• Title/Summary/Keyword: impact tests

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Experimental investigation on self-compacting concrete reinforced with steel fibers

  • Zarrin, Orod;Khoshnoud, Hamid Reza
    • Structural Engineering and Mechanics
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    • v.59 no.1
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    • pp.133-151
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    • 2016
  • Self-Compacting Concrete (SCC) has been originally developed in Japan to offset a growing shortage of skilled labors, is a highly workable concrete, which is not needed to any vibration or impact during casting. The utilizing of fibers in SCC improves the mechanical properties and durability of hardened concrete such as impact strength, flexural strength, and vulnerability to cracking. The purpose of this investigation is to determine the effect of steel fibers on mechanical performance of traditionally reinforced Self-Competing Concrete beams. In this study, two mixes Mix 1% and Mix 2% containing 1% and 2% volume friction of superplasticizer are considered. For each type of mixture, four different volume percentages of 60/30 (length/diameter) fibers of 0.0%, 1.0%, 1.5% and 2% were used. The mechanical properties were determined through compressive and flexural tests. According to the experimental test results, an increase in the steel fibers volume fraction in Mix 1% and Mix 2% improves compressive strength slightly but decreases the workability and other rheological properties of SCC. On the other hand, results revealed that flexural strength, energy absorption capacity and toughness are increased by increasing the steel fiber volume fraction. The results clearly show that the use of fibers improves the post-cracking behavior. The average spacing of between cracks decrease by increasing the fiber volume fraction. Furthermore, fibers increase the tensile strength by bridging actions through the cracks. Therefore, steel fibers increase the ductility and energy absorption capacity of RC elements subjected to flexure.

A Feasibility Study of Wood-plastic Composite Paver Block for Basic Rest Areas

  • Yang, Sungchul
    • Journal of the Korean Wood Science and Technology
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    • v.47 no.1
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    • pp.51-65
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    • 2019
  • A wood-plastic composite (WPC) paver block was manufactured using wood chips waste through an extrusion process, and it was intended to be used for paving in basic rest areas. The first stage in this study covered preliminary tests in terms of flexural strength and dimensional swelling to determine the optimal WPC compounding mix condition, by variation of the WPC ingredients. Next, three different paver blocks including the WPC block, a non-porous cement block, and a porous cement block were tested in terms of various material properties in the laboratory. Finally, two outdoor test sections of the proposed paver blocks were prepared to simulate a basic rest area. Test results indicated that the flexural strength of the WPC paver blocks was about 1.6 times greater than that of the tested cement paver blocks. The WPC block pavement was unaffected by water buoyance as well as volume expansion due to swelling. Results from the impact absorbance test and light falling weight deflectometer (LFWD) test clearly showed that the WPC block paving system marginally satisfied the comfortable and safe hardness range from the pedestrians' perspective, while the results demonstrated that it is structurally sound for application as a road paving block.

Impact Characteristics of AFRP Reinforced Concrete Slab (AFRP 보강 콘크리트 슬래브의 충격 특성에 관한 연구)

  • Park, Sung-Jin
    • Journal of the Society of Disaster Information
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    • v.14 no.4
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    • pp.492-500
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    • 2018
  • Purpose: In this paper, based on this background, the main purpose of studying the behavior of concrete slab reinforced with new material fiber in impact loading is investigated by AFRP using aluminum fiber. Results: Research on the use of new materials as reinforcing materials for concrete members has been carried out in many fields such as flexural and shear tests under static loading, fatigue loading under cyclic loading, and application to PC beams. However, And the issue of plate elements is still at a basic stage. Conclusion: In this paper, the dynamic behavior of reinforced concrete slabs is investigated by using AFRP rod reinforced with aluminum fiber.

