• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.5
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• pp.305-311
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• 2019

In this study, we examined the proper spacing between the expansion joints according to the temperature load of the inter-modal terminal platform infrastructure to implement a new inter-modal automated freight transport system, which we intend to introduce in Korea. To review the proper expansion joint spacing of the terminal platforms, we set the maximum expansion joint spacing according to the regional temperature changes using the equation proposed by the Federal Construction Council (FCC) of the United States. Then, the maximum displacement value, which was calculated through the structural analysis program, and the limit of the horizontal displacement of the building structure were compared. The proper expansion joint spacing was selected as the slab length at which the maximum displacement of the structure, due to temperature changes, was below the horizontal displacement limit. Based on the application of maximum expansion joint spacing for each region calculated through the FCC's suggestion, the maximum displacement that could occur within the limit of the lateral displacement of the structure was determined.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1023-1037
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• 2018

The interest in the use of shield TBM (Tunnel Boring Machine) on the tunnel excavation has been increased rapidly in Korea. The shield TBM tunnel is generally designed as non-drainage tunnel. Consequently, if water leakage through the segment joints happens, big problems on the usage and stability of tunnel can be occurred. In this study, the variation of waterproof capacity of hydrophilic rubber waterstop and gasket, respectively by the construction error and excessive displacement of segment was studied. The test results show that hydrophilic rubber waterstop has favorable on the offset, however unfavorable on the gap. On the other hand, gasket has unfavorable on the offset, however favorable on the gap.

• Journal of the Korea Institute of Building Construction
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• v.23 no.1
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• pp.45-56
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• 2023

This study was conducted to examine the feasibility of preparing a durability evaluation plan in watertightness for sealant applied to a PC structure. To this end, 5 types of sealant that equally satisfy the quality standards of the relevant KS standard were selected and tested. Through this testing, it was found that 3 of the 5 types of sealant showed deterioration in watertightness and durability, such as falling off and cracking from the substrate. For the remaining two types, a visual observation showed no significant changes, but additional analysis, confirmed that there was a large difference in the stress reduction rate of the material. Therefore, based on the above results, the need for a performance review in durability between sealant was confirmed, and based on this, the validity of the durability evaluation plan that can be used in product selection was quantitatively confirmed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4A
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• pp.591-601
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• 2008

The purpose of this study was to investigate the performance of precast concrete segmental bridge columns with shear resistance connecting structure. The system can reduce work at a construction site and makes construction periods shorter. A model of precast concrete segmental bridge columns with shear resistance connecting structure was tested under a constant axial load and a cyclically reversed horizontal load. A computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. An bonded or unbonded tendon element based on the finite element method, that can represent the interaction between tendon and concrete of prestressed concrete member, is used. A joint element is newly modified to predict the inelastic behaviors of segmental joints. The proposed numerical method gives a realistic prediction of performance throughout the loading cycles for several test specimens investigated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.67-74
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• 2006

The use of steel plates has been greatly increased in bridge construction, particularly for long-span bridges. For connections of those steel plates in the field, application of high-tension bold, such as M30, is highly demanded. However, the current steel construction specifications in Korea do not provide information for large-sized bolt connections. In order to evaluate the applicability of the large-sized high-tension bolt, this study experimentally investigates relaxation and slip behavior of M30 bolts with varying bolt size and plate thickness. In addition, internal compressive stress was computed using FEM analysis. The analyzed results were compared with the stress distribution measured from strain gages attached on bolts and bolt holes. From the study presented herein, the M30 high-tension bolts are anticipated to be successfully used with the relaxation less than 10% and the slip coefficient satisfying the specified limit.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.155-156
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• 2023

In the case of steel door frames commonly found in general buildings, there are various assembly methods such as rivets, bolts, and welding, but the welding method is generally used. However, this welding joint method has many problems, such as distortion due to heat and damage due to external shock. In particular, when used as a fire door, problems may occur in the event of a fire due to distortion caused by heat from welding and the weak welded joint area. In the case of rivet or welded joints, when moved after assembly, joint loosening due to external shock may occur. Problems may arise where the bonding strength becomes weak. In addition, with the recent increase in high-rise buildings and larger buildings, when assembly is completed and brought to the site, a place is needed to store it, and in addition, there is a problem in that it has to be transported several times in small quantities to the installation site, which is another problem of time and cost loss. This is coming to the fore. In order to fundamentally solve this problem, we have researched and developed a non-welding door frame that can be assembled on site. We have researched and developed three assembly methods: screw-type, insert-type, and protrusion-type. Non-welded door frames are small in size and easy to package, making them advantageous for domestic and overseas exports.

