• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.606-611
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• 2009

MiStrut is a new method to establish structural stability in designing braced excavations by making a rigid connection between top-level steel beams and soldier beams. MiStrut has a function of working as a strut as well as supporting cover plates of top-level steel beams. The structural mechanism of MiStrut is supposed to reduce flexural deformation of soldier beams, which may lead to reduced lateral earth pressures behind excavation. In this research, for verification of the performance of MiStrut, shear-wave velocities of subsurface soil before and after excavation was compared. The rigid connection of main girder beams with soldir beams reduced shear-wave velocity by 67% and lateral earth pressures by 90%, which indicates that MiStrut is effective development in reducing lateral earth pressures on braced excavation.

• Structural Engineering and Mechanics
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• 제72권1호
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• pp.61-70
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• 2019

The functionally graded materials (FGM) used in plates contain probably a porosity volume fraction which needs taking into account this aspect of imperfection in the mechanical bahavior of such structures. The present work aims to study the effect of the distribution forms of porosity on the bending of simply supported FG plate reposed on the Winkler-Pasternak foundation. A refined theory of shear deformation is developed to study the effect of the distribution shape of porosity on static behavior of FG plates. It was found that the distribution form of porosity significantly influence the mechanical behavior of FG plates, in terms of deflection, normal and shear stress. It can be concluded that the proposed theory is simple and precise for the resolution of the behavior of flexural FGM plates resting on elastic foundations while taking into account the shape of distribution of the porosity.

• Structural Engineering and Mechanics
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• 제12권1호
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• pp.1-16
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• 2001

A reliable and accurate method has been developed to predict the flexural deformation response of structural concrete members subject to service load. The method that has been developed relates the extent of concrete cracking, measured as a function of the magnitude of applied moment in a member, to the reduction in the effective moment of inertia of cracked reinforced concrete members under service load conditions. The ratio of the area of the moment diagram where the moment exceeds the cracking moment, to the total area of the moment diagram for any loading, provides the basis for the calculation of the effective moment of inertia. This ratio also represents mathematically a probability of crack occurrence. Verification of this method for the determination of the effective moment of inertia has been achieved from an experimental test program, and has included beam tests with different loading configurations, and shear wall tests subjected to a range of vertical and lateral load levels. Further verification of this method has been made with reference to the experimental investigation of other recently published work.

• 한국구조물진단유지관리공학회 논문집
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• 제21권2호
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• pp.1-12
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• 2017

본 연구에서는 대골형 파형강판 합성부재의 구성요소를 고강도 재료로 대체하고 이음방법, 전단보강방법 등 단면구성방법에 따른 단위부재의 휨거동을 분석하여 대골형 파형강판 합성부재 구조물의 장대화 및 적용범위확대를 위한 기초자료를 제시하고자 하였다. GR40과 SS590 강재를 적용한 합성구조체의 휨실험 결과, SS590 파형강판을 적용한 경우 정모멘트 하중저항성능은 약 28%가 증가되는 것으로 확인되었으나 부모멘트 저항성능은 미미한 것으로 확인되었다. 볼트의 개수를 증가시킨 파형강판 이음방법의 정모멘트 및 부모멘트 저항성능증가율은 높지 않은 것으로 확인되었다. 이는 고강도 재료에 따른 볼트의 접합 특성(볼트중심에서 연단까지의 거리, 볼트중심간 간격 등)이 거동에 영향을 미쳤기 때문인 것으로 추정된다. 전단보강재 간격별 휨실험 결과, 보강재 간격이 감소할수록 정모멘트에 대한 하중저항성능, 부모멘트에 대한 변위저항성능이 향상되는 것으로 확인되었다. 전단보강재 형상별 휨실험결과, U형 보강재 적용에 따른 정 부모멘트 저항성능 증가율은 약 2%~7% 로 낮았다. 따라서 대골형 파형강판 합성부재의 휨성능증가에는 파형강판의 강종, 전단보강재 간격, 보강철근의 특성이 주요한 영향을 미치는 것으로 판단된다.

• Steel and Composite Structures
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• 제29권1호
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• pp.91-106
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• 2018

This paper investigates the deflection of the steel-concrete composite truss beam (SCCTB) at the serviceability limit state. A precise solution for the distributed uplift force of the SCCTB, considering five different loading types, is first derived based on the differential and equilibrium equations. Furthermore, its approximate solution is proposed for practical applications. Subsequently, the shear slip effect corresponding to the shear stiffness of the stub connectors, uplift effect corresponding to the axial stiffness of the stub connectors and shear effect corresponding to the brace deformation of the steel truss are considered in the derivation of deflection. Formulae for estimating the SCCTB deflection are proposed. Moreover, based on the proposed formulae, a practical design method is developed to provide an effective and convenient tool for designers to estimate the SCCTB deflection. Flexure tests are carried out on three SCCTBs. It is observed that the SCCTB stiffness and ultimate load increase with an increase in the shear interaction factor. Finally, the reliability of the practical design method is accurately verified based on the available experimental results.

