• Structural Engineering and Mechanics
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• 제70권3호
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• pp.325-337
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• 2019

In the present article, cross ply laminated composite plates are considered and a simple sinusoidal shear deformation model is tested for analyzing their flexural, stability and dynamic behaviors. The model contains only four unknown variables that are five in the first order shear deformation theory (FSDT) or other higher order models. The in-plane kinematic utilizes undetermined integral terms to quantitatively express the shear deformation influence. In the proposed theory, the conditions of zero shear stress are respected at bottom and top faces of plates without considering the shear correction coefficient. Equations of motion according to the proposed formulation are deduced by employing the virtual work principle in its dynamic version. The analytical solution is determined via double trigonometric series proposed by Navier. The stresses, displacements, natural frequencies and critical buckling forces computed using present method are compared with other published data where a good agreement between results is demonstrated.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
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• pp.258-264
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• 1999

In this study, a computer program was developed for analysis of the orthotropic curved ring sector plates. In the developing program , the thin-plate theory and multi-base coordinate system was adopted. The effect of design factors-boundary conditions, loading conditions, steel ratio, open angle, radius of curvature and relative flexural rigidity between slab and edge-beam-on the behavior of the circular ring sector plates were discussed. Also, the practical limitations was proposed to replace the problem of the orthotropic sector plate by equivalent rectangular plage.

• 한국강구조학회 논문집
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• 제26권5호
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• pp.407-418
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• 2014

본 연구에서는 HSA800 후판 강재에 적합한 용접재를 선정하고자 휨-인장실험을 수행하였다. 본 연구 수행 당시 HSA800 강재에 적용가능한 용접재로 GMAW 용접재(외국산)와 FCAW 용접재(국내산) 두 가지가 추천되어 이들을 사용하였다. 선행연구인 표준인장실험 결과를 바탕으로 맞댐용접상세와 루트간격을 주요 실험변수로하여 실물크기의 보 실험을 통해 용접부의 성능을 평가하였다. 강도 측면에서 모멘트 및 플랜지 축력 전달에 대한 조건은 두 용접재 모두 만족하였으나 연성능력 측면에서 GMAW 용접재보다는 FCAW 용접재가 일관되고 우수한 거동을 보임이 실험적으로 확인되었다. 특히 GMAW 용접재는 용접효율과 작업성의 문제로 현장에서의 상향용접이 어려운 것으로 파악되었다. 같은 완전용입용접이라도 Single bevel보다는 V-groove가 안정적인 구조거동을 보이는 것으로 나타났다. 표준인장실험결과와 휨-인장실험결과를 토대로 HSA800 후판재의 용접상세 및 용접재를 제시하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.455-460
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• 2002

In this study, a numerical analysis that can effectively predict the effect of strengthening of cracked flexural members is developed using axial deformation link elements. Concrete and interface between concrete and repair material are considered as quasi-brittle material. Reinforcing bars and reinforcing steel plates are assumed to perform as elasto-plastic materials. Unloading behavior of axial deformation link element is implemented. In the developed numerical model, a flexural member is intentionally cracked by pre-loading, then, the cracked member is repaired using extra elements, and reloaded. The results from analysis of repaired flexural members agrees well with available experiment results. Also, it was shown that the effect of strengthening and the change of failure mode with respect to the time for strengthening and thickness of repair materials. Based on the results, it was determined that the developed numerical model has a good agreement for determining failure modes and effect of strengthening in cracked flexural members. By utilizing the developed numerical analysis, the time and dimension of external strengthening in an existing cracked flexural member with predition of failure mechanism can be determined.

• Structural Engineering and Mechanics
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• 제44권6호
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• pp.735-751
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• 2012

Although being one of the most popular strengthening techniques in reinforced concrete beams, the use of steel plates bonded to the soffit raises problems of ductility. This study aims at investigating the influence of the use of perforated steel plates instead of solid steel plates on the ductility of reinforced concrete beams. A total of nine reinforced concrete beams were tested. In addition to an unplated beam, eight beams with perforated steel plates of two different thicknesses (3 mm and 6 mm) were subjected to monotonic loading. Effect of bonding the plates to the beams with anchor bolts and with additional side plates bonded to the sides of the beam with and without anchors is also investigated. The use of bolts in addition to epoxy was found to greatly contribute to the ductility and energy absorption capacity of the beams, particularly in specimens with thick plates (6 mm) and the use side plates in addition to the bottom plate was found to be ineffective in increasing the ductility of a concrete beam unless the side plates are attached to the beam with anchors bolts. The thickness of the plate was found to have little effect on the bending rigidity of the beam.