• Geomechanics and Engineering
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• v.10 no.4
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• pp.547-563
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• 2016

This paper describes a geotechnical field investigation in Giresun hazelnut licenced warehause and spot exchange during twelve months to determine the soil profile and static project applicability. It is also aimed to determine the superstructure loads and evaluate the relevance of foundation filling materials of the main, laboratory, package and admin buildings. The main building has $88.50{\times}63.20(5593.2)m^2$ site area. It has a big raft foundation. Eleven geotechnical reports were prepared between 2 December 2014 and 25 May 2015. Maximum settlements and safe bearing capacities were calculated to decide to be able to proceed to the next step. Also, the detail observations and evaluations were presented from October 2014 to December 2014. It has been seen that the foundation is designed as a single foundation one. But, in the light of observations, it has been evaluated that the foundation project for package building is not adequate, and after these excavations it must be revised as a raft foundation. The thickness of foundation and structural details should be defined/drawn after analyzing the details by using a special software. Construction joints should be designed between different buildings interfaces to avoid damages and cracks with in different settlements. The environmental drainage must be projected and applied to avoid the probable damage of surface waters on foundations.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1994.10a
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• pp.160-166
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• 1994

In general, the problems of strengthening and repairing of deteriorated or damaged reinforced concrete members are usually worked out in situ by externally bounding steel plates using epoxy resins, which has been recognized to be one of effective and convenient methods. But the disadvantages of strengthening/repairing concrete members with externally bonded steel plates include ; (a) deterioration of the bond at the steel-concrete interface caused by the corrosion of steel ; (b) difficulty in manipulating the plate at the construction site ; (c) improper formation of joints, due to the limited delivery lengths of the steel plates ; and etc. Therefore these difficulties eventually have led to the concept of replacing the steel plates by fiber-reinforced composite sheets which are characterized by their light weight, extremely high stiffness, excellent fatigue properties, and outstanding corrosion resistance. In the paper, for the reliability assessment of reinforced concrete beams externally strengthened by carbon fiber plastic(CFRP) laminates, an attempt is made to suggest a limit state model based on the strain compatibility method and the concept of fracture mechanics. And the reliability of the proposed models is evaluated by using the AFOSM method. The load carrying capacity of the deteriorated and/or damaged RC beams is considerably increased. Thus, it may be stated that the post-strengthening of concrete beams with externally bonded CFRP materials may be one of very effective way of increasing the load carrying capacity and stiffeness characteristics of existing structures.

• Advances in concrete construction
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• v.9 no.1
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• pp.1-7
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• 2020

Retrofitting is an alteration of existing member or component of the structure. In civil engineering point of view, it is called strengthening of the old structure. Deterioration of structures may be due to aging, corrosion, failure of joints, earthquake forces, increase in service loads, etc. Such structures need urgent repair, retrofitting and strengthening to avoid collapse, cracking and loss in strength or deflection. Advanced techniques are required to be developed for the repair of structural components to replace conventional techniques. This paper focuses exclusively on torsional behaviour of Reinforced Concrete (RC) beams and retrofitted RC beams wrapped with aramid fiber. Beams were retrofitted with aramid fiber by full wrapping and in the form of 150 mm wide strips at a spacing of 100 mm, 150 mm, 200 mm respectively using epoxy resin and hardener. A total 15 numbers of RC beams of 150 mm×300 mm×1300 mm in size were cast, 3 beams are tested as control specimens, and 12 beams are tested for torsion up to the failure and then retrofitted with aramid fiber. Experimental results are validated with the help of data obtained by finite element analysis using ANSYS. The full wrapping configuration of aramid fiber regains 105% strength after retrofitting. With the increase in spacing of fabric material, torsional strength reduces to 82% with about 45% saving in material.

• Advances in concrete construction
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• v.9 no.1
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• pp.43-54
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• 2020

This paper presents an innovative stress-function variational approach in formulating the interfacial shear and normal stresses in an externally bonded concrete joint using carbon fiber-reinforced plastic (CFRP) plies. The joint is subjected to surface traction loadings applied at both ends of the concrete substrate layer. By introducing two interfacial shear and normal stress functions on the CFRP-concrete interface, based on Euler-Bernoulli beam idea and static stress equations of equilibrium, the entire stress fields of the joint were determined. The complementary strain energy was minimized in order to solve the governing equation of the joint. This yields an ordinary differential equation from which the interfacial normal and shear stresses were proposed explicitly, satisfying all the multiple traction boundary conditions. Lamination theory for composite materials was also employed to obtain the interfacial stresses. The proposed approach was validated by the analytic models in the literature as well as through a comprehensive computational code generated by the authors. Furthermore, a numerical verification was carried out via the finite element software ABAQUS. In the end, a scaling analysis was conducted to analyze the interfacial stress field dependence of the joint upon effective issues using the devised code.