• Structural Engineering and Mechanics
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• v.64 no.2
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• pp.183-194
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• 2017

This paper presents the experimental investigation into a new type of steel-concrete hybrid outrigger system developed for the high-rise building structure. The steel truss is embedded into the reinforced concrete outrigger wall, and both the steel truss and concrete outrigger wall work compositely to enhance the overall structural performance of the tower structures under extreme loads. Meanwhile, metal dampers of low-yield steel material were also adopted as a 'fuse' device between the hybrid outrigger and the column. The damper is engineered to be 'scarified' and yielded first under moderate to severe earthquakes in order to protect the structural integrity of important structural components of the hybrid outrigger system. As such, not brittle failure is likely to happen due to the severe cracking in the concrete outrigger wall. A comprehensive experimental research program was conducted into the structural performance of this new type of hybrid outrigger system. Studies on both the key component and overall system tests were conducted, which reveal the detailed structural response under various levels of applied static and cyclic loads. It was demonstrated that both the steel bracing and concrete outrigger wall are able to work compositely with the low-yield steel damper and exhibits both good load carrying capacities and energy dispersing performance through the test program. It has the potential to be applied and enhance the overall structural performance of the high-rise structures over 300 m under extreme levels of loads.

• Journal of the Korea Institute of Building Construction
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• v.20 no.2
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• pp.137-145
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• 2020

The recent bridge construction projects demand thorough and systematic safety and risk management, due to the increase of risk factors following the introduction of new and complex construction methods and technologies. Among many types of damages that can occur in bridge construction projects, the damages to third parties who are not directly related to the existing property of the contractor construction project can also bring about critical loss in the project in order to compensate the damages. Therefore, risks that could be caused by the loss occurred to indemnify the third party damages should be clearly analyzed, although there are not subsequent amount of studies focusing on the issue. Based on the past record of insurance payment from domestic insurance companies for bridge construction projects, this study aimed to analyze the risk factors of bridge construction for loss caused to compensate the third-party damages happened in actual bridge construction projects and to develop a quantified and numerical predictive loss model. In order to develop the model, the loss ratio was selected as the dependent variable; and among many analyzed independent variables, the superstructure, foundation, flood, and ranking of contractors were the four significant risk factor variables that affect the loss ratio. The results produced can be used as an essential guidance for balanced risk assessment, supplementing the existing analysis on material losses in bridge construction projects by taking into account the third-party damage and losses.

• Advances in concrete construction
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• v.14 no.3
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• pp.169-183
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• 2022

In this article, vibrational behavior and wave propagation characteristics in (FG) functionally graded plates resting on Kerr foundation with three parameters is studied using a 2D dimensional (HSDT) higher shear deformation theory. The new 2D higher shear deformation theory has only four variables in field's displacement, which means has few numbers of unknowns compared with others theories. The shape function used in this theory satisfies the nullity conditions of the shear stresses on the two surfaces of the FG plate without using shear correction factors. The FG plates are considered to rest on the Kerr layer, which is interconnected with a Pasternak-Kerr shear layer. The FG plate is materially inhomogeneous. The material properties are supposed to vary smoothly according to the thickness of the plate by a Voigt's power mixing law of the volume fraction. The equations of motion due to the dynamics of the plate resting on a three-parameter foundation are derived using the principle of minimization of energies; which are then solved analytically by the Navier technique to find the vibratory characteristics of a simply supported plate, and the wave propagation results are derived by using the dispersion relations. Perceivable numerical results are fulfilled to evaluate the vibratory and the wave propagation characteristics in functionally graded plates and some parameters such wave number, thickness ratio, power index and foundation parameters are discussed in detail.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.6
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• pp.451-461
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• 2010

Utilization of the fiber reinforced polymer (FRP) material has been enlarged as a substitution material to the general construction materials having certain long-term problems such as corrosion, etc. However, it could be difficult to apply the FRP material, which has a linear shape generally, to an arch-shaped tunnel structure. Therefore, an attempt has been made in this study to develop a device to form a designed cross section of FRP material by pulling out with a curvature. A sample of the circled FRP product was successfully produced and then the sample has been tested to identify its physical characteristics. Then, intensive feasibility studies on the circled FRP panel to be used for a tunnel lining structure have been carried out by numerical analyses. As a result, it appears that the new circled FRP-concrete composite panel has a high capability to be used for a tunnel lining material without any structural problem.

• Journal of the Korea Institute of Building Construction
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• v.10 no.1
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• pp.193-198
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• 2010

This study aimed at presenting the improvement plan for estimation of the repair and replacement cycle to analyze these current problems by considering the repair and replacement cycle theoretically and examining estimation status of home and abroad, and then drawing implication and problem based on brainstorming and expert opinion. The findings of a study is as follows. First, the problem is, for the domestic, that there is no clear standard of division to the cycle of repair and replacement and the repair and replacement cycle considering capability to deal with the change by construction method, development of the function of material and the number of years of progress is not being applied. That is, an estimation of economical repair and replacement cycle which considers the case that a large scale repair with the level of remodeling is done between 25 years and 35 years is necessary. For estimating the repair and replacement cycle, foreign country is providing this according to the use or the level of function of a building, but it is not the case for the domestic. A characteristic of each building should be reflected and the standard of estimation of the repair and replacement cycle to new construction material or method should be prepared to improve this. In addition, the method of classification of the subject item for the repair and replacement is necessary to be reorganized to be able to apply the standard of initial construction item of a building. Also, it is considered that a service standard which can reset the repair and replacement cycle based on status of a building with escape from the existing definite setup of the repair and replacement cycle through the management of background data of the repair and replacement is going to be necessary.