• 한국공작기계학회논문집
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• 제15권1호
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• pp.39-48
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• 2006

In this paper, polymer composites based sandwich structures like beams and plates are optimised by using parametric study. The structures are composed of fibre reinforced composites for facial material and resin concrete and PVC foam for core materials. The stacking sequences and thickness of the composites are controlled as major parameters to find out the optimal condition for machine tool components. For the plate structure of machine tool bed composites-skined sandwich structure which has several ribs are proposed to enhance bending stiffnesses in two major directions at the same time. Dynamic robustness of a machine tool structure is investigated using modal analysis. From the results optimal configuration and materials for high precesion machine tools are proposed. And the plate was made of fiber reforced composite material and PVC foam.

• Nuclear Engineering and Technology
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• 제31권2호
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• pp.214-225
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• 1999

An accurate method is presented for flexural vibrations of sectorial plates having simply supported-free and free-free radial edges, when the circular edge is either clamped or simply supported. The classical Ritz method is employed with two sets of admissible functions assumed for the transverse vibratory displacements. These sets consist of : (1) mathematically complete algebraic-trigonometric polynomials which gurantee convergence to exact frequencies as sufficient terms are retained, and (2) comer functions which account for the bending moment singularities at re-entrant comer of the radial edges having arbitrary edge conditions. Accurate (at least four significant figures) frequencies and normalized contours of the transverse vibratory displacement are presented for the spectra of corner angles [90$^{\circ}$, 180$^{\circ}$(semi-circular), 270$^{\circ}$, 300$^{\circ}$, 330$^{\circ}$, 350$^{\circ}$, 355$^{\circ}$, 360$^{\circ}$ (complete circular)] causing a re-entrant comer of the radial edges. Future solutions drawn from alternative numerical procedures and finite element techniques may be compared with these accurate results.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.399-404
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• 2002

This paper presents the results cf research on improved flexural performance cf reinforced concrete beams strengthened with bonded carbon fiber reinforced polymer plate. Recently, strengthening technique with CFRP plate were almost carried out by external bonding. But current external bonding technique cf CFRP plates may result in debonding CFRP plate. Therefore, this study proposes a strengthening method that prevents or delays debonding between CFRP plates and concrete and at the same time improves the strength. For this test, there were only 14 test beams manufactured and failure load, deflection, strains and modes cf failure have been examined Test variables included the type cf strengthening, steel ratio and strengthening length, and the effects according to each test variables were analyzed. The experimental results show that the strength and stiffness cf the beam significantly increased between 34.55 and 116.51% and the increase cf the more lead-carrying capacity than the control beams.

• 폴리머
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• 제24권4호
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• pp.459-468
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• 2000

유리 또는 아라미드 섬유를 보강재로 사용한 섬유강화 복합재료의 기계적 물성을 증진시키기 위하여 복합재료 적층판을 서로 다른 매트릭스 수지와 섬유를 선정하여 이들의 인장, 굴곡 특성을 조사하였다. 불포화 폴리에스테르와 개질된 표면의 아라미드 섬유 복합재료의 경우, 굴곡 물성의 최대값은 실란 농도가 0.5 wt%일 때 관찰되었다. 불포화 폴리에스테르 수지와 유리섬유 복합재료의 인장 물성은 vinylester계가 가장 높게 나타났으며, 굴곡물성은 isophthalic계가 가장 높은 물성을 나타내었다. 유리섬유와 불포화 폴리에스테르 수지 복합재료의 기계적 물성을 증진시키기 위해 겹침 적층판과 기계적 물성과의 상관 관계에 대해서도 연구가 병행되었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.73-74
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• 2010

콘크리트 보의 휨 보강을 위한 FRP 플레이트가 콘크리트 하면에 직접 부착될 경우 콘크리트-FRP 부착경계면에서 대부분 콘크리트 박리파괴에 의한 최종파괴가 주로 발생된다. 본 연구에서는 이들 콘크리트 박리에 의한 취성파괴를 지연시켜 부착 보강재의 수명을 보다 더 연장시키기 위하여 콘크리트와 보강재 접착경계면 사이에 얇은 두께의 중간 삽입재(알루미늄, 티타늄)를 앵커와 에폭시로 부착, 기존의 FRP 플레이트 보강방법 보다 개선된 휨 성능 보강방법에 관한 연구이다. 이를 위하여 본 연구에서는 상대적으로 가격이 저렴한 알루미늄과 재료적 성능이 우수한 티타늄을 중간삽입제로 이용, 콘크리트와 보강재 사이의 부착하였으며 이들의 활용에 따른 휨 연성 개선과 콘크리트 박리파괴 지연에 대한 효과를 측정하였다.