• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.285-288
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• 2008

A model for the effective moment of inertia $I_{\epsilon}$ as expressed in Branson's equation, in which reduction of the flexural rigidity of RC beams due to cracking are aptly taken into accoun,t is presented. However, KCI Code isn`t considered tension stiffening as it is in debonding of reinforcing bar. Therefore, this equation need to set up suitable to our design Code. The experimental work consisted of casting and testing a total of 6 simply supported reinforced concrete beams and a total of 4 continuos reinforced concrete beams under two point concentrated loads. Main parameters are concrete strength, coverage, bond between concrete and reinforcing bars, are known as have an effect on deflection and tension stiffening. Every test beams had the same $250{\times}350$mm rectangular section, with a simply supported clear span of 4,400 mm and a continuos clear span of 6,500 mm. Comparison of the test results with values obtained using the KCI Code equation of the effective moment of inertia showed a noticeable difference.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.138-145
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• 2020

This study was conducted to identify the structural performance of the opening in a location close to the support point in the perforated beam system of steel beams. In addition, structural performance was determined through experiments on reinforced openings using vertical and horizontal steel plates. In the steel simple beam, it was found that the opening was in a position closer to the support point, half the height of the steel beam (D/2), which was more appropriate than the height of the steel beam (D). In addition, the reinforcement effect of horizontal steel plate was greater than that of vertical steel plate reinforcement. Structural performance was improved when there was no gap between openings and steel plates.

• Fire Science and Engineering
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• v.29 no.4
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• pp.33-38
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• 2015

Loads applied on the floor are transferred through beams to columns. The beams can be designed as both end fixed or simple beams. The load bearing capacity of a beam depends on each boundary condition. However, when the load bearing capacity of a beam is evaluated in fire tests, all kinds of beams are tested using simple beam conditions. In this study, an analytical method performed using heat transfer theory and heat stress analysis based on the mechanical and thermal properties of SS-400 steel at high temperature. This method was used to clarify the differences between the two types of boundary conditions at normal and high temperature. The results show that the load bearing capacity of a both-end fixed beam at high temperature is superior to that of a simple beam. Therefore, the application of simple beam conditions in fire tests for evaluation of load bearing capacity is conservatively safe compared to fixed boundary conditions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.12-18
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• 2021

The purpose of this study is to effectively mitigate the bending displacement that occurs in the bridge due to forced vibration. We developed CTMD (Combine Tuned Mass Damper) that combines the relationship between spring and mass to control the bending behavior of simple beams. The experiment was conducted to confirm the control effect according to the change in the mass ratio of the developed CTMD. The developed CTMD is designed and manufactured so that the mass ratio can be adjusted according to the characteristics of the bridge. The maximum load of the spring applied to CTMD was fixed at 33.15 N. In order to evaluate the performance of the developed CTMD, a simple beam composed of hinges and rollers as boundary conditions was fabricated. In the experimental method, a CTMD was installed in the center of a simple beam and the deflection displacement according to the mass ratio was measured. The shaking condition was shaken at 3 Hz to induce the maximum bending behavior of the simple beam. As a result of the experiment, it was confirmed that when the optimal mass ratio was 2.1, the damping rate of the bending behavior displacement was about 71.2 %, indicating the best control effect.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.341-346
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• 2002

이 연구는 게르버 보 형식의 포스트텐션 PC 골조 구조 시스템의 실용화를 위해 골조 전체의 구조 성능 시험을 수행하며, 여기서 보-기둥 접합부 및 내민 보-단순 보 접합부의 구조 성능과 골조의 안전성을 확인한다. 시험은 400 mm$\times$800 mm 단면의 경간 3 m 보와 500 mm$\times$600 mm 단면을 갖는 높이 3 m 기둥의 실물 크기 시험체를 제작하여, 기둥에 80 톤의 축 하중을 준 상태에서 단순 보 중앙에 하중을 가력하여 기둥-보 접합부와 단순 보-내민 보 단면 축소 연결부의 구조성능을 파악한다. 시험 결과, 보 - 기둥 접합부는 예상 설계 하중 40톤 이상에서도 강 접합에 가깝게 거동하였고, 단순 보- 내민 보의 단면 축소 연결부는 경사철근의 사용으로 초기 균열 및 균열 확산에 대한 억제 효과가 있었으며, 예상 설계 전단력 40톤에서 안전하다는 것이 확인되었다.

