• Journal of the Korean Wood Science and Technology
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• v.43 no.1
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• pp.86-95
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• 2015

This study was performed to study physical and mechanical properties of hybrid cross laminated timber (HCLT) with plywood as core layer in order to improve its mechanical properties for wooden housing. MOE, MOR, and dimensional stability of the HCLT were determined, depending on plywood composition and lamination direction. MOR value of the HCLT was improved as much as that of the glued laminated timber, which was 59.6% stronger than that of the cross laminated timber (CLT) control group. All MOE values of the HCLT were similar to glued laminated timber structure control group regardless of plywood composition and lamination directions. The dimensional stability of the HCLT was better than those of the glued laminated timber and CLT control group, owing to the use of plywood in the core.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.6
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• pp.1075-1088
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• 1992

This paper presents techniques used to model a two arm experimental robot. Both arms are compliant and the robot operates in a vertical plane and is therefore influenced by gravity. The robot is being built to study different control strategies for robots containing compliant members. The system is built with extremely flexible members. This limits the required bandwidth of the control electronics, and mimics the flexible motions that are observed for stiffer faster robots. The objective of this paper is to develop a reduced order model of the robot system and to experimentally validate the model. Validation requires that the model includes gravitational effects. Therefore, an assumed modes model is developed which facilitates modeling of gravitational effects. In order to select the order and mode shapes for the model, an analytical solution is derived for a linearized continuous model. This is compared to the assumed modes model to determine the number of mode shapes needed to model the system. The final model, which includes shortening effects, correlates very well with experimental results.

• Journal of the Korea Concrete Institute
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• v.25 no.4
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• pp.381-388
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• 2013

This study presents that effect of anchor plate on concrete breakout strength was evaluated. The addition of the anchor plate is to improve the concrete breakout capacity for a single anchor system in a thin-walled concrete panel (Insulated concrete sandwich wall panel). In this study, an elasticity-based simplified model was developed and used to predict effect on the anchor plate. Flexural stresses of the plate with respect to the concrete breakout strength obtained from CCD (Capacity Concrete Design) approach were compared with the test results. Through the test results, while the concrete breakout strength was improved due to increment of the width and thickness of the anchor plate, improvement of the strength was steadily declined. In addition, the It was observed that the analytical and experimental flexure of the anchor plate was comparatively in good agreement using the simplified elastic analysis model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.81-92
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• 2013

The ultimate flexural strength of HSB I-girders, considering the effect of local bucking, was investigated through a series of nonlinear finite element analysis. The girders were selected such that the inelastic local flange buckling or the plastic yielding of compression flanges governs the flexural strength. Both homogeneous sections fabricated from HSB600 or HSB800 steel and hybrid sections with HSB800 flanges and SM570-TMC web were considered. In the FE analysis, the flanges and web were modeled using thin shell elements and initial imperfections and residual stresses were imposed on the FE model. An elasto-plastic strain hardening material was used for steels. After establishing the validity of present FE analysis by comparing FE results with test results published in the literature, the effects of initial imperfection and residual stress on the inelastic flange local buckling behavior were assessed. The ultimate flexural strengths of 60 I-girders with various compression flange slenderness were obtained by FE analysis and compared with those calculated from the KHBDC, AASHTO LRFD and Eurocode 3 provisions. Based on the comparison, the applicability of design equations in these specifications for the flexural strength of I-girder considering flange local buckling was evaluated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.3207-3215
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• 2012

In this paper, we study the bending and free vibration analysis of nano plate, using a nonlocal elasticity theory of Eringen with a third-order shear deformation theory. This theory has ability to capture the both small scale effects and quadratic variation of shear strain and consequently shear stress through the plate thickness. Analytical solutions of bending and vibration of a laminated composite nano plate are presented using this theory to illustrate the effect of nonlocal theory on deflection of the nano plates. The relations between nonlocal third-order and local theories are discussed by numerical results. Further, effects of (i) nonlocal parameters, (ii) laminate schemes, (iii) directions of the fiber angle and (iv) number of layers on nondimensional deflections are investigated. In order to validate the present solutions, the reference solutions are used and discussed. The results of anisotropic nano plates using the nonlocal theory may be the benchmark test for the bending analysis.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.323-326
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• 2009

