• Steel and Composite Structures
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• v.4 no.4
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• pp.265-280
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• 2004

In view of the mounting cost of rehabilitating deteriorating infrastructure, further compounded by intensified environmental concerns, it is now obvious that the evolvement and application of advanced composite structural materials to complement conventional construction materials is a necessity for sustainable construction. This study seeks alternative fill materials (polymer-based) to the much-limited cement concrete used in concrete-filled steel tubular structures. Polymers have been successfully used in other industries and are known to be much lighter, possess high tensile strength, durable and resistant to aggressive environments. Findings of this study relating to elasto-plastic characteristics of polymer concrete filled steel composite beams subjected to uniform bending highlight the enormous increase in stiffness, strength and ductility of the composite beams, over the empty steel tube. Moreover, polymer based materials were noted to present a wide array of properties that could be tailored to meet specific design requirements e.g., ductility based design or strength based design. Analytical formulations for design are also considered.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.236-239
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• 2000

It is important to evaluate austenitic heat resistant stainless steel because of low weldability of austenitic heat resistant stainless steel containing high Si. This study took varestraint test for evaluation of solidification cracking sensitivity and Erichsen test for evaluation of weld metal ductility. As a result of tests, solidification crack sensitivity increased with adding $N_2$ to shielding gas, and W had detrimental effect on crack resistance, but Ce had beneficial effect on crack resistance. Under same heat input, ductility of weld metal increased with welding speed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.57-60
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• 2003

Generally, normal concrete has the disadvantages of low tensile strength, low ductility and volume instability. To improve its performance, fiber reinforced cimentitious composite(FRCC) have been development. These composites are composed of cement, sand, water, a small amount of admixtures, and an optimal amount of fiber like synthetic fiber and steel fiber. This research investigates influence of sand, hybrid fiber and fiber volume fraction, and reports the test results of mechanical properties, fracture behavior and failure pattern of the FRCC. Our experiment was observed that sand mixed FRCC has lower compressive strength and higher bending strength than no sand mixed FRCC, and more steel fiber mixed FRCC has higher compressive strength and bending strength. Hybrid FRCC of steel and polypropylene had superior properties than FRCC of polypropylene only in same fiber volume fraction.

• Computers and Concrete
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• v.3 no.4
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• pp.261-284
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• 2006

The flexural behaviour of symmetrically reinforced concrete (RC) columns cast of normal- and high-strength concrete under both monotonic and cyclic loading is studied based on an analytical procedure, which employs the actual stress-strain curves and takes into account the stress-path dependence of concrete and steel reinforcement. The analysis is particularly extended into the post-peak stage with large inelastic deformation at various applied axial load level. The effect of axial load on their complete flexural behaviour is then identified based on the results obtained. The axial load is found to have fairly large effect on the flexural behaviour of RC columns under both monotonic and cyclic loading. Such effects are discussed through examination of various aspects including the moment-curvature relationship, moment capacity, flexural ductility, variation of neutral axis depth and steel stress.

• Steel and Composite Structures
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• v.23 no.6
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• pp.669-682
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• 2017

The use of ultra high performance concrete (UHPC) in composite columns offers numerous structural benefits, and has received recent research attention. However, the information regarding the behavior of steel tube confined concrete (STCC) columns employing UHPC has been extremely limited. Thus, this paper presents an overview of previous experimental studies on circular STCC columns with taking into account various concrete strengths to point out their distinctive features. The effect of the confinement factor and the diameter to thickness ratio on both strength and ductility in circular STCC columns employing UHPC was investigated. The applicability of current design codes such as EC4, AISC, AIJ and some available analytical models for concrete confined by steel tube was also validated by the comparison of ultimate loads between the prediction and the test results of Schneider (2006) and Xiong (2012). To predict the stress-strain curves for confined UHPC in circular STCC stub columns, a simplified model was proposed and verified by the comparison with experimental stress-strain curves.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.97-100
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• 2004

Steel encased composite columns are widely used due to their excellent structural performance in terms of stiffness, strength, and ductility. However, experimental studies were usually for the columns having higher steel ratio $(3-4\%)$. There are two different design concepts for SRC columns. ACI-318 specifies the design strength of the column using the same concept of reinforced concrete columns. AISC-LRFD specifies the P-M diagram using the concept of steel column. In this paper, SRC columns have the steel ratio of $0.53\%\;and\;1.06\%$. From the test results, ACI-318 specifications showed better evaluation of SRC columns having low steel ratio. H beam and steel tube partially filled with concrete were embedded in concrete. Flexural tests showed considerably high ductility.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.825-828
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• 2004

The objective of this study is to examine mechanical properties of ductile fiber-reinforced mortar designed based on micromechanics. This mortar was produced by employing raw materials commercially available in Korea. To verify property level of this material in uniaxial tension, a series of direct tensile tests were performed with varying water cement ratio. In addition to this, flexural tests as well as compressive tests were carried out. Experiments revealed that the fiber reinforced mortar exhibited high ductility represented by strain hardening behavior in uniaxial tension. Significant enhancements of ductility, in terms of strain at peak stress and post-peak behavior, were also observed during the tests in compression and in bending.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.641-644
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• 2006

Recently, fiber cementitious composite has been researched due to its good ductility. In this paper, Ductile Fiber Reinforcement Cementitious Coposite (DFRCC) is applied as reinforcement in concrete to prove its better performance. Compare to ordinary concrete, DFRCC has higher ductility which helps control the propagation of cracking without decreasing the elastic modulus and ultimate strength. In this research, experiments of different mixture ratios have been implemented to find a suitable mixture ratio value to produce high performance DFRCC material.

• Steel and Composite Structures
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• v.25 no.1
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• pp.45-55
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• 2017

Stainless steel exhibits high ductility and strain hardening capacity in comparison with carbon steel widely used in constructions. To analyze the particular behaviour of stainless steel cover-plate joints, an experimental study was conducted. It showed large ductility and complex failure modes of the joints. A non-linear finite element model was developed to predict the main parameters influencing the behaviour of these joints. The results of this deterministic model allow us to built a meta-model by using the quadratic response surface method, in order to allow for efficient reliability analysis. This analysis is then applied to the assessment of design formulae in the currently used codes of practice. The reliability analysis has shown that the stainless steel joint design according to Eurocodes leads to much lower failure probabilities than the Eurocodes target reliability for carbon steel, which incites revising the resisting model evaluation and consequently reducing stainless steel joint costs. This approach can be used as a basis to evaluate a wide range of steel joints involving complex failure modes, particularly bearing failure.

• Advances in concrete construction
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• v.17 no.1
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• pp.1-12
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• 2024

Precast deck joints have problems due to the occurrence of additional processes at construction sites, the complexity of construction, and the lack of design and construction standards for precast deck joints. To solve these, this study proposes a new precast deck joint that uses an Ultra-High-Performance Fiber-reinforced Cement Composite (UHPFRCC) filling material containing steel fibers and a straight rebar joint. In addition, the structural performance of the proposed joint, based on various parameters, was compared to that of existing precast deck joints, and the proposed joint showed equivalent strength and ductility. Therefore, the proposed joint can solve construction site problems by replacing the existing ones. The influence of various variables is expected to provide basic data on the design and construction guidelines for the precast deck joints.