• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.2
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• pp.351-365
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• 2002

The box system that is composed only of reinforced concrete walls and slabs we adopted on many high-rise apartment buildings recently constructed in Korea. And the framed structure with shear wall core that can effectively resist horizontal forces is frequently adopted for the structural system for high-rise building structures. In these structures, a shear wall may have one or more openings for functional reasons. It is necessary to use subdivided finite elements for accurate analysis of the shear wall with openings. But it would take significant amount of computational time and memory if the entire building structure is subdivided into a finer mesh. An efficient analysis method that can be used regardless of the number, size and location of openings is proposed in this study. The analysis method uses super element, substructure, matrix condensation technique and fictitious beam technique. Three-dimensional analyses of the box system and the framed structure with shear wall core having various types of openings were performed to verify the efficiency of the proposed method. It was confirmed that the proposed method have outstanding accuracy with drastically reduced time and computer memory from the analyses of example structures.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.2
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• pp.237-249
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• 2002

The wall system that is composed only of reinforced concrete walls and slabs is adopted on many high-rise apartment buildings recently constructed. In the apartment buildings, a shear wall may have one or mote openings for functional reasons. Many researches on the analysis of shear wall with openings were performed. But, some restrictions prevent those research results being applied to practical analysis and design procedure. It is necessary to use subdivided finite elements lot accurate analysis of the wall system with openings. But it would cost tremendous amount of analysis time and computer memory if the entire building structure is subdivided into a finer mesh. An efficient analysis method which can be used regardless of the number, size and location of openings is proposed in this study. The analysis method uses super element, matrix condensation technique and fictitious beam technique. Analyses of example structures having various types of openings were performed to verify the efficiency of proposed method. It was confirmed that the proposed method have outstanding accuracy with drastically reduced time and computer memory from the analyses of example structures.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.387-399
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• 2003

The box system that consists only of reinforced concrete walls and slabs we adopted in many high-rise apartment buildings recently constructed in Korea. Recently, many of the box system buildings with pilotis has been constructed to meet the architectural design requirements. This structure has abrupt change in the structural properties between the upper and lower parts divided by transfer girders. For an accurate analysis of a structure with pilotis, it is necessary to have the buildings modeled into a finer mesh. But it would cost tremendous amount of computational time and memory. In this study, an efficient method is proposed for an efficient analysis of buildings those have pilotis with drastically reduced time and memory. In the proposed analysis method, transfer gilders are modeled using super elements developed by the matrix condensation technique and fictitious beams are introduced to enforce the compatibility conditions at the boundary of each element. The analyses of example structures demonstrated that the proposed method used for the analysis of a structure with pilotis will provide analysis results with accuracy for the design of box system buildings.

• Cross-Cultural Studies
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• v.21
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• pp.53-86
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• 2010

This paper is focused on splitting of the first Soviet theatre, MKhAT and collapse of Soviet theatre. A close attention has been paid to Art Theatres's circumstances leading to splitting, critical conscience about division between ideal and real theatres and other concrete situation before the verge of collapse. Administrative reform of the Soviet theatre at the period of Perestroika and Glasnost', its results and conflicts, occurred in the process of transition into market system. These are considered under the premise of that the problems of MKhAT were not so different to the other soviet theatres at that time. As it is known that Moscow Art Theatre is a symbol of Russian theatre. And the status of MKhAT as a symbol of Russian theatre had formulated not only the well-known Stanislavsky' system and his legendary performance The Seagull, Three Sisters etc. It was made by party's effort to make MKhAT as the first Soviet theatre and by directors, artists and critics, they had believed and tried to protect idea of MKhAT as the 'battlements' of Soviet theatrical art. One of them is O. Yefremov, a former leader and artistic director from 1970 to 2000. Actually from the periods of Sovremennik Yefremov knew that does not exist the ideal MKhAT, excepting myths, legends and administrative attitudes. Nonetheless he chose the duty of MKhAT's artistic director to construct ideal MKhAT, theatre as the best moral institution, theatre as union based on common belief. It is same motive that he had led split of MKhAT. But split of theatre did not bring the expected results. After spliting MKhAT has become almost collapsed under collapse of USSR and subsequent turmoil at 1990's. And as soviet theatre disappeared into history, Russian theatre became lost its special significance, the super-theatre's idea.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.2 s.72
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• pp.139-150
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• 2006

ILM(incremental launching method) bridge is one of the prestressed concrete bridge construction methods widely adopted owing to its effectiveness for the quality control. The sections of the launched superstructure pass every position of the bridge spans. This launching process causes the bridge sections to be experienced in the quite different stress states with the stress state occurred after construction completely. Due to the self weight of sections, particularly, the superstructure sections(deck) experience maximum positive and negative moment as well as maximum shear force during launching process. To minimize the temporarily caused sectional forces, launching nose is generally used in the construction method. Therefore, the magnitude of this sectional forces should be checked for the safety of super structure in construction and it is dependent on the structural characteristics of launching nose. In this study, the simplified formulas to analyze the sectional force occurred by the nose-deck interaction in ILM construction are developed. The considering parameters are the span length ratio, stiffness ratio and weight ratio between the launching nose and the super structure. In particular, the developed formulas can consider the tapered sectional shape of launching nose and the diaphragm wall in the superstructure. Additionally, the sensitivity analysis is performed to analyze the effects of nose-deck interaction according to the design parameters.

