismic vulnerabilities because of seismically deficient details. In particular, since cumulative damage caused by successive earthquakes causes serious damage, repair/retrofit rehabilitation studies for successive earthquakes are needed. This study investigates the repair effect of fiber-reinforced polymer jacketing system for the seismically-vulnerable building structures under successive earthquakes. The repair modeling method developed and validated from the previous study was implemented to the building models. Additionally, the main parameters of the FRP jacketing system were selected as the number of FRP layers associated with the confinement effects and the installation location. To define the repair effects of the FRP jacketing system with the main parameters, this study conducted nonlinear time-history analyses for the building structural models with the various repairing scenarios. Based on this investigation, the repair effects of the damaged building structures were significantly affected by the damage levels induced from the mainshocks regardless of the retrofit scenarios.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.10a
• /
• pp.589-596
• /
• 1998

Experimental studies are investigated for RC column retrofitting under cyclic load. Design considerations are jacketing of steel plate of carbon fiber with epoxy bonding, use of unbonded plate, additional concrete grouting, ratio of additional longitudinal steel reinforcement and longitudinal configuration of additional ties. Investigated results are 1) jacketing and additional reinforcements are effective for strengthening, 2) use of additional grouting is less effective with respect to increased section. Future studies are needed to evaluate the requirements about additional reinforcements for member stress level, 3) bond between original and additional grout concrete.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07a
• /
• pp.244-247
• /
• 2002

In order to evaluate the water ingress to URD power cables with the jacketing materials and the cable structures, water vapor transmission (WVT) tests were carried out by the ASTM and the TEPCO's specification. All polyolefin compounds showed the superior water suppression to conventional PVC. Especially, linear polyethylenes have very low WVT. In case of cable structures, Allaminate cables showed the significant water suppression due to the watertight structure. Accordingly, it can be concluded that jacketing material and cable structure play an important role in the water suppression of URD power cables.

• Journal of Korean Association for Spatial Structures
• /
• v.21 no.2
• /
• pp.57-66
• /
• 2021

This study develops finite element models for seismically-deficient reinforced concrete building frame retrofitted using fiber-reinforced polymer jacketing system and validates the finite element models with full-scale dynamic test for as-built and retrofitted conditions. The bond-slip effects measured from a past experimental study were modeled using one-dimensional slide line model, and the bond-slip models were implemented to the finite element models. The finite element model can predict story displacement and inter-story drift ratio with slight simulation variation compared to the measured responses from the full-scale dynamic tests.

• Journal of the Korea Institute of Building Construction
• /
• v.18 no.2
• /
• pp.99-107
• /
• 2018

The objective of the present study is to propose a reliable shape of supplementary V-ties in the section jacketing approach for seismic strengthening of reinforced concrete columns. A total of 24 pull-out specimens were prepared. The test parameters selected with regard to bond strength of V-ties were the shape of V-ties, embedment length of V-tie legs, and compressive strength of concrete. The measured bond strength of V-ties with different shapes were compared with that of the conventional V-ties and predictions using CEB-FIP equation. Ultimately, V-ties with pressed end-details at their legs could be recommended for the supplementary lateral reinforcement of strengthening columns with jacketing thickness less than the embedment length [= max (75mm, $6d_b$)] of conventional V-ties, where $d_b$ is the diameter of the reinforcing bar used for V-ties.