• Computers and Concrete
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• v.16 no.1
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• pp.1-16
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• 2015

The proposed techniques to strengthen concrete members such as steel plates, polymers or concrete have important deficiencies in adherence and durability. The use of UHPFC plates can overtake effectively these problems. In this paper, the possibility of using UHPFC to strengthen RC beams under torsion is investigated. Four specimens of concrete beams reinforced with longitudinal bars only were tested under pure torsion. One of the beams was considered as the baseline specimen, while the others were strengthened by ultra-high-performance fiber concrete (UHPFC) on two, three, and four sides. Finite element analysis was conducted in tandem with experimental work. Results showed that UHPFC enhances the strength, ductility, and toughness of concrete beams under torsional load, and that finite element analysis is in good agreement with the experimental data.

• Composites Research
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• v.24 no.5
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• pp.29-33
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• 2011

The application of high performance materials for the deck can represent a fair alternative to reduce the weight of the deck and improve the econimic efficiency of the bridge even if high performance materials are costly. In UHPC(Ultra High Performance Concrete) bridges, it is necessary to verify that exiting headed stud can be used to transfer longitudinal shear forces across the steel-concrete interface. In this paper, the push-out tests are performed to analisys the composite behavior between UHPC bridge deck and steel girder. The ultimate strength of test specimens is proportional to the diameter of headed studs in push-out test for static loading. Test results show that the shear strength of headed stud is improved for the case of normal concrete bridge decks.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.25-26
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• 2018

Various concrete material technologies and new materials have been developed in accordance with the advancement of buildings. As part of these new technologies, light transparent concrete, which was invented by Hungarian architect Aron Losonczi and attracted worldwide attention, has a technique of arranging optical fiber inside concrete and transmitting the light from exterior to concrete to show silhouette inside. However, due to many disadvantages, application to the field was limited and commercialization was not easy. In Korea, Light Emotion Friendly Concrete has been developed for commercialization. In order to solve the degradation of construction performance caused by the arrangement of expensive optical fiber, which is pointed out as a disadvantage of translucent concrete, It converts expensive fiber into low cost acrylic rod, easy to arrange, pre-assembled to form and post-cast. Therefore, this study aims to improve the mechanical properties of LEFC and to derive optimal combination.

• International Journal of High-Rise Buildings
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• v.13 no.2
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• pp.187-194
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• 2024

The 53-meter tall Albizzia Tower is a white, mineral building with a mixed concrete and wood structure. It harmoniously interacts with the high rises of La Confluence. Its base is largely open, in direct relation to the public space. The spaces are mutable, reversible, moldable thanks to a streamlined structure: posts, beams in glued laminated wood, with posts pushed back on the facade to facilitate the layout of office and housing floors, CLT floors with a span of 7 meters.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.110-118
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• 2010

This research dealt with the effect of steel-fiber reinforcement on the compressive strength of ultra high performance cementitious composites (UHPCC) and compared with that in normal steel-fiber reinforced concrete(SFRC). With wide range of compressive strength of UHPCC, experiments on the fiber reinforcement effect confirmed that the compressive strength in UHPCC is also improved by adding fibers as in normal SFRC. The experimental results were compared with previous researches about reinforcement effect by adding fibers, which are limited within 100MPa compressive strength. The comparison revealed the linear relationship between $f'_{cf}-f'_c$ and RI regardless of the magnitude of compressive strength, from which a general equation to express the effect of fiber reinforcement, applicable to various SFRC's with wide range of compressive strength including UHPCC.

• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.223-234
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• 2016

In this study, direct tension test for hybrid steel fiber reinforced ultra-high performance concrete (UHPC) containing two different steel fibers with a length of 16 and 19 mm was performed to investigate the fracture behavior of UHPC. Test results showed that crack strength and tensile strength, and fracture energy increased with increasing the fiber volume ratio. Based on the test results, the peak cohesive stress at the crack tip, tensile strength, and fracture energy depending on the fiber volume ratio were proposed. The proposed tensile strength of UHPC was suggested as a function of the fiber volume ratio and compressive strength. The peak cohesive stress at the crack tip and fracture energy were also proposed as a function of the tensile strength. The predicted values were relatively agree well with the test results. Thus, the proposed equations is expected to be applicable to UHPC with a compressive strength of 140~170 MPa and a fiber volume ratio of less than 2%.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.353-356
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• 2008

UHPC which was a structural material exhibiting very remarkable mechanical performances with compressive strength, tensile strength and flexural strength rising up to 200MPa, 15MPa and 35MPa, respectively. In addition, this material presents exceptional durability regard to the very low diffusion and penetration speeds of noxious substances like chloride ions This study was carry out to evaluate the effect of flexural behavior according to steel fiber type in UHPC. The results is showing that the steel fiber type have remarkable influence flexural strength Addition to it is showing that steel fiber type made little difference in the first cracking strength but considerable gap in the ultimate flexural strength to use the steel fiber of wave type.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.9-15
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• 2011

The flexural behavior of the UHPFRC rectangular beam which has 100 MPa, 140 MPa compressive strength were compared with that of the typical RPC rectangular beam which has same geometrical shape, prestressd force and 160 MPa compressive strength. UHPFRC beam was not reinforced at all and the variable of test is fraction of steel fiber, compressive strength of concrete, method of prestressing and ratio of prestressing bar. The behavior of UHPFRC beam was analysed by relationship of moment - curvature and load - deflection. Simple modeling of stress-strain of UHPFRC was proposed. Based on the proposed constituted, the flexural moment-curvature relationship was calculated and compared with experimental data on prestressed UHPFRC beams. Good agreement between calculated strengths and experimental data is obtained.

• Advances in concrete construction
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• v.8 no.2
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• pp.101-117
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• 2019

Structural strengthening of reinforced concrete (RC) beams is becoming essential to meet the up-gradation of existing structures due to the infrastructure development. Strengthening is also essential for damaged structural element due to the adverse environmental condition and other distressing factors. This article reviews the state of the field on repair, retrofitting and rehabilitation techniques for the strengthening of RC beams. Strengthening of RC beams using various promising techniques such as externally bonded steel plates, concrete jacketing, fibre reinforced laminates or sheets, external prestressing/external bar reinforcement technique and ultra-high performance concrete overlay have been extensively investigated for the past four decades. The primary objective of this article is to discuss investigations on various strengthening techniques over the years. Various parameters that have been discussed include the flexural capacity, shear strength, failure modes of various strengthening techniques and advances in techniques over the years. Firstly, background information on strengthening, including repair, retrofitting, and rehabilitation of RC beams is provided. Secondly, the existing strengthening techniques for reinforced concrete beams are discussed. Finally, the relative comparisons and limitations in the existing techniques are presented.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.57-65
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• 2022

This study investigated the electromechanical response of smart ultra-high performance fiber reinforced concretes (S-UHPFRCs) under flexural loading to evaluate the self-sensing capacity of S-UHPFRCs in both tension and compression region. The electrical resistivity of S-UHPFRCs under flexural continuously changed even after first cracking due to the deflection-hardening behavior of S-UHPFRCs with the appearance of multiple microcracks. As the equivalent bending stress increased, the electrical resistivity of S-UHPFRCs decreased from 976.57 to 514.05 kΩ(47.0%) as the equivalent bending stress increased in compression region, and that did from 979.61 to 682.28 kΩ(30.4%) in tension region. The stress sensitivity coefficient of S-UHPFRCs in compression and tension region was 1.709 and 1.098 %/MPa, respectively. And, the deflection sensitivity coefficient of S-UHPFRCs in compression region(30.06 %/mm) was higher than that in tension region(19.72 %/mm). The initial deflection sensing capacity of S-UHPFRCs was almost 50% of each deflection sensitivity coefficient, and it was confirmed that it has an excellent sensing capacity for the initial deflection. Although both stress- and deflection-sensing capacity of S-UHPFRCs under flexural were higher in compression region than in tension region, S-UHPFRCs are sufficient as a self-sensing material to be applied to the construction field.