• Computers and Concrete
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• 제29권4호
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• pp.209-217
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• 2022

In order to analyze the static and dynamic structural characteristics of the Obermeyer gate under overflow conditions, the force characteristics and vibration characteristics of the shield plate structure are studied based on the fluid-solid coupling theory. In this paper, the effects of the flow rate, airbag pressure and overflow water level on the structural performance of shield plate of air shield dam are explored through the method of controlling variables. The results show that the maximum equivalent stress and total deformation of the shield plate decrease first and then increase with the flow velocity. In addition, they are positively correlated with the airbag pressure. What's more, we find that the maximum equivalent stress of the shield plate decreases first and then increases with the overflow water level, and the total deformation of the shield plate decreases with the overflow water level. What's more importantly, the natural frequency of the shield structure of the Obermeyer gate is concentrated at 50 Hz and 100 Hz, so there is still the possibility of resonance. Once the resonance occurs, the free edge of the shield vibrates back and forth. This work may provide a theoretical reference for the safe and stable operation of the shield of the Obermeyer gate.

• Structural Engineering and Mechanics
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• 제86권6호
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• pp.765-778
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• 2023

This study investigates the free vibration and buckling analyses of isotropic curved plate structures fixed at all ends. The Kirchhoff-Love Plate Theory (KLPT) and Finite Element Method (FEM) are employed to model the curved structure. In order to perform the finite element analysis, a four-node quadrilateral element with 5 degrees of freedom (DOF) at each node is utilized. Additionally, the drilling effect (θ_z) is considered as minimal to satisfy the DOF of the structure. Lagrange's equation of motion is used in order to obtain the first ten natural frequencies and the critical buckling values of the structure. The effects of various radii of curvatures and aspect ratio on the natural frequency and critical buckling load values for the single-bay and two-bay curved frames are investigated within this scope. A computer code based on finite element analysis is developed to perform free vibration and buckling analysis of curved plate frames. The natural frequency and critical buckling load values of the present study are compared with ANSYS R18.2 results. It has been concluded that the results of the present study are in good agreement with ANSYS results for different radii of curvatures and aspect ratio values of both single-bay and two-bay structures.

• Structural Engineering and Mechanics
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• 제73권6호
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• pp.613-620
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• 2020

The research study is focuses on a form of all-bolted joint with the external ring stiffening plate in the prefabricated steel structure. The components are bolted at site after being fabricated in the factory. Six specimens were tested under cyclic loading, and the effects of column axial compression ratio, concrete-filled column, beam flange sub plate, beam web angle cleats, and spliced column on the failure mode, hysteretic behavior and ductility of the joints were analyzed. The results shown that the proposed all-bolted joint with external ring stiffening plate performed high bearing capability, stable inflexibility degradation, high ductility and plump hysteretic curve. The primary failure modes were bucking at beam end, cracking at the variable section of the external ring stiffening plate, and finally welds fracturing between external ring stiffening plate and column wall. The bearing capability of the joints reduced with the axial compression ratio increased. The use of concrete-filled steel tube column can increase the bearing capability of joints. The existence of the beam flange sub plate, and beam web angle cleat improves the energy dissipation, ductility, bearing capacity and original rigidity of the joint, but also increase the stress concentration at the variable section of the external reinforcing ring plate. The proposed joints with spliced column also performed desirable integrity, large bearing capacity, initial stiffness and energy dissipation capacity for engineering application by reasonable design.

• 한국강구조학회 논문집
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• 제14권5호통권60호
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• pp.675-682
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• 2002

본 연구에서는 단부 철근콘크리트구조와 중앙부 철골구조로 이루어진 복합구조 보를 대상으로 내력 및 강성, 변형능력을 평가하기 위해 반복재하 실험을 행하였다. 주된 실험변수는 철근콘크리트와 철골보의 이종구조 이음부부의 응력전달을 위해 철골보에 접합되는 철근의 개수와 단부 콘크리트를 구속하여 강성을 상승시킬 목적으로 설치되는 부착판의 설치유무이다. 실험결과 모든 실험체가 방추형의 이력 거동을 나타내며 안정된 거동을 하였으며, 내력에 있어서는 부착판 설치 실험체의 경우가 기본형 실험체 보다 높게 나타났다. 또한, 강성에 있어서도 단부에 부착판을 설치한 실험체가 설치하지 않은 실험체에 비하여 보다 높게 나타났으며, 모든 실험체가 최대 내력시의 부재각이 0.03rad. 이상의 변형능력을 나타내고 있다.

