• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.1
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• pp.1-8
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• 2016

In this paper, we perform structural analysis for a base frame which is used to support a motor for large centrifugal compressor drives and a safety assessment according to the concrete placement. First, the structural analysis about four loading conditions for the motor base frame was conducted and the structural safety was evaluated through both the maximum distortion energy theory and Mohr-Coulomb theory. It was possible to perform a more reasonable safety evaluation against local stresses occurring at the discontinuous portion of the fragile structural members by applying the safety assessment through ASME VIII Div. 2. In addition, the motor base frames with and without the internal concrete placement were quantitatively compared by the structural analysis and safety evaluation using ASME code and it was found to improve the structural integrity due to the concrete placement.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.139-152
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• 1999

These days we broadly apply drilled shafts for deep foundations to build infrastructures. The defects of the deep foundations cause the decrease of their support load capacity and the increase of settlement, and the subsequent damage of the super-structures. In consequence, non-destructive testings techniques of concrete piles are important for their integrity evaluation. To improve understanding and reliable application of the impact echo method for the integrity evaluation of the drilled concrete piles, numerical studies of the impact response of concrete piles by using axi-symmetric three-dimensional finite element method are peformed for (a) sound piles: (b) piles containing necks, voids and layers of low-quality concrete: and (c) piles in soil and/or above rock. The results of these studies show that the finite element method is effective for evaluating the impact response of drilled concrete piles.

• Magazine of the Korea Concrete Institute
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• v.6 no.5
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• pp.140-148
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• 1994

RCI 318-8!4 recommends that when the specified cornpresslve strength of concrete In a column is greater than 1.4 times thdt spec~f~ed for a floor svsttm. top surface of the colunm concrete shall extend 2ft(600mm) into the slab from the face of colurnn to avoid unexpected brittle failure. Six test specimens were cast arid tested on 2/3 scale frame specmiens havlng different extension distances and compressive strength of concrete as the major variables. The paper discusses the performance of the frames in terms of ductility and also presents the assessment of the ACI 318-89 provisions.The test results showed that the ductility index were incrrased with increasing of compressive strength of concrete and extension distance. And top surface of the column concrete should extend 2h(h overall depth of beam) into the beam from the face of the column to avoid unexpected brittle failure in frame.

• Journal of the Korea Concrete Institute
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• v.26 no.4
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• pp.533-543
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• 2014

Currently, composite construction of prestressed Precast Concrete (PC) and Cast-In-Place (CIP) concrete with different concrete strengths are frequently used in the modular construction. However, current design codes do not clearly define shear design methods for such composite beams. In this present study, simply supported prestressed PC-CIP composite beams without vertical shear reinforcement or only with horizontal shear reinforcement were tested to evaluate the effect of prestressing on the shear strength and the shear design method for such composite members. The test variables were the area ratio of PC and CIP concretes, prestressing force, shear span-to-depth ratio, and shear reinforcement ratio. The results showed that the shear strength was increased by the increase of prestressing force and prestressed PC area, and the decrease of shear span-to-depth ratio.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.315-319
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• 2007

지하에 설 치된 맨홀의 구조물이 노후되거나, 내부에 수 용된 시설물로 작업 공간이 협소하여 맨홀 구조물을 대개체 할 펼요가 있을 경우, 지금까지는 대부분 현장 콘크리트 타설에 의한 방법을 사용하였다. 이러한 방법은 거푸집 시공, 콘크리트 타설, 콘크리트 양생, 거푸집 철거 등의 공정이 소요되어 공사 기간이 장기화 되고, 도심지에 위치한 맨홀인 경우에는 차량과 보행자의 통행 불편을 초래하기도 하였다. 또한, 통상적으로 사용되고 있는 프리캐스트 맨홀에 비해 시공 품질이 낮아 향후 맨홀의 운용 및 유지관리에 많은 어려움을 겪는 원인이 되기도 하였다. 본 논문에서는 이러한 문제점들을 해결하기 위해, 폴리머 콘크리트를 이용하여 하부, 벽체, 상부로 구성된 다수의 세그먼트를 생산한 후, 현장에서 이들 세그먼트를 조립하여 맨홀을 설치하는 방법을 연구하였다. 가변형 거푸집을 이용한 세그먼트 제작과 조립식 블록에 의한 관구를 사용하여 현장 적용성을 높임은 물론, 프리캐스트로 생산되는 폴리머 콘크리트 맨홀 수준의 시공 품질을 확보할 수 있도록 하였다.

• 레미콘
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• no.6 s.28
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• pp.118-121
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• 1991

• Journal of the Korea Concrete Institute
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• v.13 no.1
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• pp.69-76
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• 2001

Foamed concrete for cast-in-site, which shows excellent lightweight, thermal insulation, noise insulation, constructability and cost efficiency, has been applied as thermal insulation or filling material for On-dol. However, the technology is too insufficient to obtain the high level of quality, and serious problems often occur in quality control at sites. It, thus, is necessary to establish the proper and reasonable quality control method for ensuring the required quality, based on the investigation on the physical properties and their reciprocal relation. This study aims to settle the quality control method in case of applying FA foamed concrete replacing 40% by weight with fly-ash as the filling material for On-dol. The results of the study include the correlation among flow, as-placed density and foam ratio of fresh foamed concrete, the correlation between physical properties before hardening and after 28-day, provision of an equation to estimate 28-day compressive strength early with 7-day compressive strength, and suggestion of quality criteria for the revision of KS on foamed concrete for cast-in-site.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.989-992
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• 2008

In this paper, we are presenting a case that integrates ultra high strength concrete(150MPa) with surface-exposed concrete. Ahead of the field application, we carried out laboratory experiment and B/P Test for a basic property of concrete(slump flow, air content, 50cm flow time, elapse time change and compression strength) and productivity. The next, we conducted Mock-up Test using simulation specimen to evaluate infilling, surface-finishing and hydration heat of concrete. We had satisfactory results for a basic property and hydration heat of concrete. However at the time of field application, it was occurred rupture of formwork because of high lateral pressure of concrete, and then formwork was reinforced and case-in-place time was adjusted. And regardless of low and high frequency vibration, it occurred to surface-pockmark. In case that applies ultra high strength concrete to surface-exposed concrete, we estimate that it is important of systematic management and improvement of construction.

• Magazine of the Korea Concrete Institute
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• v.3 no.4
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• pp.16-22
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• 1991

• 레미콘
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• no.10 s.69
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• pp.49-63
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• 2001