콘크리트의 보강재로 높은 인장 강도와 비부식성, 비자기성, 비전기성 등의 장점을 갖는 FRP의 사용에 대한 연구가 활발히 진행되고 있다. 하지만 FRP가 갖는 낮은 탄성계수와 취성적 성질로 인해 기존 설계방법을 적용하기에는 문제가 있다. 본 연구에서는 보강비 변화에 따른 AFRP 보강 콘크리트 보의 구조 실험을 수행하여 FRP 보강근을 사용한 콘크리트 부재의 휨 성능 연구에 대한 기초적 자료를 제공하고자 하였다. 각 실험체의 결과 데이터를 비교 분석한 결과 균형보강비를 기준으로 저보강 실험체는 FRP의 파단에 의해 급격한 파괴양상을 보인 반면에, 과보강 실험체는 콘크리트가 압괴하는 파괴 징후를 보이며 파괴에 도달하였다. FRP 보강근을 사용한 보 부재의 설계에 균형보강 이상의 설계가 요구되며, 과보강의 경우 고강도 콘크리트의 사용이 요구되는 것으로 분석되었다.

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.631-633
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• 2012

본 논문은 구조용 후판 강재로 절곡되었을 때, 절곡부재의 구조연성 변화에 대한 해석 방안과 이에 따른 해석적 평가 사례를 제시하고 있다. 절곡 방법에 의한 제작과정에서 재료는 변형경화 현상이 발생한다. 이로 인해 구조연성 저하가 불가피하기 때문에 절곡부재의 휨연성 검토가 필요하다. 해석 방안은 유한요소해석 프로그램인 ABAQUS를 이용하였다. Lanczos 알고리즘을 적용한 고유치해석과 재료 비탄성-기하비선형을 고려한 비선형 해석을 하였다. 비선형해석 절곡에 의한 재료특성을 고려하였다. 극한 하중과 파괴모드를 평가하기 위해 Newton-Raphson method, modified Riks method를 적용한 단계별 하중재하 해석을 실시하였다. 본 연구를 통해 휨연성을 평가하는데 활용 될 것으로 판단된다.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.2
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• pp.11-15
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• 2009

This paper is concerned with the elastic buckling of thin-walled arches that are subjected to uniform bending. Nonlinear strain-displacement relations with the initial curvature are substituted into the second variation of the total potential energy to obtain the energy equation including initial curvature effects. The approximation for initial curvature effects that the bending normal strain distribution is linear across the cross section is applied consistently in the derivation process. The closed form solution is obtained for flexural-torsional buckling of arches under uniform bending and, it is compared with the previous theoretical results.

• Journal of the Korean Wood Science and Technology
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• v.29 no.2
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• pp.118-125
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• 2001

In this study, it was examined the characteristics of bending property of red pine(Pinus densiflora S, et Z.) related to slope of grain. At first, we have investigated the characteristics of wood species for bending property. At second, it was examined the relationships between grain angle and its related bending property. Specimens were made following to grain angle $0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, $90^{\circ}$, respectively. Dimension of wood materials was $10mm(T){\times}20mm(R){\times}350mm(L)$. Microwave irradiation time for bending process was 30, 60, 90, 120 seconds. The result of this study were as follows ; 1. Grain angle of wood was closely related to Young's modulus on bending process. In the process of bending with various grain angle, wood bending was easily proceed on the high grain angle range. 2. However, the strength of bent wood was very weak when the grain angle was high. Therefore, it was considered suitable grain angle for bending was existed. 3. The characteristics of wood properties for wood bending were very different among wood species.

• Journal of the Society of Disaster Information
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• v.10 no.1
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• pp.61-70
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• 2014

Synthetic fiber reinforced concrete is applicable to many applications for construction material. In general, synthetic fibers have low tensile strength and elastic modulus, but they have many advantages such as high crack resistance, impact resistance, chemical resistance, flexural behavior and corrosion free in fiber reinforced concrete. Recently, fiber reinforced concrete with macro synthetic fibers has been used to improve performance of structures in tunnel shotcrete, precast segmental lining and bridge slab and precast concrete structures. This study investigated the influence of bundled type polyamide fiber reinforced concrete on the flexural behavior in accordance with ASTM C 1609 and KS F 2566 standards.