How YouTube Influencers Impact Customers' Purchase Intention: An Empirical Study of Cosmetic Brands in Vietnam

  • LE, Thanh Vi;ALANG, Tho;TRAN, Quang Tri
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.9
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    • pp.101-111
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    • 2021
  • This study investigates the impact of heuristic factors on customers' perception of information credibility of influencers on YouTube channels, and the association between customers' perception of information credibility and brand attitude, brand credibility, and purchase intention of cosmetic products in Vietnam. A quantitative approach is employed, with a survey of 270 females who are frequent viewers of beauty content on YouTube channels. The data reliability and validity go through various statistical tests including exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). Also, structural equation modeling (SEM) is applied to test the hypotheses. The results reveal that there is a positive association between heuristic factors and the perception of information credibility. This perception of information credibility also influences positively on customers' attitudes toward the brand and brand credibility. Purchase intention is also found to be positively associated with the two latter variables. The study's main findings not only offer advice to practitioners on how to choose the right product endorsers and advertising platforms, but they also offer novel insight from the Vietnamese context that could help to extend the heuristic-systematic model and customers' buy intention behavior.

Influence of Korean Celebrity Endorsement on Chinese Consumers' Purchase Intention towards Fashion Goods

  • Yu, Hua Cui;Yu, Ling Bai
    • Journal of Fashion Business
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    • v.24 no.6
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    • pp.148-158
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    • 2020
  • Korean celebrity endorsement is a common practice adopted by companies in China. This study assessed the impact of celebrity endorsement (trustworthiness, attractiveness, congruency, and expertise) on Chinese consumers' intention to purchase clothes endorsed by Korean celebrities. This study used reliability and validity tests and structural equation model analysis to explore the relationship between variables using SPSS 22.0 and AMOS 22.0. This study conducted an online survey (www.sojump.com) from August 10, 2020 to August 20, 2020 and collected 370 respondents. Results show that all constructs of celebrity endorsement positively affected purchase intention and that celebrity expertise had the strongest impact. With respect to the influence of demographic variables on the constructs, gender, age, and education had a significant effect on trustworthiness; gender and age had a significant effect on attractiveness; and income had an effect on purchase intention. Marketing executives should consider using Korean celebrities for different purposes in brand advertising. Particularly, celebrity expertise, such as experience, knowledge, and skills, should receive attention while publicizing to Chinese consumers. This study contributes to the academic and practical implications of Korean celebrity endorsement.

Study on Properties of Carbon Sheet Molding Compound(C-SMC) according to Resin and Carbon Fiber Ratio (수지 및 탄소섬유 함유량에 따른 C-SMC 복합재료 물성 연구)

  • Seo, Dae-kyung;Yang, Suk-gon;Kim, Ki Young;Park, Min Gee;Park, Dae-gyu;Lee, Eun-ha;Kim, Yong-tae;Bae, Jin-Seok
    • Textile Coloration and Finishing
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    • v.32 no.4
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    • pp.245-254
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    • 2020
  • The sheet molding compound composite has been applied divers section. This paper reports processing of carbon fiber reinforced thermosetting composite with diverse resins and which was composed of chopped carbon fiber (30 ~ 60 wt%). Normally the paste that the viscosity is over 15,000 cps has been used in traditional Sheet molding compound (SMC) machine. In this research, SMC machine was designed to make Carbon-sheet molding compound (C-SMC) prepreg which was composed with low viscosity resin (1,800 ~ 2,500 cps increase up to 10,000 cps after aging). In order to confirm the optimal processing condition. Mechanical strength tests including tensile test, shear test, impact test, flexural strength test were conducted on C-SMC composites. Plus we identified the correlation between the mechanical properties and prepreg processing condition (carbon ratio and applied resin).

Modified K&C Model for Numerical Analysis of Steel-Fiber-Reinforced Concrete Structure (강섬유 보강 콘크리트 구조물의 해석을 위한 K&C모델의 보정)

  • Park, Gang-Kyu;Lee, Minjoo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.34 no.2
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    • pp.85-91
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    • 2021
  • This paper introduces a modified Karagozian & Case concrete model (K&C model) for the numerical analysis of a steel-fiber-reinforced concrete (SFRC) structure subjected to projectile impact. The original K&C model was calibrated to consider the effects of steel fibers accurately by modifying the strength surfaces and input parameters. Single element tests were then conducted and compared with uniaxial and triaxial compressive data to verify the modified model. With the application of a dynamic increase factor, the finite element model of the SFRC structure subjected to projectile impact was constructed. Thereafter, the applicability of the modified material model was examined by comparisons with the experimental results.

