• Steel and Composite Structures
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• v.28 no.6
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• pp.719-734
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• 2018

Prior to the introduction of modern seismic guidelines, it was a common practice to provide straight bar anchorage for beam bottom reinforcement of gravity load designed building. Exterior joints with straight bar anchorages for beam bottom reinforcements are susceptible to sudden anchorage failure under load reversals and hence require systematic seismic upgradation. Hence in the present study, an attempt is made to upgrade exterior beam-column sub-assemblage of a three storied gravity load designed (GLD) building with single steel haunch. Analytical formulations are presented for evaluating the haunch forces in single steel haunch retrofit. Influence of parameters that affect the efficacy and effectiveness of the single haunch retrofit are also discussed. The effectiveness of the single haunch retrofit for enhancing seismic performance of GLD beam-column specimen is evaluated through experimental investigation under reverse cyclic loading. The single steel haunch retrofit had succeeded in preventing the anchorage failure of beam bottom bars of GLD specimen, delaying the joint shear damage and partially directing the damage towards the beam. A remarkable improvement in the load carrying capacity of the upgraded GLD beam-column sub-assemblage is observed. Further, a tremendous improvement in the energy dissipation of about 2.63 times that of GLD specimen is observed in the case of upgraded GLD specimen. The study also underlines the efficacy of single steel haunch retrofit for seismic upgradation of deficient GLD structures.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2003.05a
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• pp.508-513
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• 2003

The objective of this paper is to investigate the lining board's capacity by using the static loading test and fatigue test. Specimens that constitute the H & Channel type lining board are adopted. The test is to inspect the possibility of retrofit and efficiency, which is required to upgrade the structure's capacity and to examine the effects of the improvements of specimen by using structural analysis, stress analysis, static loading test and fatigue test, respectively. The accumulated test results of stress condition and deflection by bending will be used to analyze the relation between the cause of fatigue crack occurrence and the behavior of both structure system and the steel.

• International Journal of Contents
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• v.3 no.3
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• pp.26-31
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• 2007

The purpose of this study is to explore the emergence of Chinese economy and the possibility of economic cooperation between the East Asian countries, which will facilitate the solution to structural problems in the economy and industries of these countries. This study presents that China will remain essential to the East Asian economy and changes are anticipated in its economic growth rate, growth strategy and risks. How to respond to them will be the critical movement that will determine the future course of the East Asian economy. To solve this question, firstly each government of East Asian countries needs to come up with strategies that will leverage China for their industrial upgrade and economic development even when the risks facing China are realized. Second, each government of East Asian countries should make a wise approach towards a free trade agreement between EATR and China.

• Structural Engineering and Mechanics
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• v.40 no.2
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• pp.167-190
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• 2011

In order to upgrade the seismic resistibility of structures and enhance the functionality of an isolator, a new base isolator called the multiple trench friction pendulum system (MTFPS) is proposed in this study. The proposed MTFPS isolator is composed of a trench concave surface and several intermediate sliding plates in two orthogonal directions. Mathematical formulations have been derived to examine the characteristics of the proposed MTFPS isolator possessing numerous intermediate sliding plates. By means of mathematical formulations which have been validated by experimental results of bidirectional ground shaking, it can be inferred that the natural period and damping effect of the MTFPS isolator with several intermediate sliding plates can be altered continually and controllably during earthquakes. Furthermore, results obtained from the component and shaking table tests demonstrate that the proposed isolator provides good protection to structures for prevention of damage from strong earthquakes.

• Journal of Korean Society of Disaster and Security
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• v.12 no.4
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• pp.43-52
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• 2019

To analyze the influence on the stability, resulting from application of upgrade pipe roof structure (UPRS) method to the structure existed under subway Station, physical properties of a ground, elasticity and elasto-plastic theories, including displacement analysis of finite elements, stress analysis of finite elements, displacement caused by steel pipe propulsion and internal excavation, and stress change in a steel pipe, were introduced. Then, the influence on structural stability when applying the UPRS method was compared and reviewed based on the construction management standard of the Ministry Land, Infrastructure and Transport and foreign sources, using numerical analysis with a model which assumes that each microelement divided into a structurally stable point consists of the connection of finite points. As a result of the finite element analysis, 7.21 mm maximum displacement, 1/3,950 angular displacement, 70.28 MPa bending compressive stress of steel pipe structure constructed with UPRS (non-excavation) method and 477.38 MPa maximum shear strength were within their allowable standards (25.00 mm, 1/500, 210.00 MPa and 120.00 MPa, respectively), and therefore, the results showed that the design and construction are stable.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.32-35
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• 2004

In recent years a number of catastrophic tunnel fires, the Euro tunnel, the Mont Blanc tunnel, the Tauem tunnel and the Gotthard tunnel, have occurred and inflicted serious damages to European countries. If a fire occurs in shield tunnels, the reinforced concrete segment linings playing as an important structural member is expected to damage severely and finally can be caused the collapse of tunnel. The purpose of this study is to evaluate the performance of concrete segment lining under heat exposure and to obtain information to assist a new technical approach to fighting fires in tunnels. In order to evaluate the fire-resistance performance of concrete segment by adding Polypropylene fibers, fire tests using the RABT heat-load curve is carried out. The temperature rise of this curve is very rapid up to $1200^{\circ}C$ within 5 minutes, and duration time of the $1200^{\circ}C$ exposure is 55 minutes. From the fire test, it was found that the explosive spalling was rapidly reduced by adding polypropylene fibers and this method is considered as an effective fireproof material to upgrade fire safety in tunnels economically.

