• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.509-512
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• 2008

The lining concrete of water tunnel is a much capability to occur crack due to drying shrinkage and vibrator compaction etc. Because of crack of concrete induce structural problem and decrease durability of concrete, it is need to reduce crack of concrete. In this an Analytical study to analyze the effect of curing of concrete and compaction on the lining concrete. As the results, it was found that control of construction condition into curing of concrete and compaction improve on construction efficiency of the lining concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.709-712
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• 2008

RC super tall buildings are planned and constructed recently in domestic area. Concrete is characterized by time dependant material such as creep and shrinkage. For this properties of concrete, differential shortening is one of the main issues on super tall buildings construction. This study includes material research, which is performing as a pre design stage to solve differential shortening on Lotte Super Tower Jamsil core structure(50, 60, & 70 MPa). The major part of this study is composed with comparison and analysis between experimental data and predicted data on total shrinkage and total compliance which were used on design stage. Four models, ACI209R Model, Ba${\check{z}}$ant-Baweja B3 Model, CEB MC99 Model, & GL2000 Model, were employed to predict them. It also tries to seek a proper model for high strength and high performance concrete in the case of no concrete test.

• Journal of the Korea Concrete Institute
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• v.26 no.5
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• pp.635-642
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• 2014

The weight of concrete could be reduced by using hollow core slabs instead of heavy solid slabs, leading to cost reduction. The long span be also achieved by introducing prestress in hollow core slabs. but the evaluation of shear strength of precast-prestressed hollow core slabs are needed because the cross section is reduced in web and arranging shear reinforcement is not possible. In this study, the shear strength of precast-prestressed hollow core slabs were evaluated based on experimental tests. For this purpose, six full scale specimens were made and tested. The shear strength of the specimens were compared with those evaluated from current design provision(EC2 ACI, EN1168 and AASHTO).

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.1
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• pp.1-7
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• 2003

The carbon composite tube can play an important role in replacing or complementing longitudinal and transverse reinforcing steels by providing ductility and strength for conventional columns. In this study, both the experimental and analytical investigations of axial behavior of large-scale square concrete columns confined by carbon composite tube are presented. The specimens are filament-wound carbon composite with 90$^{\circ}$+30$^{\circ}$, 90$^{\circ}$+45$^{\circ}$ winding angle respect to longitudinal axis of tube. The instrumented large-scale concrete-filled composite tubes(CFCT) are subjected to monotonic axial loads exerted by 10,000kN UTM. The influence of winding angle, thickness of tube on stress-strain relationships of the confined columns is identified and discussed. Proposed equations to predict both the strength and ductility of confined columns by carbon composite tube demonstrate good correlation with test data obtained from large-scale specimens.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.2
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• pp.155-162
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• 2012

Recently, building of long span bridge is increasing and cable stayed bridges have large portion in civil projects. As the spans of bridges become longer, steel cable-stayed bridges have been constructed mainly for slim structure. But in many case, pylons are constructed by concrete for the stability of structures and the economy. Concrete is greatly influenced by the long-term behavior like creep and drying shrinkage, so analysis of stress redistribution and structural change in construction is required. In this study, as a cable stayed bridge with concrete pylon, Incheon Bridge is analyzed by nonlinear FEM analysis program RCAHEST. Through this analysis, time dependent effect of concrete pylon to whole cable stayed bridge system is studied.

• Magazine of the Korea Concrete Institute
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• v.9 no.2
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• pp.167-177
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• 1997

In thtx design of ductile moment -1csist1ng frnmcls (DMRFs) f'ollow~ng the. stlong columnweakbeam design philosophy, it is desirable that the joint and column remain essentiallyelastic in order to insure proper energy dissipation and lateral stability of the structure.Thv joint has been identifid as the "weak link: in DMRFs because any stiffness orstrength deterioration in this region can lead to substantial drifts and the possibility ofcollapse due to t'-delta effects. h3oreove1.. the tngintw is faced with the difficult task ofdetailing an element whose size is determined by theframing members, but \vhich mustresist a set of loads very different from those used in the design of the beams and columns.Four 3 -scale beam-column-slab joint assemblies were designed according to existing cod\ulcornerrequirements of' ACI 318-89. representing perimeter joints of DMRFs with reinforced highstrength concrete. The influence on aseismic behavior of beam-column joints due tomonolithic slab, has been investigated.lab, has been investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.261-264
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• 2008

When the concrete is confined to width direction, stress-strain curve of concrete are different from the uniaxial behavior. In case of normal strength concrete, Mander model are used with concrete material model which considers confining effect. Sakino-Sun model showed experimental result of specimen-level and the highest accuracy. Therefore, Normal strength concrete used Mander model. and High strength concrete used Sakino-Sun model. But there are significant differences from actual data when medium strength concrete used Mander or Sakino-Sun model. and Limit scope of maximum or minimum compressive strength of concrete is not clear when applied to two models. Therefore, In this research, material nonlinear model of confined concrete is suggested when concrete which has 30-40MPa's strength is confined to width direction.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.169-172
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• 2008

Carbon fiber reinforced polymer (CFRP) laminates can be used more efficiently in strengthening applications by applying prestress to the CFRP laminates. A key problem for prestressing with CFRP laminates is anchoring the laminates. These may include fracture to the CFRP laminates due to excessive gripping force or slippage of the CFRP laminates out of the anchorage zone caused by low friction between the anchor device and the lamiantes. The main objective of this study is the development of an applicative mold-type anchorage system for prestressed CFRP laminates through experimental study. The experimental parameters were the type of anchorage detail and the effect of surface treatment. The test results showed that the developed anchor assures 100% CFRP laminate strength.

• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.83-91
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• 2002

A common form of construction for apartment buildings consists of walls and coupling elements. But, the structural behavior of coupling elements are very complex and affected by the properties of coupling elements. The objective of this study is to estimate the behavior of coupling elements in wall-dominant systems. For the purpose of this study, two wall-slab specimens and two wall-beam specimens were tested. The specimens with different reinforcement layouts were subjected to reversed cyclic loading, consistent with coupling action, with increasing imposed inelastic deformations. From the results of this study, 1) in coupling slabs, the stresses were not uniform across the width, 2) the effective width of coupling slabs was found smaller than that of predicted from previous studies, 3) diagonally reinforced coupling beam with slab showed larger ductility and more amount of energy dissipation to be attained compared with conventionally reinforced coupling beam.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3602-3609
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• 2015

HPFRCC is characterized by a very low water-to-binder ratio which induce extremely large autogenous shrinkage at early age. The restriction of such autogenous shrinkage through the use of forms and reinforcing bars will increase substantially the risk of excessive residual stresses and shrinkage cracking. The exact understanding of the shrinkage behavior and studies on solutions to reduce shrinkage should be imperatively undertaken for further application of HPFRCC to real structures. Therefore, this paper investigated the mechanical properties of HPFRCC with respect to the eventual introduction of expansive admixture(EA) and shrinkage reducing agent (SRA) in the mixture. Autogenous shrinkage test was conducted considering the coefficient of thermal expansion (CTE) measured at early age so as to examine the effects of EA and SRA on the autogenous shrinkage behavior of HPFRCC.