• Geomechanics and Engineering
• /
• 제28권2호
• /
• pp.197-207
• /
• 2022

The seismic holding behaviors of plate anchor embedded into submerged coarse-grained soils were investigated considering different anchor inclinations. The limit equilibrium method and the Pseudo-Dynamic Approach (PDA) were employed to calculate the inertia force of the soils within the failure rupture. In addition, assuming the permeability of coarse-grained soils was sufficiently large, the coefficient of hydrodynamic force applied on the inclined plate anchor is obtained through adopting the exact potential flow theory. Therefore, the seismic holding resistance was calculated as the combination of the inertia force and the hydrodynamic force within the failure rupture. The failure rupture can be developed due to the uplift loads, which was assumed to be an arc of a circle perpendicular to the anchor and inclines at (π/4 - φ/2). Then, the derived analytical solutions were evaluated by comparing the static breakout factor N_γ to the published experimental and analytical results. The influences of soil and wave properties on the plate anchor holding behavior are reported. Finally, the dynamic anchor holding coefficients N_γd, were reported to illustrate the anchor holding behaviors. Results show that the soil accelerations in x and z directions were both nonlinear. The amplifications of soil accelerations were more severe at lower normalized frequencies (ωH/V) compared to higher normalized frequencies. The coefficient of hydrodynamic force, C, of the plate anchor was found to be almost constant with anchor inclinations. Finally, the seismic anchor holding coefficient oscillated with the oscillation of the inertia force on the plate anchor.

• Journal of Biosystems Engineering
• /
• 제17권2호
• /
• pp.156-170
• /
• 1992

The force-deformation relationship gives the basic physical properties of the fruits such as the bioyield point, the rupture point, and the deformations at the bioyield point and the rupture point. These informations are very important to study the stress-strain relationships of the fruits. This study was conducted to analyze those physical properties according to the sampling position of the fruits, and to determine the bioyield point, the rupture point, and the deformations at the bioyield point and the rupture point of the fruits for two different storage conditions(low temperature and normal temperature) and the storage period, and to investigate the effect of loading rate on those physical properties, the hysteresis on the loading-unloading condition and the degree of elasticity of the fruits. The results of the study were as follows : 1. The physical properties(BS, US, BD, and RD) of the test specimen selected from the different sampling positions were quite different. The values of the physical properties were shown smallest ones at the cheek of the fruits, and the statistical test results of the physical properties between the cheek from the other two positions of the fruits showed that there were significant difference at the 1 % level between them. 2. The effect of loading rate on the physical properties of the fruits was relatively large, all the considered physical propertis of the fruits increased with the loading rate, but the hysteresis loss decreased with it. 3. The physical properties of the fruits according to the storage conditions and period showed different, and the bioyield deformation and the rupture deformation of the fruits increased with the storage period, but the bioyield strength and the ultimate strength of the fruits decreased with it. The effect of the storage conditions on the those physical properties showed that the normal temperature storage condition was a little higher than the low temperature storage condition. 4. As a whole, it was shown that the bioyield strength and the ultimate strength of the pear decreased a little faster than those of the apple, and the bioyield deformation and rupture deformation of the pear increased a little faster than those of apple at the two storage conditions.

• Journal of Biosystems Engineering
• /
• 제40권3호
• /
• pp.201-211
• /
• 2015

Purpose: Designing equipment for processing, sorting, and other post-harvest operations of agricultural products requires information about their physical properties. This study was conducted to investigate some of the mechanical and physical properties of Moringa oleifera L. pods and seeds. Methods: Properties such as the length, width, thickness, bulk density, porosity, mass, static coefficient of friction, and angle of repose were determined as a function of moisture content. Statistical data and force-deformation curves obtained at each loading orientation and moisture level were analyzed for bioyield point, bioyield strength, yield force, rupture point, and rupture strength using a testrometric machine. Result: The basic dimensions (length, width, and thickness) of moringa pods and seeds were found to increase linearly from 311.15 to 371.45 mm, 22.79 to 31.22 mm, and 22.24 to 29.88 mm, respectively, in the moisture range of 12 to 49.5% d.b. The coefficient of friction for both pods and seeds increased linearly with an increase in moisture content on all the surfaces used. The highest value was recorded on mild steel, with 0.581 for pods and 0.3533 for seeds, and the lowest on glass for pods, with a value of 0.501, and of 0.2933 for seeds on galvanized steel. The bioyield and rupture forces, bioyield and rupture energies, and deformation of the pods decreased with an increase in moisture content to a minimum value, then increased with further decrease within the moisture content range, while the yield force increased to a maximum value and then decreased as the moisture content increased. Conclusion: These results will help to determine the most suitable conditions for processing, transporting, and storing moringa pods, and to provide relevant data useful in designing handling and processing equipment for the crop.

