Sung-Woo Shin

Shear Strength of Reinforced High-Strength Concrete Beams with Shear Span-to-Depth Ratios between 1.5 and 2.5

Thirty high-strength concrete beams were tested under concentrated loads at midspan to determine their diagonal cracking strength and nominal shear strength. The test variables were the compressive strength of concrete, the shear span-to-depth ratio, and the vertical shear reinforcement ratio. The effects of each test variable were studied separately. Test results were compared with strengths predicted using American Concrete Institute (ACI) 318-95. It was found that for beams with shear span-to-depth ratios between 1.5 and 2.5, ACI Eq. (11-30) generally underestimates the shear strength contributed by the vertical shear reinforcement. New equations are presented for a more accurate prediction of the diagonal cracking strength and the nominal shear strength of reinforced concrete deep beams.

Confinement Effects of High-Strength Reinforced Concrete Tied Columns

An experimental study was conducted to investigate the effectiveness of transverse steel in reinforced concrete tied columns subjected to monotonically increasing axial compression. Eighteen large-scale columns() were tested. Effects of such main variables as concrete compressive strength, configurations of transverse steel, transverse reinforcement ratio, spacing of transverse steel, and spalling of concrete cover were investigated. High-strength concrete columns under concentric axial loads show extremely brittle behavior unless the columns are confined with transverse steel that can provide sufficiently high lateral confinement pressure. A consistent decrease in the deformability of the column test specimens was observed with increasing concrete strength. Test results of this study were compared with existing confinement models of modified Kent-Park, Sheikh-Uzumeri, Mander, and Saatcioglu-Razvi. The comparison indicates many existing models to predict the behavior of confined concrete overestimate or underestimate the ductility of confined concrete.

Performance of Concrete Beams Reinforced with GFRP Bars

Abstract The strengthening of reinforced concrete structures using advanced fiber reinforced polymer (FRP) composites is a very popular practice because they are light and highly resistant to corrosion. In particular, the behavior of FRP-reinforced concrete structures is a topic that attracted lot of interest in recent years. However, the application of FRP-reinforced concrete structures requires an extensive development of reliable design equations. This study focuses on the behavior of beams reinforced with different reinforcement ratios of glass fiber reinforced polymer (GFRP) bars and concrete strength. Displacement, strains, and crack width were measured to study the behavior of beams. The results of the investigation can be summarized as follows: (1) Deflections and strains of concrete beams reinforced with GFRP re-bars are generally larger than those reinforced with steel bars; (2) the strength of the concrete has a negligible effect on crack spacing and crack width; (3) and the FRP over-reinforced concrete beams in this study are safe for design in terms of deformability.

Behaviour of One-Way Concrete Slabs Reinforced with Fiber Reinforced Polymer (FRP) Bars

Over the last few decades, many researches have been conducted in order to find solution to the problem of corrosion in steel reinforced concrete. As a result, methods such as the use of stainless steel bars, epoxy coatings, and concrete additives, etc., have been tried. While effective in some situations, such remedies may still be unable to completely eliminate the problems of steel corrosion. Fiber reinforced polymer (FRP) elements are appealing as reinforcement due to some material properties such as high tensile strength, low density, and noncorrosive. However, due to the generally lower modulus of elasticity of FRP in comparison with the steel and the linear behavior of FRP, certain aspects of the structural behavior of RC members reinforced with FRP may be substantially different from similar elements reinforced with steel reinforcement. This paper presents the flexural behavior of one-way concrete slabs reinforced with FRP bars. They were simply supported and tested in the laboratory under static loading conditions to investigate their crack pattern and width, deflections, strains and mode of failure. The experimental results shows that behavior of the FRP reinforced slabs was bilinearly elastic until failure. Also, the results show that the FRP overreinforced concrete beams in this study can be safe for design in terms of deformability.

Experimental Study of Interior Slab-Column Connections Subjected to Vertical Shear and Cyclic Moment Transfer

An experimental investigation was conducted to study the seismic behavior of slabcolumn connections under vertical shear and cyclic lateral load. Test variables include gravity shear ratio (V /V0 g ) and flexural reinforcement ratio (ρ ) of slab within an effective slab width between lines that are one and one-half slab thickness ( c 3h 2 + ). The strength and ductility of the test specimens were evaluated in accordance with gravity shear ratios and slab reinforcement ratios. The shear strength of the test slabs was compared with the predictions by ACI 318-05.

A Review of Design Considerations and Representation of Sustainable Tall Building

The purpose of this paper is to introduce design considerations for the super tall building especially those related with sustainable design methodology and the topic presented in the SB11 Helsinki World Sustainable Building Conference by Hyeong-il Kim. The design of tall buildings should take into consideration of environmental impact and economic benefits from sustainable approaches to ensure low energy consumption and CO2 emissions. In the paper, author tried to identify key issues related to sustainable building technology and emphasis the role of the sustainability in tall building design. The study also provides analytical survey of the significance of adaptable use of sustainable solutions that demonstrate use of renewable energy resources, and respond to climatic conditions with energy conscious design principles including form, orientation and materiality of the buildings on the current practice.

Evaluation on Mechanical and Mixing Properties of Ultra-high Strength Concrete with fck=150MPa

Ultra-High Strength Concrete (UHSC) demands a clear presentation of its mechanical properties, as distinct from normal strength concrete, and an evaluation of the serviceability of high-rise buildings that use ultra-high strength concrete. Ultra-high strength concrete fck

Influence of Column Aspect Ratio on the Hysteretic Behavior of Slab-Column Connection

In this investigation, results of laboratory tests on four reinforced concrete flat plate interior connections with elongated rectangular column support which has been used widely in tall residential buildings are presented. The purpose of this study is to evaluate an effect of column aspect ratio (

A Study on Innovation in Technology and Design Variation for Super Tall Buildings

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Experimental Study on Hysteretic Behavior of 100 MPa Ultra High-Strength Concrete Tied Columns

The paper presented Design Variation and Technology for Super Tall Buildings, the topic presented in the 12th International Symposium of Korea Super Tall Building Forum by Hyeong-il Kim. In this paper, author review examples of technological innovations in tall building design, illustrating the interaction between architectural form and design tools. It also traces current approaches in architectural form generation and possible design solutions. It is a multidisciplinary problem and an integrated work that involves engineering, architecture, state-of-art construction technology and digital design tools. The study will show a clear linkage of generative design encouraged by technological innovations to design problems in tall building design practice, in addition to its diversely effected results by computerized design tools and construction using CAD/CAM technology.