Evaluating the asymmetric effects of nuclear energy on carbon emissions in Pakistan

  • Majeed, Muhammad Tariq;Ozturk, Ilhan;Samreen, Isma;Luni, Tania
    • Nuclear Engineering and Technology
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    • v.54 no.5
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    • pp.1664-1673
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    • 2022
  • Achieving sustainable development requires an increasing share of green technologies. World energy demand is expected to rise significantly especially in developing economies. The increasing energy demands will be entertained with conventional energy sources at the cost of higher emissions unless eco-friendly technologies are used. This study examines the asymmetric effects of nuclear energy on carbon emissions for Pakistan from 1974 to 2019. Augmented Dickey-Fuller (ADF) and Phillips Perron (PP) unit root tests suggest that variables are integrated of order one and bound test of Autoregressive Distributed Lag (ARDL) and nonlinear ARDL confirm a long-run relationship among selected variables. The ARDL, Fully Modified Ordinary Least Squares (FMOLS), and Dynamic Ordinary Least Squares (DOLS) results show that the coefficient of nuclear energy has a negative and significant impact on emissions in both short and long run. Further, the NARDL finding shows that there exists an asymmetric long-run association between nuclear energy and CO2 emissions. The vector error correction method (VECM) results indicate that there exists a bidirectional causal relationship between nuclear energy and carbon emissions in both the short and long run. Additionally, the impact of nuclear energy on ecological footprint has been examined and our findings remain robust.

Study on the High-Strength Air-Cushion Fabrics for Impact-Relief Application Prepared through Primer Coating and Thermal Film Laminating (프라이머 코팅과 열융착 필름 라미네이팅을 통해 제조한 충격 완화용 고강력 에어쿠션 직물에 관한 연구)

  • Kim, Ji Yeon;Kim, Hun Min;Min, Mun Hong
    • Textile Coloration and Finishing
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    • v.33 no.4
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    • pp.269-279
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    • 2021
  • In this study, the laminating of TPU film after coating of primer adhesive on the fabrics was applied in order to secure the strength to withstand a fall from a higher altitude by increasing the adhesion between the fabric and the film layer. It seems that the fineness of the yarn and the weave construction have a greater effect than the type of the laminating films. The order of superiority of the laminated fabrics by film type and thickness was the same for 1000 denier and 210 denier fabrics, and the tendency was consistent with the order of superiority in the film properties and peel strength tests. The tear strength of laminating fabrics increased three to four times for 1000 denier fabrics compared to the fabric alone, but it decreased by 2 times for the 210 denier fabrics. Summarizing the above results, it is most appropriate to combine 1000d fabric with three types of laminating films(100~200㎛ thickness) of A(0.2T) or B(0.15T) or D(0.1T) considering the air pressure resistance, the impact resistance during the fall, and the durability against damage during use.

Investigation of the effects due to a permeable double skin façade on the overall aerodynamics of a high-rise building

  • Pomaranzi, Giulia;Pasqualotto, Giada;Zassso, Alberto
    • Wind and Structures
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    • v.35 no.3
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    • pp.213-227
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    • 2022
  • The design of a building is a complex process that encompasses different fields: one of the most relevant is nowadays the energetic one, which has led to the introduction of new typologies of building envelopes. Among them, the Permeable Double Skin Façades (PDSF) are capable to reduce the solar impact and so to improve the energetic performances of the building. However, the aerodynamic characterization of a building with a PDSF is still little investigated in the current literature. The present paper proposes an experimental study to highlight the modifications induced by the outer porous façade in the aerodynamics of a building. A dedicated wind tunnel study is conducted on a rigid model of a prismatic high-rise building, where different façade configurations are tested. Specifically, the single-layer façade is compared to two PDSFs, the former realized with perforated metal and the latter with expanded metal. Outcomes of the tests allow estimating the cladding loads for all the configurations, quantifying the shielding effects ascribable to the porous layers that are translated in a significant reduction of the design pressure that could be up to 50%. Moreover, the impact of the PDSFs on the vortex shedding is investigated, suggesting the capability of the façade to suppress the generation of synchronised vortices and so mitigate the structural response of the building.