• Steel and Composite Structures
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• 제1권3호
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• pp.313-328
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• 2001

This paper presents a three-dimensional finite element analysis methodology for a quantitative evaluation of confinement in concrete-filled box-shaped unstiffened steel columns. The confinement effects of concrete in non-circular sections can be assessed in terms of maximum average lateral pressure. A brief review of a previous method adopted for the same purpose is also presented. The previous method is based on a two-dimensional finite element analysis method involving a concrete-steel interaction model. In both the present and previous methods, average lateral pressure on concrete is computed by means of the interaction forces present at the concrete-steel interface. Subsequently, the strength enhancement of confined concrete is empirically related to the maximum average lateral pressure. The results of the former and latter methods are then compared. It is found that the results of both methods are compatible in terms of confined concrete strengths, although the interaction model yields a somewhat overestimated estimation of confinement than those of the present method when relatively high strength concrete is used. Furthermore, the confinement in rectangular-shaped sections is investigated and the reliability of previously adopted simplifications in such cases is discussed.

• Advances in aircraft and spacecraft science
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• 제2권4호
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• pp.403-425
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• 2015

This work is focused on the definition and the analysis of both complete and incomplete similitudes for the dynamic responses of thin shells. Previous numerical and experimental investigations on both structural and structural-acoustic systems motivated this further analysis, mainly centred on the incomplete (distorted) similitudes. These similitudes and the associated scaling laws are defined by using the classical modal approach (CMA) and by invoking also the Energy Distribution Approach (EDA) in order to take into account both the cinematic and energetic items. The whole procedure is named SAMSARA: Similitude and Asymptotic Models for Structural-Acoustic Research and Applications. A brief summary of the procedure is herein given and the attention is paid to the analytical models of thin stiffened and unstiffened cylindrical shells. By using the well-known smeared model, the stiffened cylinder equations are used as general framework to analyse the possibility to define exact (replicas) or distorted similitudes (avatars). Despite the extreme simplicity of the proposed models, the results are really encouraging. The final aim is to define equivalent models to be used in laboratory measurements.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권4호
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• pp.520-528
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• 2018

This paper presents the results of experimental investigation on the elastic-plastic response of steel unstiffened wedges with dead-rise $10^{\circ}$ subjected to repeated impulsive pressure loadings. Repeated drop tests were performed with both wedge thickness and drop height varied. The pressure and histories were recorded during the tests and the permanent deflections were measured after every drop. Using the recorded test result, the effects of flexibility of wedges and repetition have been investigated. From the pressure history obtained from the tests the characteristics of the impulses were identified. Numerical simulations of the tests were made using the measured pressure history and the permanent deflection predictions were compared with those of the experiments.

• 대한조선학회논문집
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• 제36권2호
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• pp.77-93
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• 1999

본 연구에서는 충격횡압력을 받는 선체 판부재의 붕괴강도 특성을 분석하고 충격하중 효과를 고려한 간이 구조설계식을 제시하고자 한다. 충격횡압력하에 판부재의 붕괴거동을 분석하기 위해 기존의 실험결과와 더불어 범용 비선형 유한요소해석 프로그램인 STARDYNE을 이용하였다. 이론적 방법으로는 먼저 강소성이론을 이용하여 정적 횡압력을 받는 판부재에 대한 붕괴강도식을 도출하였다. 또한, 변형률속도 효과를 고려하여 충격 횡압력 문제에도 적용하였다. 실제 판부재에 적용 예로써 충격횡압력을 받는 강판부재와 알루미늄합금 보강판부재에 대한 붕괴거동을 분석하였다.

• 대한조선학회논문집
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• 제33권3호
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• pp.8-21
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• 1996

본 연구의 목적은 1축압축을 받는 판 및 보강판의 최종강도추정을 위한 경험식의 도출에 있다. 이를 위해 다른 연구자에 의해 수행된 많은 실험결과를 정리 하였고, 식의 도출에 있어서 넓은 범위의 판의 치수에 대한 이들 실험결과의 유용성을 확인하였다. 또한, 필요한 치수범위에 있어서 편면보강재를 가진 보강판에 대한 압축 최종강도 실험을 추가적으로 수행하였다. 본 실험과 기존의 실험결과를 바탕으로 최소자승법에 의해 보다 더 유용한 경험식을 도출하였다.

