• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.73-79
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• 1997

It is one of classical problems in the elastic theory to analyze contact stresses between elastic bodies. Concrete pavements under traffic wheel loads can be considered as one of these typical Problems. In the paper, Mindlin plate theory is used to consider the transverse shear effect, 8-node isoparametric plate bending element is adopted in this study, and an elastic plate resting on tensionless elastic half-space is analyzed by finite element method. The Boussineq's solution of elastic half-space is used to evaluate the flexibility of foundation. To obtain the boundary of contact area, the flexibility matrix of foundation is modified after each cycle of analysis iteratively. A Numerical example is presented by using these method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.2
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• pp.211-216
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• 2002

A steel plate-concrete composite slab with pyramidal shear connectors, named TSC composite slab, is expected to have sufficient bending strength and flexural rigidity for loads during and after construction. Fatigue problems play an important role in designing composite slab as bridge decks under traffic conditions. In this paper, a series of fatigue tests was carried out on TSC beam specimens under various loading conditions, in order to evaluate the fatigue strength of TSC composite slabs. The results are as follows : (1) the fatigue failure of TSC composite beams results from the tensile fracture of bottom steel plate and shear connector, and (2) fatigue strength of the steel plate for two million cycles can be estimated to be $1144kgf/cm^2$ from the S-N curves.

• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.3
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• pp.212-222
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• 1998

In several structural problems, the low concrete strength of compression members has the severest influence on the structural safety. However, the repairing and strengthening techniques for compression members are not established and evaluated. This study aimed to develop and evaluate the rehabilitation techniques to obtain proper structural strength of wall with low concrete strength. The specimens with low strength of concrete were retrofitted with commonly using section increase method and epoxy bonded glass fiber techniques. The tests were executed to failure under concentric and eccentric loads. In this paper, the structural behavior and failure modes were investigated to evaluate the strengthening effects of walls subjected to compression and out-of-plane bending.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.848-853
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• 2004

This is a basic experimental study elaborated on reinforced concrete beam under load, especially crack behavior, bending stiffness, deflection and strain of concrete and reinforced bar for reinforced concrete and steel fiber reinforced concrete beam in relation to fatigue loading in service ability limit states. Test parameters are concrete strength, volume. and type of steel fiber and fatigue loading in service ability limit states to be changed. In order to obtain the actual conditions of various working loads for the aforesaid reinforced concrete beam, minimum load is applied 10$\%$ of maximum design load and maximum load was applied 60$\%$, 80$\%$ and 100$\%$ respectively. Under the same condition, the test was implemented up to 1 million cycle and the result was thoroughly analyzed and reviewed.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.44-50
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• 1996

Accumulation of worn-out automobile tires creat fire and health hazards. As a possible solution to the problem of scrap-tire disposal, an experimental study was conducted to examine the potential of using tire chips as aggregate in Railroad block. This paper examines strength and toughness properties of Railroad block in which different amounts of rubber-tire particles of several sizes were used as aggregate. The Railroad block mixtures exhibited lower compressive, bending than did normal block. However, these mixtures did not demonstrate brittle failure, but rather a ductile, plastic failure, and had the ability to absorb a large amount of plastic energy under compressive loads.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.10a
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• pp.369-376
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• 2000

For the general loading condition and boundary condition, it is very difficult to obtain closed-form solutions for buckling loads and natural frequencies of thin-walled structures because its behaviour is very complex due to the coupling effect of bending and torsional behaviour. Consequently most of previous finite element formulations introduced approximate displacement fields using shape functions as Hermitian polynomials, isoparametric interpoation function, and so on. The purpose of this study is to calculate the exact displacement field of a thin-walled straight beam element with the non-symmetric cross section and present a consistent derivation of the exact dynamic stiffness matrix. An exact dynamic element stiffness matrix is established from Vlasov's coupled differential equations for a uniform beam element of non-symmetric thin-walled cross section. This numerical technique is accomplished via a generalized linear eigenvalue problem by introducing 14 displacement parameters and a system of linear algebraic equations with complex matrices. The natural frequencies are evaluated for the non-symmetric thin-walled straight beam structure, and the results are compared with available solutions in order to verify validity and accuracy of the proposed procedures.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.161-164
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• 2004

In these days, composite materials are applied to the military field like parts of air crafts, rockets, ammunitions and so on. As high pressure is loaded on the composite body, however, cracks or delamination phenomena can be occurred between layers of laminate. These cracks or delamination usually cause a deterioration of mechanical properties under the complicated loads. In this study, methods for improvement of the inter-laminar bonding strength of thick carbon/epoxy composite structures are suggested and discussed in terms of segment bending test.

• Structural Engineering and Mechanics
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• v.6 no.4
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• pp.395-409
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• 1998

This paper concerns the development and implementation of an orthotropic, stress resultant elasto-plastic finite element model for the collapse load analysis of reinforced concrete plates. The model implements yield line plasticity theory for reinforced concrete. The behaviour of the yield functions are studied, and modifications introduced to ensure a robust finite element model of cases involving bending and twisting stress resultants ($M_x$, $M_y$, $M_{xy}$). Onset of plasticity is always governed by the general yield-line-model (YLM), but in some cases a switch to the stress resultant form of the von Mises function is used to ensure the proper evolution of plastic strains. Case studies are presented, involving isotropic and orthotropic plates, to assess the behaviour of the yield line approach. The YLM function is shown to perform extremely well, in predicting both the collapse loads and failure mechanisms.

• Structural Engineering and Mechanics
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• v.39 no.2
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• pp.169-186
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• 2011

This paper is devoted to the development of the equations which describe the elastic response of a curved laminate subjected to in-plane loads and bending moments. Similar to the classic $6{\times}6$ ABD matrix constitutive relation of a flat laminate, a new $6{\times}6$ matrix constitutive relation between force resultants, moment resultants, mid-plane strains and deformed curvatures for a curved laminate is formulated. This curved lamination theory will provide the fundamental basis for the analyses of curved laminated structures. The stress predictions by the present curved lamination theory are compared to those by the curved laminate analysis that neglected the nonlinear terms in the derivation of the constitutive relation. The results show that the curved laminate analysis that neglected the nonlinear terms cannot reflect the effect of curvature and can no longer predict the stresses accurately as the curvature becomes noticeable. In this paper, a curved lamination theory that retains the nonlinear terms and, therefore, accounts for the effect of the non-flat geometry of the structure will be developed.

• Structural Engineering and Mechanics
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• v.38 no.5
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• pp.573-592
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• 2011

Comprehensive and accurate analysis of a finite foundation beam is a challenging engineering problem and an important subject in foundation design. One of the limitation of the traditional Winkler elastic foundation model is that the model neglects the effect of the interface resistance between the beam and the underneath foundation soil. By taking the beam-soil interface resistance into account, a deformation governing differential equation for a finite beam resting on the Winkler elastic foundation is developed. The coupling effect between vertical and horizontal displacements is also considered in the presented method. Using Galerkin method, semi-analytical solutions for vertical and horizontal displacements, axial force, shear force and bending moment of the beam under symmetric loads are presented. The influences of the interface resistance on the behavior of foundation beam are also investigated.