• Structural Engineering and Mechanics
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• 제6권4호
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• pp.377-394
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• 1998

Slit shear walls an reinforced concrete shear wall structures with purposely built-in vertical slits. If the slits are inserted with visco-elastic damping materials, the shear walls will become viscoelastic sandwich beams. When adequately designed, this kind of structures can be quite effective in resisting earthquake loads. Herein, a simple analysis method is developed for the evaluation of the stochastic responses of visco-elastic slit shear walls. In the proposed method, the stiffness and mass matrices are derived by using Rayleigh-Ritz method, and the responses of the structures are calculated by means of complex modal analysis. Apart from slit shear walls, this analysis method is also applicable to coupled shear walls and cantilevered sandwich beams. Numerical examples are presented and the results clearly show that the seismic responses of shear wall structures can be substantially reduced by incorporating vertical slits into the walls and inserting visco-elastic damping materials into the slits.

• Structural Engineering and Mechanics
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• 제44권4호
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• pp.465-485
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• 2012

Different mathematical models are proposed and their analytical solutions derived for the analysis of linear elastic Reissner's multilayer beams. The models take into account different combinations of contact plane conditions, different material properties of individual layers, different transverse shear deformations of each layer, and different boundary conditions of the layers. The analytical studies are carried out to evaluate the influence of different contact conditions on the static and kinematic quantities. A considerable difference of the results between the models is obtained.

• Steel and Composite Structures
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• 제1권2호
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• pp.213-230
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• 2001

This paper presents a simplified approach for the design of semi-continuous composite beams in braced frames, where specific attention is given to the effect of joint rotational stiffness. A simple composite beam model is proposed incorporating the effects of semi-rigid end connections and the nonprismatic properties of a 'cracked' steel-concrete beam. This beam model is extended to a sub-frame in which the restraining effects from the adjoining members are considered. Parametric studies are performed on several sub-frame models and the results are used to show that it is possible to correlate the amount of moment redistribution of semi-continuous beam within the sub-frame using an equivalent stiffness of the connection. Deflection equations are derived for semi-continuous composite beams subjected to various loading and parametric studies on beam vibrations are conducted. The proposed method may be applied using a simple computer or spreadsheet program.

• Coupled systems mechanics
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• 제2권3호
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• pp.215-230
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• 2013

This paper investigates the pull-in instability of functionally graded poly-SiGe micro-beams under the combined electrostatic and intermolecular forces and temperature change. The exponential distribution model and Voigt model are used to analyze the functionally graded materials (FGMs). Principle of virtual work is used to derive the nonlinear governing differential equation which is then solved using differential quadrature method (DQM). A parametric study is conducted to show the significant effects of material composition, geometric nonlinearity, temperature change and intermolecular Casimir force.

• 콘크리트학회논문집
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• 제20권6호
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• pp.755-763
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• 2008

본 연구에서는 강섬유보강 콘크리트와 L형강을 사용한 합성 복근보의 구조성능을 평가하고자 실험 연구를 수행하였다. 총 6개의 강섬유보강 합성 복근보 실험체를 제작하였으며, 모든 실험체는 혼입률 1%의 강섬유 보강이 이루어졌다. 실험체의 주요 변수는 전단보강상세와 전단경간비이며, 실험에서 구한 강도특성을 대상으로 설계강도 산정식의 적용성을 분석하였다. 또한 실험체의 강성, 연성능력 및 에너지소산능력 등의 구조성능을 평가하였다. 그 결과에 의하면 합성보의 휨 및 전단강도 산정식은 양호한 수준으로 실험체의 강도특성을 예측할 수 있었다. 한편 실험체에 적용한 전단보강상세에 따라 최대강도, 연성능력, 에너지흡수능력이 다르게 나타나고 있으며, 트러스 형태의 대각부재에 의한 전단보강상세가 가장 우수한 구조성능을 보여 주었다.