• Magazine of the Korea Concrete Institute
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• v.10 no.4
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• pp.93-100
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• 1998

This paper presents a study on the flexural stiffness, plastic hinge length and plastic hinge rotation capacity of reinforced high performance concrete beams. 15 beams with different strength of concrete, reinforcement ratio and the pattern of loadings were tested. From the test results of reinforced normal strength concrete beams and reinforced high performance concrete beams with the concrete which has cylinder compressive strength of 700kg/${cm}^2$, slump value of 20~25cm and slump-flow value of 60~70cm. It is found that an extreme fiber concrete compressive strain of ${\varepsilon}_{cu}=0.0047$ may be used in ultimate curvature computations of reinforced high performance concrete beams. An empirical equation is proposed to estimate the effective moment of inertia. length and rotation capacity of plastic hinge of simply supported reinforced high performance concrete beams. The estimated deflections using this equation agree well with the experimental values.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.1 s.71
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• pp.55-62
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• 2006

The natural frequency of a beam plays a critical role in the dynamic analysis of beams. Especially it is a complicated and difficult task to analyse the natural frequency of a stepped beam with an irregularly varying section. The lumped mass methods, multi-degree of freedom analyses, are mainly used for the analysis of this kind of stepped beams. The accuracy of these methods are determined by the number of the partitions of elements, the number of the iterations in calculation, and the accuracy of assumed mode shapes. This study presents a method of transformation from symmetrically stepped beams to an equivalent beam and a method of the eigenvalue analysis. Appropriateness and utility of this method are demonstrated by comparing examples from other literatures and various models.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.2
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• pp.129-136
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• 2001

본 연구의 목적은 휨을 받는 철근콘크리트 단순보의 비선형 거동을 해석을 통하여 파악하기 위하여 보의 단면을 Layer로 분할하여 각 Layer에 사용된 재료의 특성을 부여하고, 작용하중에 의한 비선형 특성을 응력-변형도 모델을 통하여 반영할 수 있도록 알고리즘을 작성하는 것이다. 본 연구에서 제안한 알고리즘을 사용하면 실험을 위한 보(beam)를 제작하지 않고도 사용재료의 압축 및 인장 실험을 위한 몰드 만을 제작하여 재료에 대한 정확한 응력-변형도 모델을 작성함으로써 합성보의 거동을 수치해석을 통하여 간단하게 파악할 수 있을 것으로 기대된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2A
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• pp.155-162
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• 2009

This paper deals with the strongest beams with the solid regular polygon cross-section, whose volumes are always held constant. The differential equation of the elastic deflection curve of such beam subjected to the concentrated and trapezoidal distributed loads are derived and solved numerically. The Runge-Kutta method and shooting method are used to integrate the differential equation and to determine the unknown initial boundary condition of the given beam. In the numerical examples, the simple beams are considered as the end constraint and also, the linear, parabolic and sinusoidal tapers are considered as the shape function of cross sectional depth. As the numerical results, the configurations, i.e. section ratios, of the strongest beams are determined by reading the section ratios from the numerical data related with the static behaviors, under which static maximum behaviors become to be minimum.

• Journal of the KSME
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• v.35 no.8
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• pp.709-715
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• 1995

날로 그 중요성이 대두되고 있는 환경보존 문제에 능동적으로 대응하고 여러 계층 소비자의 안 전도, 쾌적성 등에 관련된 요구, 성능의 수준향상에 효과적으로 대처하기 위해서는 차량의 경량화 기술이 가장 먼저 선행되어야 할 과제이다. 경량화를 추구하는 방법은 최적설계 개념을 이용한 구조합리화에 의한 방법과 알루미늄, 강화 플라스틱 등 신소재 대체에 의한 방법이 병행 연구 되고 있다. 이 글에서는 구조합리화를 통한 경량화 목표를 달성하기 위해 설계 초기 단계에 활용 가능한 단순 보 모델 개발의 필요성에 관해 언급하고 실차의 도어 측면 붕괴강도(door side intrusion strength), 루프 붕괴강도 (roof crush strength) 해석을 위한 단순 보 모델 개발에 관해 소개하고자 한다.