• Journal of Mechanical Science and Technology
• /
• 제14권2호
• /
• pp.215-225
• /
• 2000

The structural integrity of the fuel test loop (FTL) in a Korean experimental reactor is evaluated when the FTL, submerged in a water environment, is subjected to a postulated pipe rupture. The analyses are performed under static and dynamic conditions, imposing the thrust force history at each postulated pipe rupture section. Through analysis the following results are found: l) A double ended guillotine can not be expected based on the toughness of the material, 2) the structural integrity of the chimney surrounding the FTL would not impede the structural integrity by the pipe whip. All analyses are performed by finite element methods.

• International Journal of Concrete Structures and Materials
• /
• 제10권3호
• /
• pp.373-381
• /
• 2016

As part of this study, has been developed a numerical method which allows to establish abacuses connecting the normal force with bending moment for a circular section and therefore to predict the rupture of this type of section. This may be for reinforced concrete (traditional steel) or concrete reinforced with steel fibers. The numerical simulation was performed in nonlinear elasticity up to exhaustion of the bearing capacity of the section. The rupture modes considered occur by plasticization of the steel or rupture of the concrete (under compressive stresses or tensile stresses). Regarding the fiber-reinforced concrete, the rupture occurs, usually, by tearing of the fibers. The behavior laws of the different materials (concrete and steel) correspond to the real behavior. The influence of several parameters was investigated, namely; diameter of the section, concrete strength, type of steel, percentage of reinforcement and contribution of concrete in tension between two successive cracks of bending. A comparison was made with the behavior of a section considering the conventional diagrams of materials; provided by the BAEL rules. A second comparative study was performed for fibers reinforced section.

• 비파괴검사학회지
• /
• 제20권5호
• /
• pp.438-444
• /
• 2000

WC-Co 초경합금의 항자력과 자기포화도를 평가하여 합금조직과 이에 따른 기계적 성질의 예측에 관해 연구하였다. WC 입경이 다르고 탄소함량 및 소결온도가 다른 WC-8%-Co 초경합금을 분말 야금법에 의해 제조하였다. 항자력과 자기포화도와 같은 WC-Co 합금의 자기적 특성은 합금조성 및 조직에 크게 의존하였다. 미소한 합금탄소량의 변화와 WC 입도의 차이에 의해서도 WC-Co 합금의 자기적 특성과 경도 및 항절력이 크게 변화하였다. WC 입도가 미세할수록 소결합금의 항자력과 경도는 증가하였고, 항자력은 경도의 증가와 비례하였다. WC-8%Co 합금의 화학 양론적 조성 아래로 카본함량이 감소하면 자기포화도와 항절력이 떨어지고 $\eta$상의 체적률도 꾸준히 증가하였다. WC-Co 합금에 있어서 자기포화도는 항자력과 반비례하였다.

• 대한정형외과스포츠의학회지
• /
• 제10권2호
• /
• pp.117-120
• /
• 2011

심수지 굴건의 견열성 파열은 상대적으로 드문 손상으로 심수지 굴건의 파열은 주로 심수지 굴건이 수축된 상태에서 순간적으로 일어나는 원위지절의 신전에 의해 일어나거나 중립위의 수지 말단에 강한 신전력이 작용하여 과신전되어 발생한다. 본 증례는 22세 남자 전투 경찰대원으로 방패를 쥔 상태에서 진압훈련 후 2일째 심수지 굴건의 파열이 발생한 드문 경우로 문헌 고찰과 함께 보고하고자 한다.

