• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.477-478
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• 2009

The objective of this study is to increase the insight of the mechanical behaviour of high-strength concrete prepared with fiber reinforcement after exposure to elevated temperatures. In particular, the result of the effects of contents of polypropylene fiber and level of preload on the residual compressive strength, load bearing and stress-strain curve of concrete are discussed

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.433-439
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• 2000

Reinforced concrete beams show increased ductile behavior when the compressive concrete is confined with transverse steel. In the inelastic range, the most variations of ductile behaviour are defined the equivalent length of the plastic hinge and the plastic hinge rotation. In an investigation to study the influence of such confinement, sixteen reinforced concrete beams were tested in flexure and the deflections noted at all stages of loading. For all the beams tested, the plastic hinge rotation have been computed and the effect of confinement on the same examined. The conclusions are summarized as follows: The equivalent lengths of the plastic hinge are ranged within the effective depth comparatively. The ability of the plastic hinge rotation of the reinforced concrete beams confined with transverse steel are enlarged when transverse reinforcement content are increased, but the spaces are more important as the shear force are largely increased.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.552-557
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• 1997

In this study, a quantitative analysis technique for the damage process of reinforced concrete beams under repeated shear loading is proposed, which can express the progressively increasing strain and stiffness reduction. The analysis technique is mainly based on the modified compression field theory and scalar damage concept. which describe the strain and stress configuration in the shear zone by considering the 2-dimensional effect, and express the degradation of principal compressive strut by cyclic strain increment, secant modulus decrement, and modifying the parabolic stress strain relationship. The analysis of the response of RC beams under repeated shear-flexure loading has been carried out and compared with the experimental results. The present theory may efficiently be used to evaluate the deflection and strain accumulation under repeated loadings.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.527-532
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• 1997

Design strength of structural members could be determined by applying a strength reduction factor to nominal strength. At the beginning point of the transition region for the strength reduction factor, P=0.1$\sigma$$_{ck}A_g$, only sectional area and concrete strength are adopted as the variables of P=0.1$\sigma$$_{ck}A_g$. Therefore, P=0.1$\sigma$$_{ck}A_g$ is the empirically adopted which does not consider steel ratio, steel yielding stress, and steel arrangement. So, this research was perpormed the computer program for the analysis of axial force-moment-curvature relationship of reinforced concrete columns by sectional behaviour nonlinear analysis using a concrete compressive stress-strain curve, in order to investigate the ductility of reinforced concrete columns. As a result, ductility indicies of axial force, P=0.1$\sigma$$_{ck}A_g$, represented the lack of consistency of the indicies value for the various sections.

• Structural Engineering and Mechanics
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• v.9 no.6
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• pp.589-600
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• 2000

This paper attempts to provide a theoretical basis for the design of high-strength concrete columns in terms of the spacing of lateral reinforcement. In order to achieve this, important concepts had to be addressed such as the choice of a measure of ductile behaviour and a realistic high-strength concrete stress-strain model, as well as limiting factors such as longitudinal steel buckling and lateral steel fracture. A design method incorporating above factors are suggested in the paper. It is shown that both buckling of longitudinal steel and hoop fracture will not demand a reduction in spacing of lateral ties with increase in compressive strength of concrete.

• International Journal of Automotive Technology
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• v.6 no.3
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• pp.229-234
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• 2005

The dynamic crack growth in ductile steel is investigated by means of the impact loaded 3 point bending (3PB) specimens. Results from experiments and numerical simulations are compared to each other. A modified 3PB specimen designed with the reduced width at its ends has been developed in order to avoid the initial compressive loading of the crack tip and also to avoid the uncertain boundary conditions at the impact heads. Numerical simulations of the experiments are made by using a finite element method (FEM) code, ABAQUS. The high speed photography is used to obtain the crack growth and the data of the crack tip opening displacement (CTOD). The direct measurements of the relative rotations of two specimen halves are made by using the Moire interference pattern.

• Steel and Composite Structures
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• v.24 no.4
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• pp.383-390
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• 2017

This paper highlights the experimental and numerical investigations performed on a tubular T-joint fabricated from circular hollow sections under axial compressive loads applied at the brace. Tests were performed on a reference joint and the joint wrapped with Carbon Fiber Reinforced Polymer (CFRP). The Nitowrap EP carbon fiber with Nitowrap 410 resin serve as a composite material is used for wrapping the T-joint. Schematic diagram of the fabricated tubular joint for the experimental test setup, along with the experimental and numerical results are presented. After performing these experiments, it has been demonstrated that the joint wrapped with CFRP has a better strength and lesser deflection than a reference joint. Finite element analysis carried out in Ansys reveals that the results were in good correlation with the experimental values.

• Steel and Composite Structures
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• v.4 no.2
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• pp.95-112
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• 2004

A series of tests was performed to consider the behaviour of short composite columns under axial compressive loading, covering a range of S275 and S355 grade steel square hollow section filled with normal and high strength concrete. The interaction between the steel and the concrete component is considered and the results show that concrete shrinkage has an effect on the axial strength of the column. Comparisons between Eurocode 4, ACI-318 and the Australian Standards with the findings of this research were made. Result showed the equation used by the ACI-318 and the proposed Australian Standards gave better predication for the axial capacity of concrete filled SHS columns than the Eurocode 4.

• Structural Engineering and Mechanics
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• v.31 no.4
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• pp.423-437
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• 2009

In order to perform a step-by-step force-displacement response analysis or dynamic time-history analysis of large buildings with masonry infilled R/C frames, a continuous force-deformation model based on an equivalent strut approach is proposed for masonry infill panels containing openings. The model, which is applicable for degrading elements, can be implemented to replicate a wide range of monotonic force-displacement behaviour, resulting from different design and geometry, by varying the control parameters of the model. The control parameters of the proposed continuous model are determined using experimental data. The experimental program includes fifteen 1/3-scale, single-story, single-bay reinforced concrete frame specimens subjected to lateral cyclic loading. The parameters investigated include the shape, the size, the location of the opening and the infill compressive strength. The actual properties of the infill and henceforth the characteristics needed for the diagonal strut model are based on the assessment of its lateral resistance by the subtraction of the response of the bare frame from the response of the infilled frame.

• Tunnel and Underground Space
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• v.6 no.1
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• pp.1-9
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• 1996

Pocheon granite specimens were thermally treated with cycles of predetermined temperatures ranging 2$0^{\circ}C$ to $600^{\circ}C$. Characterization of thermally-induced microcracks were carried out using optical microscopy and their effect on the various physical & mechanical properties were studied. Generally. uniaxial compressive strength, Young's modulus, Poisson's ratio, elastic wave velocity and specific gravity were found to decrease with increasing temperature. From 30$0^{\circ}C$ upwards, negative lateral strains were observed, which resulted in negative Poisson's ratio. Dynamic Young's modulus and Poisson's ratio were found to be generally most sensitive indicators to thermal cracking.