• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.165-172
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• 2021

The purpose of this study is to investigate the carbon capture capacity of various inorganic materials. For this purpose, the change in property of ordinary Portland cement (OPC), blast furnace slag fine powder (GGBS), and circulating fluidized bed boiler ash (CFBC) due to carbonation were analyzed. Carbonation curing was performed on all specimens through the accelerated carbonation experiment, and the amount of carbon capture was quantitatively analyzed by thermogravimetric analysis according to the age of carbonation. From the results, it is confirmed that the carbon capture capacity was shown in all specimens. The carbon capture amount was shown in the order of CFBC, OPC, and GGBS. The 28-day carbon capture of CFBC, OPC, and GGBS was 3.9%, 1.3%, and 9.4%, respectively. Carbon capture reaction occurred rapidly at the beginning of carbonation, and occurred slowly with increasing age. SEM image analysis revealed that an additional product generated by carbonation curing in all specimens was calcium carbonate.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.95-102
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• 2021

Elastometic bearings using flexible rubber materials have recently been widely applied for seismic retrofit of bridges. However, due to various factors, the aging of the rubber material progresses, which causes the shear stiffness change of the bearing, which affects the seismic performance of the bridge. For natural rubber, accelerated heat aging test was performed with variables of heating temperatures and exposure time to analyze shear characteristics. As aging progresses (i.e. increase of temperature and exposure time), the maximum shear stress and shear strain decrease. Also, the shear stiffness is greatly increased at the same shear strain. This means that the rubber material is hardened, implying that the seismic performance of the elastomeric bearing becomes poor.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.105-112
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• 2023

Steel fiber reinforced concrete (SFRC) exhibits enhanced strength and superior energy dissipation capacity compared to normal concrete, and it can also reduce crack propagation and fragmentation of concrete even when subjected to blast loads. In this study, the parameters defining failure surface and damage function of the K&C concrete nonlinear model were proposed to be applied for the properties of SFRC in LS-DYNA. Single element analysis has been conducted to validate the proposed parameters in the K&C model, which provided very close simulations on the compressive behavior of SFRC. In addition, blast analysis was performed on SFRC columns with different volume fractions of steel fibers, and the blast resistance of SFRC columns was quantitatively analyzed with Korea Occupational Safety & Health Agency (KOSHA) guidelines.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.123-130
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• 2006

The duties of the restorative materials are to bear up against stress and to protect reinforcement corrosion. So the restorative materials are estimated by various kinds of strength, permeability and etc, But, in case of existing performance evaluation of restorative materials, because various deterioration factors are separately acted, the system of performance evaluation is different from that of combined deterioration of real structure and it is difficult to evaluate the exact performance of restorative materials. In this study, to evaluate Performance of restorative materials, we compare their korea standard properties in terms of compressive and bending strength and permeability of water and air with real durability for carbonation, salt damage and actual reinforcement corrosion like ratio of corrosion area. weight reduction and corrosion velocity of steel bar under environment of combined deterioration. The results showed that strength and permeability of restorative materials are similar but their resistance to carbonation, salt damage and actual reinforcement corrosion are very different.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.3
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• pp.97-105
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• 2006

The autogenous shrinkage of high-performance concrete is important in that it can lead the early cracks in concrete structures. The purpose of the present study is to explore the autogenous shrinkage of high-performance concrete with admixture and to derive a realistic equation to estimate the autogenous shrinkage model of that. For this purpose, comprehensive experimental program has been set up to observe the autogenous shrinkage for various test series. Major test variables were the type and contents of admixture and water-cement ratio is fixed with 30%. The autogenous shrinkage of HPC with fly ash slightly decreased than that of OPC concrete, but the use of blast furnace slag increased the autogenous shrinkage. Also, the autogenous shrinkage of HPC is found to decrease with increasing shrinkage reduction agent and expansive additive. A prediction equation to estimate the autogenous shrinkage of HPC with admixture was derived and proposed in this study. The proposed equation show reasonably good correlation with test data on autogenous shrinkage of HPC with mineral and chemical admixture.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.143-150
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• 2008

There is possibility of poor-state concrete filling condition due to segregation of aggregate and paste in reinforced concrete structure. This study was conducted to evaluate the flexural and shear behavior of reinforced concrete beams with different concrete filling conditions. Different concrete filling conditions were intentionally made such that the specimens was soundly cast to obtain the perfect concrete filling condition and cast in such a way that up to the longitudinal tensile reinforcement from the top, good concrete was filled while poor concrete was poured for the bottom part to simulate the poor strength, workability and unsatisfactory compaction. The test results indicate that have no effect of concrete filling conditions on the yielding strength of structures. But, have a great influence on the flexural ductility and shear capacity of structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.1
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• pp.77-84
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• 2007

In this paper presented, a design method of sandwich slab bridge of simple supported made by composite materials. Many of the bridge systems, including the girders and cross-beams, and concrete decks behave as the special orthotropic plates. Such systems with sections, boundary conditions other than Navier or Levy solution types, or with irregular cross sections, analytical solution is very difficult to obtain. Thus, Finite Difference Method is used for analysis of the pertinent problem. For the design of bridge made by the composite materials, cross-section is used the form-core shape because of this shape is economical and profitable, and for output of the stress value used F.D.M. Based the experimental of a composite specialist, an equation expressing the rate of decrease of tensile strength of glass fibers based on increase of mass was obtained. From these equations, one can estimate the rate of tensile strength reduction due to increased size. Tasi-Wu failure criterion for stress space is used. Strength-failure analysis procedure, using these reduced tensile strength, is presented.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.77-84
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• 2007

The elastic buckling strength of a corrugated pipe made of orthotropic material was evaluated. The height and length of a corrugated wave and the thickness of the pipe were considered as factors affecting the buckling strength of the pipe. And also, the ratio of the longitudinal stiffness and transverse stiffness were considered as parameters affecting on the buckling strength of a pipe made of orthotropic material. Buckling strengths of various corrugated pipes with different shapes and stiffness ratio were evaluated by FE analyses. And a formula to estimate the elastic buckling strength was suggested by regression of FE analysis results. Analysis results show that a corrugated pipe has superior buckling strength to a general flat pipe and the suggested formula estimates accurate buckling strength of the corrugated pipe made of orthotropic material.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.73-80
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• 2008

Experimental study has been performed in order to construct the standard test methods and appraisal criteria by investigating the influence of specimen types(property, width, layers) and loading rate on the tensile characteristics of FRP used in strengthening RC structures. The FRP composite tested in this study are the unidirectional CFRP sheet/strip and the bidirectional GFRP sheet. Test variables consist of the various width ranging from 10mm to 25mm and number of CFRP sheets plied up to 5 layers. Test results indicated that maximum tensile strength and minimum coefficient of variation are recorded at each different width according to the fiber types and weaving directions. Also, the average tensile strengths of CFRP sheets are decreased as the number of layer of CFRP sheet are increased.

• Magazine of the Korea Concrete Institute
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• v.14 no.3
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• pp.35-44
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• 2002

우리나라의 인구대비 년간 시멘트 소비량은 최근 10년 동안 평균 1.2ton/인ㆍ년 이상이며, 이는 OECD국가 중 최고의 시멘트 소비 수준인 것으로 알려져 있다. 시멘트ㆍ콘크리트는 강재와는 달리 생산량 전부가 건설재료로 사용되므로 시멘트ㆍ콘크리트가 차지하는 비중이 높고 소비량이 많다는 사실은 구조물의 사용단계에서 요구되는 유지관리비용 중 콘크리트 구조물의 비중이 상대적으로 높을 수밖에 없음을 의미한다.(중략)