• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.100-106
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• 2010

Most of the school buildings were built before the seismic code was established. To consider the sunlight and ventilation to the partition walls are built about 1m height beside columns at typical school buildings. For the reason, columns which is consisted school building occur brittle failure shape by the reduced effective depth. In this study, experimental test for retrofitting effect by Aramid Fiber Reinforced Polymers(AFRP) strips on masonry infilled reinforced concrete(RC) frames is performed. The test results were to ensured enough time to evacuate due to the enhancement of ductility and strength of school buildings to withstand earthquakes using AFRP strips.

• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.4
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• pp.189-195
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• 2017

In the seismic design of building structural members, due to the complexity of the placement of PC steels in prestressed concrete members, it is necessary to review and define the definition of member damage in comparison with reinforced concrete members. In this study, the results of past experiments compared with the calculation results by 'section Analysis Method', with the aim of reviewing the precision of calculation results when member damage evaluation is performed using the section analysis method. Furthermore, it is also compared with the calculation results by the 'split Element Method'. In addition, parametric studies were carried out, and the influence of the difference between the amount of PC steels and reinforced bar on the residual strain was examined.

• Advances in concrete construction
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• v.13 no.2
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• pp.133-152
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• 2022

Ecological issues such as natural resource reduction and enormous waste disposals are increasingly leading in developing civilization toward sustainable construction. The two primary environmental issues are the depletion of natural resources and the disposal of trash in open landfills. Waste steel fiber (WSF) was investigated for usage as a cement-based concrete (CBC) constituent in this research. Recycling waste fibers both makes cement composites more long and cost-effective, also aids in pollution reduction. The objective of this study is to analyze the impacts of waste fiber on the fresh and mechanical features of concrete using recycled additives. A comparative research on the durability and mechanical qualities of fiber-reinforced concrete (FRC) constructed with natural aggregates was conducted for this aim. The obstacles to successful WSF recycling methods application in the building industry have been investigated, resulting that CBCs with these fibers make an economic and long lasting choice to deal with waste materials. The workability of fiber enhanced concrete was found to be comparable to that of normal concrete. Fibers have a considerable impact on the splitting tensile strength, flexural and compressive strength of recycled concrete. Fiber may enhance the water permeability. When the WSF content is 0.6 kg/m3, the water absorption is nearly half. Fibers would have no effect on its permeability.

• Earthquakes and Structures
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• v.15 no.3
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• pp.295-306
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• 2018

Reinforced concrete containment (RCC) building has long been considered as the last barrier for keeping the radiation from leaking into the environment. It is important to quantify the performance of these structures and facilities considering extreme conditions. However, the preceding research on evaluating nuclear power plant (NPP) structures, particularly considering mainshock-aftershock seismic sequences, is deficient. Therefore, this manuscript serves to investigate the seismic fragility of a typical RCC building subjected to mainshock-aftershock seismic sequences. The implementation of the fragility assessment has been performed based on the incremental dynamic analysis (IDA) method. A lumped mass RCC model considering the tri-linear skeleton curve and the maximum point-oriented hysteretic rule is employed for IDA analyses. The results indicate that the seismic capacity of the RCC building would be overestimated without taking into account the mainshock-aftershock effects. It is also found that the seismic capacity of the RCC building decreases with the increase of the relative intensity of aftershock ground motions to mainshock ground motions. In addition, the effects of artificial mainshock-aftershock ground motions generated from the repeated and randomized approaches and the polarity of the aftershock with respect to the mainshock on the evaluation of the RCC are also researched, respectively.

• Journal of the Korea Institute of Building Construction
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• v.13 no.5
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• pp.506-512
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• 2013

Since the amendment of the law on the private sector investment in social infrastructure in January of 2005, the government has been actively promoting Build-Transfer-Lease (BTL) projects. Notably, most new educational facilities have been built as BTL projects. For these facilities, the unit cost per unit area has been applied to predict construction costs. However, since construction costs are mostly managed after the detailed design phase, the costs can be estimated incorrectly. For this reason, cost management is needed in the planning phase, with a sound approximate estimate to prevent the wasteful use of funds. To address this shortcoming, this study aims to develop a quantity prediction model for education facilities using regression analysis in the planning phase. The developed model is focused on the required quantities of reinforced concrete and bricks. In order to achieve the objective, the data of 44 educational facility projects collected from Gyeonggi-do was used in the regression model. This study can be utilized by major stakeholders to accurately predict construction costs by estimating the appropriate quantities of reinforced concrete and bricks in the planning design phase.