• Structural Engineering and Mechanics
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• v.64 no.1
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• pp.135-143
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• 2017

To upgrade shear performance of reinforced concrete (RC) beams, and particularly of the segments under negative moment within continuous T-section beams, a series of original schemes has been proposed using carbon fibre-reinforced polymer (CFRP) U-shaped strips for shear-strengthening. The current work focuses on one of them, in which CFRP U-strips are wound around steel bars against the top of the flange of a T-beam and then spliced on its bottom face in addition to being bonded onto its sides. The test results showed that the proposed scheme successfully provided reliable anchorage for U-strips and prevented premature onset of shear failure due to FRP debonding. The governing shear mode of failure changed from peeling of CFRP to its fracture or crushing of concrete. The strengthened specimens displayed an average increase of about 60% in shear capacity over the unstrengthened control one. The specimen with a relatively high ratio and uniform distribution of CFRP reinforcement had a maximum increase of nearly 75% in strength as well as significantly improved ductility. The formulas by various codes or guidelines exhibited different accuracy in estimating FRP contribution to shear resistance of the segments that are subjected to negative moment and strengthened with well-anchored FRP U-strips within continuous T-beams. Further investigation is necessary to find a suitable approach to predicting load-carrying capacity of continuous beams shear strengthened in this way.

• Structural Engineering and Mechanics
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• v.67 no.1
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• pp.1-8
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• 2018

Shake table tests performed on five 1:3 reduced scale two story RC moment resisting frames having construction defects, have shown severe joint damageability in deficient RC frames, resulting in joint panels' cover spalling and core concrete crushing. Haunch retrofitting technique was adopted herein to upgrade the seismic resistance of the deficient RC frames. Additional four deficient RC frames were built and retrofitted with steel haunch; both axially stiffer and deformable with energy dissipation, fixed to the beam-column connections to reduce shear demand on joint panels. The as-built and retrofitted frames' seismic response parameters are calculated and compared to evaluate the viability of haunch retrofitting technique. The haunch retrofitting technique increased the lateral stiffness and strength of the structure, resulting in the increase of structure's overstrength. The retrofitting increased response modification factor R by 60% to 100%. Further, the input excitation PGA was correlated with the lateral roof displacement to derive structure response curve that have shown significant resistance of retrofitted models against input excitations. The technique can significantly enhance the seismic performance of deficient RC frames, particularly against the frequent and rare earthquake events, hence, promising for seismic risk mitigation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.157-160
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• 2009

The decision of the Form removal time which leads the early assuring strength of the concrete from Apartment construction is the fact which is important from Reducing the period of works and the economical efficiency side. Especially, with Complex building of recent times the same Tall building and Multiple Apartment Site which only follows in upgrade of interior construction of apartment site and shortening the frame construction period becomes very, importantly is the actual condition where the effort which is various for this is attempted. But is caused by with limit and economical efficiency problem of case concrete early strength revelation of most and is not put to practical use is the actual condition. Develops concrete mixture which is a utility from the research which sees hereupon and the effect which is economic leads construction duration shortening under maximizing boil.

• International Journal of Advanced Culture Technology
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• v.10 no.4
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• pp.337-344
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• 2022

The ecological expression of art in modern society takes the harmonious developmental relationship between man and nature as an element and combines it with the various manifestations of painting as an expression of ecological artistic development. The necessary relationship for the harmonious development of nature is accurately articulated, and the ecological changes in people are expressed in integrated materials that inspire human reflection. In the pursuit of material pleasures, mankind is neglectful and indifferent to the environment. The development of composite painting in art and ecology is a process that more reveres the harmony between man and nature as well as satisfying the creative value of the work. After systematic evaluation and research, people have engaged in various structural forms of composite art painting development in the long history of art development, focusing on the integration of environmental and ecological culture.In the process of nature education going through development, the comprehensive practical development of nature education is enhanced and efforts are made to feel new ecological art ideas and new ways of valuing environmental protection. In this paper, an observational study of eco-art will be carried out, starting from the theory of hierarchical division and analyzing the contradictory relationship between man and nature. Recognize nature, understand it and feel it through eco-art painting. The analysis of the contradictory relationship between man and nature is combined with the identification of various types of information that give value to the environmental protection public, and the combination of ecological painting and nature art to achieve an upgrade of the environmental protection idea of the value of painting.