• Advances in materials Research
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• 제7권1호
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• pp.29-44
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• 2018

In this paper, a closed-form rigorous solution for interfacial shear stress in simply supported beams strengthened with bonded prestressed E-FGM plates and subjected to an arbitrarily positioned single point load, or two symmetric point loads is developed using linear elastic theory. This improved solution is intended for application to beams made of all kinds of materials bonded with a thin plate, while all existing solutions have been developed focusing on the strengthening of reinforced concrete beams, which allowed the omission of certain terms. The theoretical predictions are compared with other existing solutions. Finally, numerical results from the present analysis are presented to study the effects of various parameters of the beams on the distributions of the interfacial shear stresses. The results of this study indicated that the E-FGM plate strengthening systems are effective in enhancing flexural behavior of the strengthened RC beams.

• 콘크리트학회논문집
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• 제17권3호
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• pp.435-444
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• 2005

본 연구에서는 휨모멘트와 축력의 효과가 고려된 변환각 트러스 모델(TATM)을 이용하여 철근콘크리트 기둥의 전단거동을 예측하였다. TATM의 해석결과를 검증하기 위하여 다양한 전단경간비와 축력비를 가지는 총 9개의 철근콘크리트 기둥을 전단 실험하였다. 철근콘크리트 기둥의 곡률, 축변형 및 전단변형을 측정하기 위하여 기둥 옆면 전단위험단면을 중심으로 5개의 변위변환기(LVDT)를 설치하였다. 하중은 최대하중의 $85\%$ 이하로 떨어질 때까지 가력하였으며, 모든 실험체는 휨 철근의 항복이전에 전단파괴 되었다. 기둥의 전단강도와 강성은 축 하중이 증가할수록 증가하는 반면 전단경간비가 증가할수록 감소하였다. TATM으로부터 얻은 전단응력-전단변형률 관계와 전단응력-전단철근변형률 관계는 본 연구에서 수행된 실험결과와 잘 일치하였으며, 기존의 트러스 모델(MCFT, RA-STM, FA-STM)보다 더 우수하였다.

• Steel and Composite Structures
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• 제34권4호
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• pp.511-524
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• 2020

In this research, a simple four-variable trigonometric integral shear deformation model is proposed for the static behavior of advanced functionally graded (AFG) ceramic-metal plates supported by a two-parameter elastic foundation and subjected to a nonlinear hygro-thermo-mechanical load. The elastic properties, including both the thermal expansion and moisture coefficients of the plate, are also supposed to be varied within thickness direction by following a power law distribution in terms of volume fractions of the components of the material. The interest of the current theory is seen in its kinematics that use only four independent unknowns, while first-order plate theory and other higher-order plate theories require at least five unknowns. The "in-plane displacement field" of the proposed theory utilizes cosine functions in terms of thickness coordinates to calculate out-of-plane shear deformations. The vertical displacement includes flexural and shear components. The elastic foundation is introduced in mathematical modeling as a two-parameter Winkler-Pasternak foundation. The virtual displacement principle is applied to obtain the basic equations and a Navier solution technique is used to determine an analytical solution. The numerical results predicted by the proposed formulation are compared with results already published in the literature to demonstrate the accuracy and efficiency of the proposed theory. The influences of "moisture concentration", temperature, stiffness of foundation, shear deformation, geometric ratios and volume fraction variation on the mechanical behavior of AFG plates are examined and discussed in detail.

• 한국강구조학회 논문집
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• 제19권5호
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• pp.539-548
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• 2007

이 논문은 Pasternak지반으로 지지된 변화폭 원호형 띠기초의 휨-비틀림 자유진동에 관한 연구이다. 띠기초의 단면은 단면깊이는 일정하고, 단면폭은 1차식으로 변화하는 변화폭을 갖는 직사각형 단면으로 채택하였다. 띠기초의 지반은 Winkler지반에 전단층을 갖는 Pasternak지반으로 모형화하였다. 이러한 원호형 띠기초의 자유진동을 지배하는 상미분방정식과 경계조건을 유도하였다. 자유진동의 관성항으로는 휨관성, 회전관성 및 비틀림관성을 고려하였다. 상미분방정식을 수치해석하여 4개의 최저차 고유진동수를 산출하였다. 수치해석의 결과로 띠기초의 변수들이 고유진동수에 미치는 영향을 고찰하였다. 이 논문의 결과는 띠기초의 동적 설계에 매우 유용한 자료를 제공할 수 있을 것으로 기대된다.

• Steel and Composite Structures
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• 제49권3호
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• pp.307-323
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• 2023

In this research, the study of the thermoelastic flexural analysis of silicon carbide/Aluminum graded (FG) sandwich 2D uniform structure (plate) under harmonic sinusoidal temperature load over time is presented. The plate is modeled using a simple two dimensional integral shear deformation plate theory. The current formulation contains an integral terms whose aim is to reduce a number of variables compared to others similar solutions and therefore minimize the computation time. The transverse shear stresses vary according to parabolic distribution and vanish at the free surfaces of the structure without any use of correction factors. The external load is applied on the upper face and varying in the thickness of the plates. The structure is supposed to be composed of "three layers" and resting on nonlinear visco-Pasternak's-foundations. The governing equations of the system are deduced and solved via Hamilton's principle and general solution. The computed results are compared with those existing in the literature to validate the current formulation. The impacts of the parameters (material index, temperature exponent, geometry ratio, time, top/bottom temperature ratio, elastic foundation type, and damping coefficient) on the dynamic flexural response are studied.