• Structural Engineering and Mechanics
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• 제39권3호
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• pp.427-447
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• 2011

The progressive collapse phenomenon is generally regarded as dynamic. Due to the impracticality of nonlinear dynamic computations for practitioners, an interest arises for the development of equivalent static pushover procedures. The present paper proposes a methodology to identify such a procedure for sudden column removals, using energetic evaluations to determine the pushover loads to apply. In a dynamic context, equality between the cumulated external and internal works indicates a vanishing kinetic energy. If such a state is reached, the structure is sometimes assumed able to withstand the column removal. Approximations of these works can be estimated using a static computation, leading to an estimate of the displacements at the zero kinetic energy configuration. In comparison with other available procedures based on such criteria, the present contribution identifies loading patterns to associate with the zero-kinetic energy criterion to avoid a single-degree-of-freedom idealisation. A parametric study over a family of regular steel structures of varying sizes uses non-linear dynamic computations to assess the proposed pushover loading pattern for the cases of central and lateral ground floor column failure. The identified quasi-static loading schemes are shown to allow detecting nearly all dynamically detected plastic hinges, so that the various beams are provided with sufficient resistance during the design process. A proper accuracy is obtained for the plastic rotations of the most plastified hinges almost independently of the design parameters (loads, geometry, robustness), indicating that the methodology could be extended to provide estimates of the required ductility for the beams, columns, and beam-column connections.

• 한국전산구조공학회논문집
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• 제24권2호
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• pp.149-156
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• 2011

본 논문에서는 생브낭의 원리를 이용하여 보/판/쉘 등의 구조물에서 응력분포를 후처리함으로써 개선할 수 있는 방법을 개발하였다. 생브낭의 원리에 따르면, 주어진 탄성문제에 대해서 실제의 응력분포에 상관없이 합응력들로 문제를 기술할 수 있다. 현재까지 알려진 바에 따르면 유일하게 점근적으로 타당한 이론들은 Euler-Bernoulli(E-B) 보이론과 Kirchhoff-Love(K-L) 판이론 등이 있다. 많은 공학적 문제들이 이 두 이론들에 기초하여 해석되어 왔음은 주지의 사실이다. 하지만, 현대의 공학 문제들은 보다 정확한 해석기법을 요구한다. 본 연구에서는 자유도가 상대적으로 많은 고차이론 등을 사용하지 않고, 고전적인 E-B 또는 K-L 해석결과를 합응력 등가의 원리를 이용하여 후처리함으로써 변위 및 응력분포를 정확하게 예측할 수 있는 방법을 개발하였고, 이방성 보 수치예제를 통해 제안된 방법론을 탄성해석법과 비교 검증하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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• pp.607-612
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• 1998

In this study, the behavior of R/C beam strengthened with carbon fiber laminate(C.F.L) is analyzed from the test results. Test parameters are the width, the thickness and the length of C.F.L. and method of construction. The failure mode and ultimate load are analyzed from these measured data. Test results shows that the peak moment of specimens strengthened with C.F.L is increased to 1.43~1.90 times of that of non-rehabilitation specimen. The wider lap width, larger amount of rehabilitation materials, the larger strength is obtained.

• 전자공학회논문지A
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• 제33A권3호
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• pp.152-162
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• 1996

Diffraction gratings were designed to generate multiple beams for the real-time optical interconnection in free-space using a liquid crsytal television. Multi-level phase gratings consisted of stepped phase value, 0 to 2$\pi$, and generate a 5$\times$5 spot array, and V-shaped spot patterns which have a maximum diffraction efficiency of 78.84%. Simulated annealing technique was used to determine phase states of each pixel having uniform intensity and high diffraction efficiency. Through the optical interconnection experiments, we compared the diffraction characteristics of beam paterns obtained by binary-level, four-level, and eight-level phase gratings.

• Architectural research
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• 제24권2호
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• pp.53-61
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• 2022

Irregularities in the structure are crucial factors in screening structural vulnerability under extreme loadings. Numerical analyses were carried out considering wind and seismic loadings for four structures with discrete irregularity: continuous and discontinuous beams with varied story levels, and L-shaped irregular buildings. Structural responses such as maximum displacements, bending moments, axial forces, torsions, and story drifts are evaluated as per the criteria and limits defined by ACI 318. The outcomes indicate that the frame system with beam discontinuity on the upper half of the height exhibits the best structural performance. The results also indicate that the asymmetrical design of the L-shaped model makes it more susceptible to damage when subjected to strong lateral loading conditions.