• Journal of the Korean GEO-environmental Society
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• v.12 no.12
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• pp.55-61
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• 2011

Recently, a concept of the downtown area was progressively extended by improvement of rapid transportation system and development of the most advanced telecommunication industries. And underground has become bigger in addition deeper, Excavation methods which construct a structure were changed according to construction environments. Top Down methods which are continuous with architectural plan differ from existing excavation methods innovatively, pre-founded column is an important factor for construction methods, duration, expenses. Therefore, this study considers application by investigative methods according to comparison, analysis on loading test result of on site inspection and estimated results of bearing capacity for structure pre-founded column. As a result, almost designing eclipse appeared prior value which didn't arrive result of load test. Also, evaluate permanent load for the compressive stress acting on head of cast-in-place after basic structure was installed. Then, applying stress generally is reduced by confining effect with foundation.

• Structural Engineering and Mechanics
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• v.71 no.4
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• pp.433-444
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• 2019

Shear studs are often used to connect steel girders and concrete deck to form a composite bridge system. The application of precast concrete deck to steel-concrete composite bridges can improve the strength of decks and reduce the shrinkage and creep effect on the long-term behavior of structures. How to ensure the connection between steel girders and concrete deck directly influences the composite behavior between steel girder and precast concrete deck as well as the behavior of the structure system. Compared with traditional multi-I girder systems, a twin-I girder composite bridge system is more simplified but may lead to additional requirements on the shear studs connecting steel girders and decks due to the larger girder spacing. Up to date, only very limited quantity of researches has been conducted regarding the behavior of shear studs on twin-I girder bridge systems. One convenient way for steel composite bridge system is to cast concrete deck in place with shear studs uniformly-distributed along the span direction. For steel composite bridge system using precast concrete deck, voids are included in the precast concrete deck segments, and they are casted with cast-in-place concrete after the concrete segments are erected. In this paper, several sets of push-out tests are conducted, which are used to investigate the heavier of shear studs within the voids in the precast concrete deck. The test data are analyzed and compared with those from finite element models. A simplified shear stud model is proposed using a beam element instead of solid elements. It is used in the finite element model analyses of the twin-I girder composite bridge system to relieve the computational efforts of the shear studs. Additionally, a parametric study is developed to find the effects of void size, void spacing, and shear stud diameter and spacing. Finally, the recommendations are given for the design of precast deck using void for twin I-girder bridge systems.

• Journal of the Korean Society for Advanced Composite Structures
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• v.7 no.1
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• pp.25-31
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• 2016

Bond stress between cast-in-place ductile fiber reinforced cementitious composites and CFRP plank were experimentally analyzed. As failure shape, the mixture of failure between CFRP plank and epoxy, and failure between concrete and epoxy was shown. In case of RFCON from the suggested simple bond slip relationship, the maximum average bond stress was 5.39MPa, the initial slope was 104.09MPa/mm, and the total slip length was 0.19mm. PPCON showed the maximum average bond stress of 4.31MPa, the initial slope of 126.67MPa/mm, and the total slip length of 0.26mm, while RFCON+ appeared to have 8.71MPa, 137.69MPa/mm, 0.16mm. PPCON+ had 6.19MPa maximum average bond stress, 121.56MPa/mm initial slope, and 0.34mm total slip length. To comprehend the behavior of composite structure of FRP and concrete, local bond slip relation is necessary, and thus a simple relation is suggested to be easily applied on hybrid composite system.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.19 no.3
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• pp.14-22
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• 2023

Steel-pipe civil structures, including steel-pipe energy piles and cast-in-place piles (CIPs), utilize steel pipes as their primary reinforcements. These steel pipes facilitate the circulation of a working fluid through their annular crosssection, enabling heat exchange with the surrounding ground formation. In this study, the cooling performance of a ground source heat pump (GSHP) system that incorporated steel-pipe civil structures was investigated to assess their applicability. First of all, the thermal performance test was conducted with steel-pipe CIPs to evaluate the average heat exchange amount. Subsequently, a GSHP system was designed and implemented within an office container, considering the various types of steel-pipe civil structures. During the performance evaluation tests, parameters such as the coefficient of performance (COP) and entering water temperature (EWT) were closely monitored. The outcomes indicated an average COP of 3.74 for the GSHP system and the EWT remained relatively stable throughout the tests. Consequently, the GSPH system demonstrated its capability to consistently provide a sufficient heat source, even during periods of high cooling thermal demand, by utilzing the steel-pipe civil structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.225-230
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• 2001

Cast-in-place foamed concrete is a high porous material placed as base the layer of mortar screeds in the panel heating system, so the quality of mortar is affected by it. Therefore, this study is aims to investigate how the absorption characteristics of foamed concrete influences on mortar screeds according to the foamed ratio-62%, 67% and 72%- and the surface treatments of foamed concrete-water and acrylic emulsion primer spray, etc. The result of this study shows that water-spray in the surface of foamed concrete has a good effects to reduce mortar cracking.