• 대한조선학회지
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• 제27권4호
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• pp.72-82
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• 1990

해양구조물의 비보강원통 부재가 충돌로 인해 횡 충격하중을 받는 경우 비보강원통의 동적거동을 추적하고 그 결과로 발생되는 손상의 정도를 예측할 수 있는 간이 수치해석 방법을 제안하고자 한다. 이 방법에서는 국부적인 변형과 전체굽힘 변형을 별도로 자유도로 분리하여 2 자유도의 스프링-질량계로 치환하여 해석하게 된다. 변형속도를 비롯한 기타의 동적효과가 굽힘변형을 나타내는 스프링 상수값에 미치는 영향은 실험자료로부터 얻어진 수정계수를 도입하여 고려하였다. 제안된 해석방법을 사용하여 얻어진 손상정도의 값들은 실험결과와 비교적 잘 일치하고 있다.

• Earthquakes and Structures
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• 제13권5호
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• pp.473-484
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• 2017

The objective of this paper is to report on a study of the use of unstiffened thin steel plate shear walls (SPSWs) for the seismic performance improvement of reinforced concrete frames with deficient lateral rigidity. The behaviour of reinforced concrete frames during seismic activities was rehabilitated with an alternative and occupant-friendly retrofitting scheme. The study involved tests of eight 1/3 scale, one bay, two storey test specimens under cyclic quasi-static lateral loadings. The first specimen, tested in previous test program, was a reference specimen, and in seven other specimens, steel infill plates were used to replace the conventional infill brick or the concrete panels. The identification of the load-deformation characteristics, the determination of the level of improvement in the overall strength, and the elastic post-buckling stiffness were the main issues investigated during the quasi-static test program. With the introduction of the SPSWs, it was observed that the strength, stiffness and energy absorption capacities were significantly improved. It was also observed that the experimental hysteresis curves were stable, and the composite systems showed excellent energy dissipation capacities due to the formation of a diagonal tension field action along with a diagonal compression buckling of the infill plates.

• Steel and Composite Structures
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• 제2권1호
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• pp.67-84
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• 2002

Traffic decks of steel or composite motorway bridges sometimes provide the opportunity of using the composite action between an existing steel deck and a reinforced concrete plate (RC plate) in the process of rehabilitation, i.e., to increase the load-carrying capacity of the deck for concentrated traffic loads. The steel decks may be orthotropic decks or also unstiffened steel plates, which during the rehabilitation are connected with the RC plate by shear studs, such developing an improved local load distribution by the joint behaviour of the two plate elements. Investigations carried out, both experimentally and numerically, were performed in order to quantitatively assess the combined static behaviour and to qualitatively verify the usability of the structure for dynamic loading. The paper reports on the testing, the numerical simulation as well as the comparison of the results. Conclusions drawn for practical design indicated that the static behaviour of these structures may be very efficient and can also be analysed numerically. Further, the results gave evidence of a highly robust behaviour under fatigue equivalent cyclic traffic loading.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 춘계학술대회 논문집
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• pp.43-47
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• 2003

This paper presents the optimum design of cylindrical shell under external pressure loading. Two kinds of material, AI7075-T6, Ti-6AI-4V, are considered. For each material, the design variable is a thickness of the unstiffened parallel middle body shell, and the state variable, constraint, is hoop stress and the object function is total weight of the cylindrical shell. Optimization is performed by conventional FE Program, ANSYS. In addition, buckling analysis is performed for the middle body of the cylindrical shell. Finally, we calculates the payload of the cylindrical shell to keep neutral buoyancy with optimized thickness in deep-sea applications.

• Earthquakes and Structures
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• 제10권1호
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• pp.1-23
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• 2016

Steel plate shear walls (SPSWs) have been shown to be efficient lateral force-resisting systems, which are increasingly used in new and retrofit construction. These structural systems are designed with either stiffened and stocky or unstiffened and slender web plates based on disparate structural and economical considerations. Based on some limited reported studies, on the other hand, employment of low yield point (LYP) steel infill plates with extremely low yield strength, and high ductility as well as elongation properties is found to facilitate the design and improve the structural behavior and seismic performance of the SPSW systems. On this basis, this paper reports system-level investigations on the seismic response assessment of multi-story SPSW frames under the action of earthquake ground motions. The effectiveness of the strip model in representing the behaviors of SPSWs with different buckling and yielding properties is primarily verified. Subsequently, the structural and seismic performances of several code-designed and retrofitted SPSW frames with conventional and LYP steel infill plates are investigated through detailed modal and nonlinear time-history analyses. Evaluation of various seismic response parameters including drift, acceleration, base shear and moment, column axial load, and web-plate ductility demands, demonstrates the capabilities of SPSW systems in improving the seismic performance of structures and reveals various advantages of use of LYP steel material in seismic design and retrofit of SPSW systems, in particular, application of LYP steel infill plates of double thickness in seismic retrofit of conventional steel and code-designed SPSW frames.