Jae-Yeol Cho

In this paper, the compressive behavior of fiber-reinforced concrete with end-hooked steel fibers has been investigated through a uniaxial compression test in which the variables were concrete compressive strength, fiber volumetric ratio, and fiber aspect ratio (length to diameter). In order to minimize the effect of specimen size on fiber distribution, 48 cylinder specimens 150 mm in diameter and 300 mm in height were prepared and then subjected to uniaxial compression. From the test results, i

The dynamic increase factor (DIF) has been widely used to consider the rate effect in the analysis and design of concrete structures that are subject to impact loads. A variety of DIFs have been proposed by many researchers based on the results of dynamic material tests such as the split Hopkinson pressure bar (SHPB) test. These DIFs have been adopted in authoritative design guidelines and model codes such as the ACI 349–13, ACI 370R-14, fib MC2010, and UFC 3-340-02. However, previous studies di

This study includes the experimental and numerical research conducted to establish a standardized lubrication technique for a concrete split Hopkinson pressure bar (SHPB) test. Concrete SHPB tests were conducted using different quantities of high-vacuum grease, petroleum jelly, and Teflon to determine a desirable lubrication method. Subsequently, follow-up concrete SHPB tests with different specimen dimensions were performed to validate the proposed lubrication method and obtain a dynamic increa

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Dynamic increase factor (DIF) has been used to consider rate effect on compressive strength of concrete in both design and analysis of concrete structures loaded with high rate. Until now, a variety of DIFs have been suggested by various researchers, and these DIFs are adopted in design guidelines and model codes, e.g., ACI 349-13, ACI 370R-14, fib MC2010, and UFC 3-340-02. However, the DIFs includes the axial and radial inertia effects, which cause confining effect and resistance to deformation

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With the advancement of material science and infrastructure design technology, there is an increased need to reflect various loading scenarios in the design of civil infrastructures, including extreme loads such as impact and blast. However, structural behavior under extreme loads has been observed to be very different from that under static loads due to the high-rate loading condition. Therefore, extensive experimental and analytical studies have been conducted to explain the structural behavio

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Because variations associated with the strut-and-tie model (STM) in the design of pier caps could lead to over-reinforcement of steel rebars, special attention should be paid to using STMs for reasonable rebar arrangements. Here, static loading tests were conducted on three scaled-model specimens of bridge pier caps to investigate the efficient arrangement of steel reinforcement in the bridge pier cap design. To determine the effect of the loading condition on the pier cap behavior, T-type pier