• Structural Monitoring and Maintenance
• /
• 제5권1호
• /
• pp.151-171
• /
• 2018

Transmission tower-line systems are commonly slender and generally possess a small stiffness and low structural damping. They are prone to impulsive excitations induced by cable rupture and may experience strong vibration. Excessive deformation and vibration of a transmission tower-line system subjected to cable rupture may induce a local destruction and even failure event. A little work has yet been carried out to evaluate the performance of transmission tower-line systems in mountain areas subjected to cable rupture. In addition, the control for cable rupture induced vibration of a transmission tower-line system has not been systematically conducted. In this regard, the dynamic response analysis of a transmission tower-line system in mountain areas subjected to cable rupture is conducted. Furthermore, the feasibility of using viscous fluid dampers to suppress the cable rupture-induced vibration is also investigated. The three dimensional (3D) finite element (FE) model of a transmission tower-line system is first established and the mathematical model of a mountain is developed to describe the equivalent scale and configuration of a mountain. The model of a tower-line-mountain system is developed by taking a real transmission tower-line system constructed in China as an example. The mechanical model for the dynamic interaction between the ground and transmission lines is proposed and the mechanical model of a viscous fluid damper is also presented. The equations of motion of the transmission tower-line system subjected to cable rupture without/with viscous fluid dampers are established. The field measurement is carried out to verify the analytical FE model and determine the damping ratios of the example transmission tower-line system. The dynamic analysis of the tower-line system is carried out to investigate structural performance under cable rupture and the validity of the proposed control approach based on viscous fluid dampers is examined. The made observations demonstrate that cable rupture may induce strong structural vibration and the implementation of viscous fluid dampers with optimal parameters can effectively suppress structural responses.

• 한국강구조학회 논문집
• /
• 제27권1호
• /
• pp.1-12
• /
• 2015

잘 접합된 볼트접합부는 볼트의 전단파단이 발생할 때 까지 지압 메커니즘에 의하여 훌륭한 연성거동을 보인다. 이러한 볼트접합부에 내재된 연성 능력을 최대한 활용한다면 중력하중, 풍하중, 지진하중 등 다양한 하중에 대하여 활용하여 접합비용의 경제성 제고에 기여할 수 있다. 편심하중을 받는 볼트접합부의 경우 보수적인 탄성해석법과 합리적으로 볼트접합부의 연성거동을 활용할 수 있는 극한강도 해석법이 존재하나 기존의 극한강도해석법은 오늘날 다양한 소재와 설계조건의 다양화에도 불구하고 하나의 소재와 조건으로 이루어진 실험식에 의존하고 있다. 본 연구의 주된 목적은 체계화된 단일볼트의 실험을 기반으로 볼트의 일반화된 힘-변형 관계식을 정립하는 것이다. 실험결과를 토대로 볼트접합부의 기하학적인 요소(볼트의 직경, 플레이트의 두께) 및 강도가 힘-변형 관계에 주된 영향을 미치는 요소라는 것을 알 수 있다. 실험결과를 순간중심회전법에 적용하여 보다 정확하고 경제적인 편심하중을 받는 군볼트 접합부 설계가 가능하다.

• Steel and Composite Structures
• /
• 제19권6호
• /
• pp.1581-1598
• /
• 2015

A concentric braced steel frame is a very efficient structural system because it requires relatively smaller amount of materials to resist lateral forces. However, primarily developed as a structural system to resist wind loads based on an assumption that the structure behaves elastically, a concentric braced frame possibly experiences the deterioration in energy dissipation after brace buckling and the brittle failure of braces and connections when earthquake loads cause inelastic behavior. Consequently, plastic deformation is concentrated in the floor where brace buckling occurs first, which can lead to the rupture of the structure. This study suggests reinforcing H-shaped braces with non-welded cold-formed stiffeners to restrain flexure and buckling and resist tensile force and compressive force equally. Weak-axis reinforcing members (2 pieces) developed from those suggested in previous studies (4 pieces) were used to reinforce the H-shaped braces in an inverted V-type braced frame. Monotonic loading tests, finite element analysis and cyclic loading tests were carried out to evaluate the structural performance of the reinforced braces and frames. The reinforced braces satisfied the AISC requirement. The reinforcement suggested in this study is expected to prevent the rupture of beams caused by the unbalanced resistance of the braces.