• International Journal of Concrete Structures and Materials
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• v.18 no.2E
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• pp.133-142
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• 2006

An experimental study was conducted to investigate the effectiveness of transverse steel in reinforced concrete tied columns subjected to monotonically increasing axial compression. Eighteen large-scale columns($260{\times}260{\times}1,200mm$) were tested. Effects of such main variables as concrete compressive strength, configurations of transverse steel, transverse reinforcement ratio, spacing of transverse steel, and spalling of concrete cover were investigated. High-strength concrete columns under concentric axial loads show extremely brittle behavior unless the columns are confined with transverse steel that can provide sufficiently high lateral confinement pressure. A consistent decrease in the deformability of the column test specimens was observed with increasing concrete strength. Test results of this study were compared with existing confinement models of modified Kent-Park, Sheikh-Uzumeri, Mander, and Saatcioglu-Razvi. The comparison indicates many existing models to predict the behavior of confined concrete overestimate or underestimate the ductility of confined concrete.

• Journal of the Korea Institute of Building Construction
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• v.17 no.5
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• pp.403-409
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• 2017

In this study, mix proportioning of porous concrete with compressive strength and porosity exceeding 3MPa and 30%, respectively, was examined and then load capacity and flexural toughness of the porous concrete block were evaluated according to the different arrangements of the GFRP bars. To achieve the designed requirements of porous concrete, it can be recommended that water-to-cement ratio and cement-to-coarse aggregate ratio are 25% and 20%, respectively, under the aggregate particle distribution of 15~20mm. The failure mode of porous concrete blocks reinforced with GFRP bars was governed by shear cracks. As a result, very few flexural resistance of the GFRP was expected. However, the enhanced shear strength of porous concrete due to the dowel action of the GFRP bars increased the load capacity and toughness of the blocks. The porous concrete blocks reinforced with one GFRP bar at each compressive and tensile regions had 2.1 times higher load capacity than the companion non-reinforced block and exhibited a high ductile behavior with the ultimate toughness index ($I_{30}$) of 43.4.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.385-392
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• 2011

In this study, experimental research was carried out to evaluate and improve the seismic performance of reinforced concrete beam-column joint regions using strengthening materials (steel plate, carbon fiber sheet, and embedded carbon fiber rod) in existing reinforced concrete buildings. Six specimens of retrofitted beam-column joints are constructed using various retrofitting materials and tested for their retrofit performances. Specimens designed by retrofitting the beam-column joint regions (LBCJ series) of existing reinforced concrete building showed a stable mode of failure and an increase in load-carrying capacity due to the effect of crack control at the time of initial loading and confinement from retrofitting materials during testing. Specimens of LBCJ series, designed by the retrofitting of FRP in reinforecd beam-column joint regions increased its maximum load carrying capacity by 26~50% and its energy dissipation capacity by 13.0~14.4% when compared to standard specimen of LBCJC with a displacement ductility of 4.

• Journal of Industrial Technology
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• v.38 no.1
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• pp.21-27
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• 2018

In January 2018, the Ministry of Education published "Seismic design criteria for school buildings" and "Manual for seismic performance evaluation and retrofit of school buildings" to evaluate seismic performances through linear analysis. This paper evaluates the seismic performance of an old school building through the linear analysis. The target building was constructed in the late 1970s, and the seismic-force-resisting system was assumed to be a reinforced concrete moment frame with an un-reinforced masonry wall. As a result of the evaluation, the target building does not satisfy the 'life safety' level of 1.2 times the design spectrum. The average strength ratio of moment frames, an indicator of the level of seismic performance tends to be controlled by beams. However, through the Pohang earthquake, it was known that the short column effect caused by the partially infilled masonry wall caused shear failure of the columns in school buildings. Therefore, it is necessary to improve the linear analysis so that the column controls the average strength ratio of moment frames.

• Journal of the Korea Institute of Building Construction
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• v.10 no.6
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• pp.7-17
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• 2010

Modern construction technology has been highly systemized, which has simplified the construction methods applied to construction sites. However, on reinforced concrete construction sites, there have recently been many new disasters, and these have been bigger than before due to the heavy dependency on manpower. This study investigates the cause and cases of disasters during reinforced concrete construction. In addition, the study surveyed the psychological condition of construction site personnel in relation to the safety awareness and the causes of disasters, while deriving the basic components related to disasters on construction sites in order to analyze the relationship between each component to suggest an efficient safety management measures checklist. Construction site personnel should utilize the results drawn from this study as a disaster prevention tool to use in a safety education class, and not consider this simply as statistical data, but as a checklist to ensure full awareness of the appropriate priorities for safety categories to utilize in the reinforced concrete construction in order to execute reasonable safety management.