• Journal of the Korea Institute of Building Construction
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• v.13 no.4
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• pp.407-415
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• 2013

The purpose of this research is to verify the performance of hardening accelerator in cement paste through mechanical performance evaluation and micro structure analysis on hardening accelerator for development of super high early strength concrete. The research results showed that hardening accelerator produced $Ca(OH)_2$ when hydrated with cement, enhancing the degree of saturation of Ca ion by using differential thermal analysis. Moreover, porosity was reduced rapidly as capillary pores were filled by hydration products of $C_3S$. According to the experiment using hydration measurement testing, when 1% and 3% of accelerator were mixed, hydration rate increased toward the second peak point compared to high early strength cement, before the first peak point disappeared. It turned out that adding accelerator accelerated the hydration rate of cement, especially $C_3S$. The shape of C-S-H is shown depending on the amounts of accelerator added and the production and age of $Ca(OH)_2$ by using SEM to observes hydration products. Therefore, it's evident that hardening accelerator used in this research increases amounts of $Ca(OH)_2$ and accelerates $C_3S$, it is effective for the strength development on early age.

• Journal of the Korea Institute of Building Construction
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• v.15 no.1
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• pp.25-33
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• 2015

In this study, initial crack index was evaluated by FEM analysis to find the crack propagation from hydration heat in precast concrete. As results, as the usage of hardening accelerator increased, initial compressive strength increased and setting time was shortened. Additionally, as amounts of hardening accelerators increased, the central temperature of concrete increased and the time to reach the highest temperature was shortened. It was demonstrated that the hardening accelerators accelerated the hydration reaction of cement, and caused the increase of hydration heat within the short period of time. Furthermore, the crack index for evaluating the heat level was performed by FEM. As results, there was no problem about the cracks, despite of the growth of initial high hydration heat. This is because of the increased tensile strength that is large enough to sustain the thermally induced-stress.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.1
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• pp.111-116
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• 2022

Recently, building structures tend to be super high-rise and large-scale with the development of concrete technology. When high-rise building is constructed of reinforced concrete structure, it has a disadvantage that its own weight increases. Light weight aggregate(LWA) was developed to compensate for these shortcomings. Manufacturing concrete using these light weight aggregates has the advantage of reducing the self weight of the reinforced concrete structure, but has a disadvantage in that the strength of the concrete is reduced. In this study, an experimental study was conducted to investigate the strength characteristics of hardened cement according to the presence or absence of surface coating of lightweight aggregates. As a result, in terms of compressive strength, the surface-coated lightweight aggregate exhibited higher strength than the uncoated lightweight aggregate. Also, it was considered that this is because the interfacial voids of the surface coated lightweight aggregate mixed cement hardened body were filled with blast furnace slag fine powder particles.

• Journal of the Korea Institute of Building Construction
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• v.23 no.6
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• pp.703-714
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• 2023

This research conducts a series of tests to investigate the setting retarding properties and strength development in cement pastes incorporating various types and dosages of sugar-based super retarding agents. Six such agents, including Sucrose, Sugar powder, Saccharin, Aspartame, Stevioside, and Mogroside, commercially available, were selected for evaluation. The study also examines the micro-structural properties of these cement pastes. The test mixtures were prepared using a 27.5% water-to-cement ratio and ordinary Portland cement. Micro-structural analyses were conducted using Scanning Electron Microscopy(SEM), X-Ray Diffraction(XRD), and Energy Dispersive Spectroscopy(EDS). The findings reveal that the incorporation of sucrose, sugar powder, and stevioside significantly retards the setting time. Particularly, adding 0.1% sucrose extended the setting time by approximately two-fold compared to the control(Plain) mixture. Most mixtures, barring those with sugar powder and stevioside, exhibited compressive strength comparable to the Plain mixture. Notably, with 0.2% sucrose, strength measurements were not feasible at 1 day, but at 3 days, the strength gains aligned with the Plain mixture. XRD, SEM, and EDS analyses confirmed the hydration delay(set retarding) of C3S due to sucrose, with further quantitative corroboration provided by EDS. SEM was used to verify the presence or absence of hydration products. The study concludes that sucrose, as a sugar-based retarder, offers effective set retarding capabilities and compressive strength development in concrete.

• Korean Journal of Construction Engineering and Management
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• v.5 no.6 s.22
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• pp.235-244
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• 2004

The effective management of major construction resources is the key to the success in high-rise residential building construction projects. It is even more important and challenging as well especially in CBD(central business district) area under tight project duration since little leeway in interface between construction trades, severe constraints in staging n and heavy demands for lifting among construction resources. In order to meet high demands among major construction resources, highly effective construction resource management information system is required This research develops and provides a system which selects and disseminates these information from each phase of procurement transportation, lift-up and storage for major construction resources This research applies the Kanban system, well recognized material information system technique in automobile manufacturing industry, in concrete work processes. It develops concrete procurement information system utilizing VSM(Value Stream Mapping) and also applies the model in actual super-high rise residential building construction project in order to analyze the benefit of the research model.