• Korean Journal of Construction Engineering and Management
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• v.10 no.6
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• pp.146-153
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• 2009

The year 2008 was a hard year for Korea's construction companies. The real estate downturn resulted in halting new construction and stopping existing work, and inflation of global oil prices caused price hikes in rebar and concrete materials. As a solution to reducing the budget, the newly appointed government announced plans to increase low cost bid contracts from 10 billion to 30 billion won. When such economical and political factors negatively impact the construction market, projects based on low cost contracts are the hardest hit. Many problems already inherent in low cost bid contracts become accentuated. Consequently, this provides an opportune time to actually study and analyze the issues in these projects. This paper introduces the findings made from investigating four projects struggling to make ends meet in the year 2008. Results show that flow of cash (i.e., liquidity), or lack thereof, was the root cause which in turn was hampered by failed mechanisms for design changes, material inflation. Attributing cash flow risk to the bottom of the production structure (i.e., small business subcontractors) was also a problem within the industry. Contractors need a better way to prepare against material price fluctuations, and owners need to assist in expediting payment during times of extreme downturn.

• Korean Journal of Construction Engineering and Management
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• v.14 no.4
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• pp.84-96
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• 2013

Recently, architectural design has been changing from formal design to freeform design due to the digitalization of construction industry. Especially, the formal design has been accepted as a design trend recently and applied many times as a design concept in the architectural design competitions such as turn-key. However, various deflects such as water leak and cracks have been occurred because the traditional construction methods had been applied without any revision or adaptation of the formal construction method for the freeform building construction. Design and construction of freeform building has been developed as an new method in order to solve the problems and minimize the construction duration and cost for the freeform building. Therefore this research deduced the positive implications for developing freefrom envelope by analyzing the domestic and abroad cases and proposed the considerations during design and construction of the freeform envelope as follows. First, the freeform design should consider the constructability for the freeform envelope. Second, manufacturing technology for the two-way curvature of the unit panel should be developed. Third, exposed concrete form method should be developed for the freeform envelope of concrete. Forth, material characteristics, construction method and facility management should be considered in order to manage precipitation and keep water-proof according to the classification of the freeform envelope area.

• Journal of Korean Society of Steel Construction
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• v.24 no.5
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• pp.583-593
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• 2012

The domestic research of the steel plate concrete structures have been focused on the nuclear structures requiring much strong resistance. There are many advantages in the steel plate-concrete structures such as the possibility of prefabricated production and modular construction. This research tried to establish some basic design information of SC structures toward mid to low-rise general buildings with low strength. To reduce the strength mentioned, the some of the cement in weight was replaced by the soils which are traditional and environmental oriented material where the new system can be used to general buildings. This paper studied on the compressive characteristics, effective length factors, buckling loading, steel plate buckling, and stud strength using the compression member subjected to the concentrated compression loadings.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.4
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• pp.314-320
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• 2014

Although the cement industry serves as the cornerstone of the construction industry by supplying one of its fundamental materials, it confronts new environmental challenges due to the problem of the $CO_2$ generated from raw materials and fuel used in the cement manufacturing process. Also, concrete structures can be decomposed and reused as construction materials. Simply in terms of the cyclic processing of $CO_2$, recycling waste concrete to manufacture recycled aggregate or recycling waste concrete powder, which is the material for cement can be considered optimally environment-friendly practices. This study contributes to the aim of manufacturing high value added materials that exploits the chemical properties of the waste concrete powder. From the research results, waste concrete powder is feasible to use to produce low carbon type recycled cement.

• Journal of the Korean Society of Safety
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• v.17 no.1
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• pp.87-93
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• 2002

In this thesis using FTA technique, the author proposes a new method of analysis of some accidents in construction work. Some efficient plans of safe facility investment are made out. For this study, I referred to 'The Death Accident in Construction Works', which have been published by Korea Industrial Safety Corporation from 1993 to 1999 for 6 years. I selected some of apartment constructions which have caused many deaths for the purpose of analysis in the study. I found that the concrete work using ferro-deck takes more deaths than the conventional construction. After finding this, I selected GANG FORM works using ferro-concrete which is the most widely used but causes many accidents. On the basis of the classification, I try to do some quantitative analyses by adding the death frequency and material factors. In order to draw up the most efficient investment plan, it is imperative that FT diagram be made out and that factors. In order to draw up the most efficient investment plan, it is imperative that FT diagram be made out and that minimal Cut Set be needed. It requires a great deal to labor and time to get Minimal Cut Set. The Minimal Cut Set which is formed of these process is the main factor to analyze disaster in the work. It is desirable that we add calculated percentage of accidents to these factors to these factors in value order, that is to say, from the high cost to low cost.