• Journal of the Korea institute for structural maintenance and inspection
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• 제4권1호
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• pp.139-145
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• 2000

In this experimental program specimens. designed by the test variables, such as percentage of steel fiber incorporated, were constructed and tested to evaluate the flexural performance of reinforced steel fiber concrete beams. Based on the test results reported in this study, the following conclusions are made. Comparing with the load-displacement relationship of standard specimen, specimen over 0.5% of steel fiber incorporated, could be improved significantly flexural performance, such as capacity, ductility, and crack pattern. As increasing in quantity of steel fiber incorporated(0.5%~2.0%), the flexural strength of each specimen was shown the enhancement of 13%~40% in comparision with the standard specimen BSS.

• Proceedings of the Korean Institute of Building Construction Conference
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.23-24
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• 2023

In this study, an easily recyclable separable glued-laminated timber (GLT)-steel beam was developed, and a structural design method was presented. The GLT and steel were mechanically composited using self-tapping screws. The GLT-steel beam was designed to fail in the compression of GLT. The bending moment and load-carrying capacity of the GLT-steel beam were predicted based on composite beam theory and compared with experimental test data. As a result, the GLT-steel beam exhibited ductile behavior, and compression failure of GLT was observed. The screw connection showed no damage while the steel plate was extended. The load-carrying capacity of GLT after failure was similar to the load resistance predicted by the compressive strength of GLT and the tensile strength of steel. This indicates that the ductile behavior of the GLT-steel beam can be safely designed by the tensile strength (yield) of steel.

• Journal of Korean Society of Steel Construction
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• 제26권4호
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• pp.335-348
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• 2014

For high-strength steel, it is difficult to be applied to flexible structural member because it have high yield ratio and low basic material's toughness. One of the great problems when using high-strength steel connections is the brittle fracture at the end of the beam member in common with general mild steel connections. In the cases of mild steel connections, it has be developed that special moment frame connection details by reinforcing structural member or improvement of welding access hole. But, it is incomplete at yet about applicability estimation of high-strength steel connections. This study is the initial step research for the applicability estimation of beam-to-column connections being applied to developed high-strength steel, HSA800. And, it studied about structural performance of the high-strength steel connections according to the details of welding access hole through full-scale test and analytical method.

• Journal of the Korea Concrete Institute
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• 제25권1호
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• pp.11-18
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• 2013

Cement concrete pavement offers long-term service life and excellent applicability for heavy traffic. It is easier to purchase and more durable and economical than the asphalt pavement. However, it is difficult to repair and rehabilitate compared to the asphalt pavement when it comes to the maintenance problem. Since the crack is the main reason of the damage of concrete pavement, it is necessary to control the early and long-term crack in the concrete pavement. In this experimental study, the basic performance tests have been carried out to investigate the effect of hybrid fibers which were composed of micro fibers with small diameter and high aspect ratio and macro fibers with large diameter and low aspect ratio on the concrete pavement, in which lower water ratio and larger aggregates were used compared to the general concrete mixture. The test results showed that the flexural strength and toughness of concrete pavement mixture have been increased with the use of hybrid fibers in the concrete pavement mixture, even though they were less effective compared to the normal concrete mixture. It was found that the hybrid fibers were effective to control the early shrinkage of the concrete pavement which is one of the main reasons of the damage in the concrete pavement.

• Journal of the Korea Concrete Institute
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• 제24권2호
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• pp.165-172
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• 2012

In this study, the physical, mechanical, structural, and environmental performances based on field measured data were evaluated to check the suitability of concrete for ecological preservation and cultivation of a hydrophilic environment. More specifically, the study is focused on developing an environmentally friendly functional concrete with river ecology restoration and natural river early formation capabilities. The mechanical performance evaluation results showed that the increase in mix rate of the PVA (Poly Vinyl Alcohol) reinforcement fibers and silica fume caused an increase in the strength. The optimal mix rate was found to be 0.05 volume % PVA fiber and approximately 10% silica fume. The frost resistance evaluation showed that superior performance was gained when 0.05 volume % PVA fiber and 15% silica fume was mixed simultaneously. In the structural performance evaluation, the bending strength was improved by 47.7% compared to plain concrete when mixed with 0.05 volume % PVA fiber. The flexural toughness also saw significant improvement. The environmental monitoring of field performance showed that grasses germinated most rapidly, but the growth of red poppies, a plant that germinates in the spring, was most active with passing of time. Coverage measurements in all of the monitoring locations found favorable coverage of over 95% after 12 weeks. The study results showed that the environmentally friendly functional concrete had outstanding environmental performance.