• 한국지구물리탐사학회:학술대회논문집
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• 1999.08a
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• pp.202-216
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• 1999

The deep foundation is frequently used for the infrastructures. Since the quality control of the cast-in-place concrete foundations such as CIP piles and slurry walls is not so easy as that of the ready made PC(prestressed concrete) piles, it is necessary to get the information on the integrity of the concrete of the foundation. The depth estimation of foundations whose depths are unknown is also very important in repair and reinforcement works or in safety inspection and assessment to the big structures. The cross-hole sonic logging(CSL) system and the single channel reflection seismic measurement system were developed to test the integrity of pile. The former is well applied to CIP structures, while the later to all kinds of piles with less accurate result compared to that of CSL. To estimate the depth of the deep foundations, parallel seismics, borehole RADAR, and borehole magnetics can be used.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.279-286
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• 2002

Recently, there are many attempts to expand a temporary soil nailing system into a permanent wall due to the advantage of soil nailing system, that is efficient and economic use of underground space and decreasing the total construction cost. However, the proper design approach of a permanent soil nailing system has not been proposed by now in Korea. Permanent soil nailing system which utilizes precast concrete walls for the facing of soil nailing system Is already used in many countries. In general, the cast-in-place concrete facings or rigid walls were constructed in bottom-up way after construction of soil nailing walls finished preliminarily In this paper, various laboratory model tests have been carried out to investigate the failure mode, behavior characteristics, and tensile force at nail head in each load level in respects of the variation of stiffness of the facing.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.113-118
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• 2001

The two-girder composite bridge has the girder space of more than 5m, for special case, over than 15m. Therefor, the design and construction of this bridge system require new approaches. To ensure the structural safety, the deck depth should be increased. Therefore, the economically designed deck system is necessary for th two-girder bridge. This study is the first step to develop the deck system for two-girder bridges. In this study, a literatute survey is performed to develop a new deck system for two-girder type of bridges. By considering the characteristics of two-girder bridge system, a cast-in-place PSC deck is proposed for the two-girder bridges. To examine structural behavior and safety of the proposed PSC deck, three real scale partition deck(3m$\times$5m) are tested under the static loading. In the test, the failure mode and behavior of each specimen, and ultimate load carrying capacity of the two-girder-bridge deck are identified.

• Computers and Concrete
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• v.13 no.4
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• pp.501-516
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• 2014

The purpose of this study was to investigate the performance of precast concrete pier cap system. The proposed precast pier cap provides an alternative to current cast-in-place systems, particularly for projects in which a reduced construction time is desired. Five large-scale pier cap specimens were constructed and tested under quasistatic monotonic loading. The computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used for the analysis of reinforced concrete structures. A bonded tendon element is used based on the finite element method, and can represent the interaction between the tendon and concrete of a prestressed concrete member. A joint element is used in order to predict the inelastic behaviors of segmental joints with a shear key. This study documents the testing of the precast concrete pier cap system under monotonic loading and presents conclusions and design recommendations based on the experimental and analytical findings. Additional full-scale experimental research is needed to refine and confirm design details, especially for actual detailing employed in the field.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.281-287
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• 2011

Recently, bridge construction technology has made great progress from development of high performance materials and new bridge types. However, most technology are based on methods of cast-in-place and material cost saving. The method of cast-in-place concrete causes environmental damages and costumer complaints. Especially, under bad weather conditions, the construction can not proceed. To overcome these disadvantages, new construction methods were developed to reduce construction time. These methods are called precast method. Most prefabricated methods have been applied to superstructure constructions of bridges, but very minutely applied to substructure constructions. The most important agendas on precast method are light weight and transportability of the precasted members, because very strict transporting specifications exist for road transportation of the precasted members. For example, the weight and length of coping members may be larger than the available transporting vehicles. Although column is constructed by precast method to save construction time, if coping member is constructed by cast-in-place method, then the column construction time reduction becomes meaningless. Therefore, in this study, a new precast coping member and a connecting system of column-coping member are proposed. The proposed method is verified by analyzing their ultimate performance through analysis and experimental study.