• Computers and Concrete
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• 제20권1호
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• pp.23-29
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• 2017

In this study engineered steel fibres used as reinforcement for concrete were characterized by number of key mechanical and spatial parameters, which are easy to measure and quantify. Such commonly used parameters as length, diameter, fibre intrinsic efficiency ratio (FIER), hook geometry, tensile strength and ductility were considered. Effective classification of various fibres was demonstrated using simple multivariate computations involving principal component analysis (PCA). Contrary to univariate data mining approach, the proposed analysis can be efficiently adapted for fast, robust and direct classification of engineered steel fibres. The results have revealed that in case of particular spatial/geometrical conditions of steel fibres investigated the FIER parameter can be efficiently replaced by a simple aspect ratio. There is also a need of finding new parameters describing properties of steel fibre more precisely.

• 한국안전학회지
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• 제25권6호
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• pp.155-160
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• 2010

In this study, detailed assessment for durability performance were performed on the chloride protected concrete structures to investigate the effectiveness of chloride protection. And economical efficiency for the chloride protected concrete structures were studied by LCC(Life Cycle Cost) analysis. In the comparison result of the first section repair time, it was found that the chloride protected concrete structures was economical better than the non-protected concrete structures in the long term. According to the analysis result of the accumulated chloride concentration by used time and chloride ion concentration by depth, it can be seen that the permeation through time from chloride has increased two times in the chloride protected concrete structures.

• Computers and Concrete
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• 제16권2호
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• pp.275-285
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• 2015

This paper reports the results of an experimental study on the compressive strength and the stress-strain curve (SSC) of recycled fine glass aggregate concrete with different replacement percentages of recycled fine glass aggregate. The results show that the recycled fine glass aggregate contents have significant impact on the workability, compressive strength, the elastic modulus, the peak and the ultimate strains of recycled fine glass aggregate concrete. Analytical expressions for the stress-strain relationship of recycled fine glass aggregate concrete are given, which can satisfactorily describe the effect of the recycled fine glass aggregate on the SSC.

• Advances in concrete construction
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• 제9권1호
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• pp.9-22
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• 2020

The present work looks at the possibilities of recycling more than once demolished concrete as coarse aggregates, to produce new concrete. Different concrete mixes were made with substitutions of 50%, 75% and 100% of recycled concrete aggregates respectively as coarse aggregates. The physico-mechanical characterization tests carried out on the recycled concrete aggregates revealed that they are suitable for use in obtaining a structural concrete. The resulting concrete materials had rheological parameters, compressive strengths and tensile strengths very slightly lower than those of the original concrete even when 100% of two cycles recycled concrete aggregates were used. The durability of the recycled aggregates concrete was assessed through water permeability, water absorption and chemical attacks. The obtained concretes were thought fit for use as structural materials. A linear regression was developed between the strength of the material and the number of cycles of concrete recycling to anticipate the strength of the recycled aggregates concrete. From the results, it appear clear that recycling demolished concrete represents a valuable resource for aggregates supply to the concrete industry and a the same time plays a key role in meeting the challenge for a sustainable development.

• Computers and Concrete
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• 제11권2호
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• pp.169-182
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• 2013

One of the major benefits of the pre-stressed concrete pavements is the omission of tension in concrete that results in a reduction of cracks in the concrete slabs. Therefore, the life of the pavement is increased as the thickness of the slabs is reduced. One of the most important issues in dealing with the prestressed concrete pavement is determination of the magnitude of the pre-stress. Three dimensional finite element analyses are conducted in this research to study the pre-stress under various load (Boeing 777) and thermal gradient combinations. The model was also analyzed under temperature gradients without the presence of traffic loading and the induced stresses were compared with those from theoretical relationships. It was seen that the theoretical relationships result in conservative values for the stress.

• Advances in concrete construction
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• 제2권2호
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• pp.77-89
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• 2014

The properties of fresh and hardened concrete made using three types of artificial cold bonded aggregates are determined. The properties, namely, slump, water absorption, compressive strength and splitting tensile strength of concrete containing artificial aggregate are reported. The variables considered are aggregate type and water-to-cement ratio. Three types of cold bonded aggregates are prepared using fly ash and quarry dust. The water-to-cement ratio of 0.35, 0.45, 0.55 and 0.65 is used. The test result indicates that artificial aggregates can be recommended for making the concrete up to a strength grade of 38 MPa. The use of quarry dust in the production of artificial aggregate mitigates environmental concerns on disposal problems of the dust. Hence, the alternate material proposed in this study is a green technology in concrete production.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.4-5
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• 2018

Recently, high-strength concrete used for shortening the construction time of high-rise building construction, Concrete pumping technology is emerging as the core technology of high-rise buildings. In this paper, we have started to study the use of electromagnetic field as a method to increase the efficiency of the lubricating layer between the inside of the pipe and concrete, which has been established as the most important factor determining the pumping performance. The pumping performance improvement effect of concrete strength was verified and basic research was carried out to utilize it as a method to increase the efficiency of pumping in field application. In the related work, the effect of the electromagnetic field was verified by conducting a mock-up performance evaluation (horizontal 300 m) of the pumping force by the concrete strength.

• Earthquakes and Structures
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• 제7권5호
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• pp.627-645
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• 2014

Using OpenSees as a framework, constitutive models of reinforced, prestressed and prestressed steel fiber concrete found by the panel tests have been implemented into a finite element program called Simulation of Concrete Structures (SCS) to predict the seismic behavior of shear-critical reinforced and prestressed concrete structures. The developed finite element program was validated by tests on prestressed steel fiber concrete beams under monotonic loading, post tensioned precast concrete column under reversed cyclic loading, framed shear walls under reversed cyclic loading or shaking table excitations, and a seven-story wall building under shake table excitations. The comparison of analytical results with test outcomes indicates good agreement.

• Structural Engineering and Mechanics
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• 제45권6호
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• pp.723-740
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• 2013

This paper presents a parametric study of reinforced concrete bridge tall piers with hollow, rectangular sections. Such piers are typically used in railway construction of prestressed concrete viaducts. Twenty one different piers have been studied with seven column heights of 40, 50, 60, 70, 80, 90 and 100 m and three types of 10-span continuous viaducts, whose main span lengths are 40, 50 and 60 m. The piers studied are intermediate columns placed in the middle of the viaducts. The total number of optimization design variables varies from 139 for piers with column height of 40 m to 307 for piers with column height of 100 m. Further, the results presented are of much value for the preliminary design of the piers of prestressed concrete viaducts of high speed railway lines.

• Computers and Concrete
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• 제23권6호
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• pp.459-470
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• 2019

Apart from strength properties, durability, toughness and workability are also important criteria in defining the performance of a concrete structure. Hence "High Performance Concrete (HPC)" is introduced. It is different from high strength concrete and can have various applications. In this paper, the properties (Mechanical and Durability) of High Performance Concrete blended with bagasse ash at 5%, 10%, 15% and 20% are studied. However, it is difficult to analyze the performance based on different properties obtained from different experiments. Hence it is necessary to combine all the criteria/properties into a single value to obtain a result by a technique called Analytical Hierarchy Process (AHP).It is an effective tool for dealing with complex decision making, and may aid the decision maker to set priorities and make the best decision. In addition, the AHP incorporates a useful technique for checking the consistency of the decision maker?s evaluations, thus reducing the bias in the decision making process.