• Journal of the Korea Institute of Building Construction
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• 제16권3호
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• pp.201-209
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• 2016

This study is to examine experimentally on the engineering properties of fiber reinforced concrete using kenaf(KN) fiber and another organic fibers for comparing test, and propose the usable method of KN fiber as an natural fiber in the concrete industry. It is to select 4 contents(0, 0.3, 0.6 and $0.9kg/m^3$) of KN fiber and 4 organic fibers (Jute, Cellulose, Polypropylene and Nylon). For this study, it is to perform various tests including slump, air content, plastic and drying shrinkage, flexural and tensile strength, carbonation depth for the fiber reinforced concrete according to contents of KN fiber and 4 organic fibers. The results of this study are as follows : In case of KN fiber contents $0.6kg/m^3$, it shows the effective results from increasing concrete strength including flexural and tensile, from decreasing plastic and drying shrinkage, carbonation depth. Also KN fiber is confirmed having excellent performances by comparing with test results of another organic fibers as same contents $0.6kg/m^3$. Therefore, considering concrete test results, cost and environment, KN fiber is proposed as the optimum contents in the range of $0.6kg/m^3$ and an effective fiber materials, and needs to keep up these study on the site application.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제38권1호
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• pp.11-18
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• 2018

As the amount of polycarboxylate superplasticizer varied from 1.2% to 3.0% of the mass of binder, the change in the flowability & rheological properties, and strength of UHPFRC was investigated with experiments. The test results presented that the increase in the amount of superplasticizer was effective in improving the flowability up to 1.8%, but addition more than 1.8% was hardly beneficial for enhancing the flowability and rhelogical properties. Compressive strengths with different amounts of superplasticizer showed that the strength with 1.8% was slightly higher than that of 1.2%, but the amount more than 1.8% caused strength reduction, which was higher as the amount increased. The results in flexural strength according to the amount of superplasticizer showed a similar trend with the results in compressive strength. When the effect of compressive strength and fiber distribution characteristics on the flexural strength was analysed separately, it was found that high amount of superplasticizer caused an effect of fiber distribution in addition to the effect of compressive strength on flexural strength. This effect seems to be closely related to the results of flowability or rheological properties.

• Journal of the Korea Concrete Institute
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• 제16권6호
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• pp.759-766
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• 2004

The addition of steel fiber with concrete significantly improves the engineering properties of structural members, notably shear strength. The purpose of this study is to determine the steel fiber shape, aspect ratio and volume fraction ratio in a point of practical usage as structural members. Steel fiber factor and volume fraction are also considered to verify the strengthening effect in member level. From the reviewing of previous researches and analyzing of consecutive material test results, the optimum shape and length of steel fiber, which can have a good strengthening effects were defined as a hooked end type and larger than 1.5 times of maximum gravel size. Analyzing the test results of strength and deformation capacity, aspect ratio 75 and volume fraction $1.5\%$ can be having a maximum strengthening effect of steel fiber. Also steel fiber factor, tensile splitting strength, and flexural strength are found as key parameter in shear strengthening effect in member level.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제28권4A호
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• pp.581-590
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• 2008

The panels are used as a composite part of the completed deck. They replace the main bottom transverse deck reinforcement and also serve as a form surface for the cast-in-place concrete upper layer that contains the top of deck reinforcement. In this paper, three types of the detail for joints was selected and their structural performance in terms of strength and crack contral was investigated through static tests on composite beams. Form the results, the validity of loop joints for continuity of half-depth precast deck was observed and especially an overlapping length of loop joint and transverse reinforcement were checked. The results suggest that increasing the loop overlapping length increases the flexural strength of half-depth precast deck with loop joints. In terms of crack contral, the loop joint with transverse reinforcement showed better performance.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.465-468
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• 2008

SHCCs (Strain Hardening Cement Composites) show the high energy tolerance capacity due to the interfacial bonding of the fibers to the cement matrix. For effective material design and application of SHCCs, it is needed to investigate the compression, four-point bending, direct tensile response of SHCCs with different types of fibers and water-cement ratio. For these purposes, three kinds of fibers were used: PP(polypropylene, 2.0%), PVA(Polyvinyl alcohol, 2.0%), PE (Polyethylene, 1.0%). Also, effects of water-cement ratio(0.45, 0.60) on the SHCCs were evaluated in this paper. As the result of test, SHCCs with PVA and PE fiber were showed better overall behavior than specimens with PP fibers on bending and direct tensile test. Also, for the same type of fiber, SHCCs with water-cement ratio of 0.45 exhibited higher ultimate strength than specimen with water-cement ratio of 0.60 on compression strength, and showed the multiple cracking on bending and direct tensile test. Therefore, to improve of workability and dispersibility of SHCCs on water-cement ratio of 0.60, continual studies were needed.