• Structural Engineering and Mechanics
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• 제71권3호
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• pp.283-290
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• 2019

In global competition manufacturing companies have to produce modern, new constructions from advanced materials in order to increase competitiveness. The aim of my research was to develop a new composite cellular plate structure, which can be primarily used for structural elements of road, rail, water and air transport vehicles (e.g. vehicle bodies, ship floors). The new structure is novel and innovative, because all materials of the components of the newly developed structure are composites (laminated Carbon Fiber Reinforced Plastic (CFRP) deck plates with pultruded Glass Fiber Reinforced Plastic (GFRP) stiffeners), furthermore combines the characteristics of sandwich and cellular plate structures. The material of the structure is much more advantageous than traditional steel materials, due mainly to its low density, resulting in weight savings, causing lower fuel consumption and less environmental damage. In the study the optimal construction of a given geometry of a structural element of a road truck trailer body was defined by single- and multi-objective optimization (minimal cost and weight). During the single-objective optimization the Flexible Tolerance Optimization method, while during the multi-objective optimization the Particle Swarm Optimization method were used. Seven design constraints were considered: maximum deflection of the structure, buckling of the composite plates, buckling of the stiffeners, stress in the composite plates, stress in the stiffeners, eigenfrequency of the structure, size constraint for design variables. It was confirmed that the developed structure can be used principally as structural elements of transport vehicles and unit load devices (containers) and can be applied also in building construction.

• 한국강구조학회 논문집
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• 제16권3호통권70호
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• pp.377-385
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• 2004

본 논문에서는 강판-콘크리트 벽체구조에 부착되는 기기를 지지하기 위하여 설치되는 지지대와 벽채와의 접합 성능을 파악하기 위하여 구조실험 및 유한요소해석을 수행하였다. 구조실험은 9개의 시험체를 제작하여 파괴모드 및 최대내력을 파악하였으며 유한요소해석모델을 작성하여 이를 실험결과와 비교 검증한 후 강판두께, 스터드 볼트 간격, 지지대의 위치 및 크기 등의 영향인자가 벽체 접합부의 거동 및 내력에 미치는 변화를 살펴보았다. 해석 시험체의 하중-변형의 관계로부터 시험체의 항복내력 및 최대내력을 정의 하였으며 향후 항복선 해석을 위한 토대를 마련하였다.

• Journal of Welding and Joining
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• 제32권4호
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• pp.69-74
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• 2014

Welding distortions of large steel structures had mainly been estimated with some simplified formula obtained by lots of experience and numerical analyses for small steel structures. However, the large structures would have different characteristics of distortion with welding because of their own stiffness coming from the size itself. Therefore, in order to find some measures for preventing welding distortion of large structure, it is requite in advance to precisely analysis thermal stress and distortion during welding of the structure. Numerical analysis for larger structure has been known to take large amount of calculation time and have a poor convergency problem during the thermo-elasto-plastic calculation. In this study, a hybrid method is proposed to analysis the thermal stress and distortion of a large steel plate with the finite element analysis by incorporating with temperature distribution of the plate calculated by an analytical solution. The proposed method revealed that the thermo-mechanical analysis for welding of the large structure could be performed with a good convergence and produced precise results with much reduced time consumption.

• 한국강구조학회 논문집
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• 제22권5호
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• pp.455-463
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• 2010

본 연구는 철근콘크리트 구조와 강판 콘크리트 구조가 혼합되어 이질접합부가 있는 보형 구조물의 역학적 특성을 평가하기 위하여 수행하였다. 강판콘크리트 구조는 현재 국내와 일본, 미국 등에서 연구가 진행되고 있고, 대규모 산업설비에서 철근콘크리트 구조의 대안으로 실험연구가 수행되고 있다. 본 연구에서는 대규모 철근콘크리트 구조물에 강판 콘크리트 구조를 적용할 경우를 가정하여 보 형태의 구조물에 강판 콘크리트 구조와 철근 콘크리트 구조를 적용하여 이질접합부를 만들고, 면외하중을 파괴 시까지 가력하여 이질접합부를 가진 보형실험체의 휨 내력 및 구조특성을 평가하기 위하여 실험연구를 수행하였다.

• 소성∙가공
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• 제15권4호
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• pp.326-332
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• 2006

Sandwich structures, which are composed of a thick core between two faces, are commonly used in many engineering applications because they combine high stiffness and strength with low weight. Depending on the sheets by a rolling process, which is a more efficient and economical approach compared to other types of processes, has become an increasingly important subject of study. In this paper, we made a roll forming machine which progressive forming possible and force measurement for a roll forming of the sheet metal forming. And we designed a roll molding that arrayed of embossing size 3mm in diameter fabricate micro dimple inner structure plate. We carried out forming experiment such as array change and thickness to sts304 sheet. Ultimately, this research developed inner structure plate of high stiffness.

• Advances in nano research
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• 제13권4호
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• pp.369-378
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• 2022

Dynamic study of concrete plates under impact load is presented in this article. The main objective of this work is presenting a mathematical model for the concrete plates under the impact load. The concrete plate is reinforced by carbon nanoparticles which the effective material proprieties are obtained by mixture's rule. Impacts are assumed to occur normally over the top layer of the plate and the interaction between the impactor and the structure is simulated using a new equivalent three-degree-of-freedom (TDOF) spring-mass-damper (SMD) model. The structure is assumed viscoelastic based on Kelvin-Voigt model. Based on the classical plate theory (CPT), energy method and Hamilton's principle, the motion equations are derived. Applying DQM, the dynamic deflection and contact force of the structure are calculated numerically so that the effects of mass, velocity and height of the impactor, volume percent of nanoparticles, structural damping and geometrical parameters of structure are shown on the dynamic deflection and contact force. Results show that considering structural damping leads to lower dynamic deflection and contact force. In addition, increasing the volume percent of nanoparticles yields to decreases in the deflection.