• Journal of the Korea institute for structural maintenance and inspection
• /
• v.13 no.3 s.55
• /
• pp.225-231
• /
• 2009

This study introduces the CFTA girder(Concrete-Filled and Tied Steel Tubular Arch Girder) which is a combined structural system of traditional CFT, arch, and prestress structures. Static load tests and structural behavior analyses were carried out for a 25m long CFTA girder. In the analysis, each load of 58kN, 88kN, 148kN, 207kN,and 298kN was applied incrementally at the positions of 1.0 m distances in both directions from the center of the girder. On each test, strain and displacement were measured. Linear static FEM analyses using Strand7 code were also performed to check the structural stability and to investigate the effects of prestressing(${\pm}$20%) and material property(Young's modulus) on the displacement and strain. The results of this study are summarized as follows: the initial strain & displacement under selfweight and prestressing were influenced with the variation of prestressing, but they were mainly effected only by Young's modulus when additional loads were applied.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1999.04a
• /
• pp.203-209
• /
• 1999

In this study, the structural deflection analysis of robot manipulator for removing nuclear fuel rod from nuclear reactor vessel is performed by using general purpose finite element code (ANSYS). The structural deflection analysis results reported in this study is very required for the accurate design of robot system. The structural deflection analysis for the manipulator's structural status at which the gripper grasps and draws up the nuclear fuel rod is done, For this beginning structural status of robot manipulator's removing motion, the reaction forces at each joint have static maximum values as reported in the reference(6), and so these forces may cause the maximum deflection of robot structure. The structural deflection analysis is performed for selected four working cases of the proposed structural model and results on deformation, stress for the manipulator's solid body and the deflection at the end of robot manipulator's gripper are calculated. And further, the same analysis is performed for the slenderer manipulator with cross section reduced by one-fifth of each side length of proposed model. The analysis is performed not only for the nuclear fuel rod with weight load of 300kg but also for nuclear fuel rods with weight loads of 100kg, 200kg, 400kg and 500kg. The static structural deflection analysis results show that the deflection value increases as the load increases and the largest value (corresponding to the weight load of 500kg in case 1) is much smaller than the gap distance between nuclear fuel rods. but the largest value for the slenderer manipulator is almost as large as the gap distance, Hence, conclusively, the proposed manipulator's structural model is acceptably safe for mechanical design of robot system.

• Smart Structures and Systems
• /
• v.3 no.1
• /
• pp.23-49
• /
• 2007

Wavelet transforms are the emerging signal-processing tools for damage identification and time-frequency localization. A small perturbation in a static or dynamic displacement profile could be captured using multi-resolution technique of wavelet analysis. The paper presents the wavelet analysis of damaged linear structural elements using DB4 or BIOR6.8 family of wavelets. Starting with a localized reduction of EI at the mid-span of a simply supported beam, damage modeling is done for a typical steel and reinforced concrete beam element. Rotation and curvature mode shapes are found to be the improved indicators of damage and when these are coupled with wavelet analysis, a clear picture of damage singularity emerges. In the steel beam, the damage is modeled as a rotational spring and for an RC section, moment curvature relationship is used to compute the effective EI. Wavelet analysis is performed for these damage models for displacement, rotation and curvature mode shapes as well as static deformation profiles. It is shown that all the damage indicators like displacement, slope and curvature are magnified under higher modes. A localization scheme with arbitrary location of curvature nodes within a pseudo span is developed for steady state dynamic loads, such that curvature response and damages are maximized and the scheme is numerically tested and proved.

• Aerospace Engineering and Technology
• /
• v.3 no.2
• /
• pp.72-80
• /
• 2004

LOX pump is one of the sub-assemblies constructing turbopump unit. In the current study, static structural analysis on such rotating parts as impeller and inducer has been carried out. Three major factors which can affect the structural stability of the rotating parts of LOX pump, are temperature, pressure, and centrifugal force. The effect of each factor was preliminarily investigated, then the analysis under the consideration of the combined loading conditions has been carried out. The major factor that affects the structural stability was proved to be temperature. The analyses of the combined cases showed that the designed impeller and inducer had reasonable safety margins, which means that the impeller and the inducer will be stable in static structural strength. Although there was no problem in the structural strength of the impeller and the inducer, a model analysis should be followed in order to verify the interference between the rotating part and the inner surface of casing.

• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.3
• /
• pp.265-274
• /
• 2011

This paper presents current state of the prediction simulator of structural characteristics of machinery equipment accuracy. Developed accuracy prediction simulator proceeds and estimates the structural analysis between the designer and simulator through the internet for convenience of designer. 3D CAD model which is input to the accuracy prediction simulator would simplified by the process of removing the small hole, fillet and chamfer. And the structural surface joints would be presented as the spring elements and damping elements for the structural analysis. The structural analysis of machinery equipment joints, containing rotary motion unit, linear motion unit, mounting device and bolted joint, are presented using Finite Element Method and their experiment. Finally, a general method is presented to tune the static stiffness at a rotation joint considering the whole machinery equipment system by interactive use of Finite Element Method and static load experiment.

• Steel and Composite Structures
• /
• v.26 no.5
• /
• pp.549-556
• /
• 2018

Progressive building collapse occurs when failure of a structural component leads to the failure and collapse of surrounding members, possibly promoting additional failure. Global system collapse will occur if the damaged system is unable to reach a new static equilibrium configuration. The most common type of primary failure which led to the progressive collapse phenomenon, is the sudden removal of a column by various factors. In this study, a method is proposed to prevent progressive collapse phenomena in structures subjected to removal of a single column. A vierendeel peripheral frame at roof level is used to redistribute the removed column's load on other columns of the structure. For analysis, quasi-static approach is used which considers various load combinations. This method, while economically affordable is easily applicable (also for new structures as well as for existing structures and without causing damage to their architectural requirements). Special emphasis is focused on the evolution of vertical displacements of column removal point. Even though additional stresses and displacements are experienced by removal of a structural load bearing column, the proposed method considerably reduces the displacement at the mentioned point and prevents the collapse of the structural frame.

• Smart Structures and Systems
• /
• v.26 no.5
• /
• pp.667-680
• /
• 2020

This study aims at reporting a systematic procedure for evaluating the static and dynamic structural performance of steel bridges based on a short-period structural health monitoring measurement. Sungsu bridge located in Korea is considered as a case study presenting the most recent tests carried out to examine the bridge condition. Short-period measurements of Structural Health Monitoring (SHM) system were used during the bridge testing phase. A novel symmetry index is introduced using statistical analyses of deflection and strain measurements. Frequency Domain Decomposition (FDD) is implemented to the strain measurements to estimate the bridge mode shapes and damping ratios. Furthermore, Markov Chain Monte Carlo (MCMC) is also implemented to examine the reliability of bridge performance while ambient design trucks are in static or moving at different speeds. Strain, displacement and acceleration were measured at selected locations on the bridge. The results show that the symmetry index can be an efficient and useful measure in assessing the steel bridge performance. The results from the used method reveal that the performance of the Sungsu bridge is safe under operational conditions.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.10
• /
• pp.882-889
• /
• 2008

A humanoid is a robot with its overall appearance based on that of the human body. When the humanoid moves or walks, dynamic forces act on the body structure. Although the humanoid keeps the balance by using a precise control, the dynamic forces generate unexpected deformation or vibration and cause difficulties on the control. Generally, the structure of the humanoid is designed by the designer's experience and intuition. Then the structure can be excessively heavy or fragile. A humanoid design scenario for a systematic design is proposed to reduce the weight of the structure while sufficient strength is kept. Lower parts of the humanoid are selected to apply the proposed design scenario. Multi-body dynamics is employed to calculate the external dynamic forces on the parts and structural optimization is carried out to design the lower parts. Because structural optimization using dynamic forces directly is fairly difficult, linear dynamic response structural optimization using equivalent static loads is utilized. Topology and shape optimizations are adopted for two steps of initial and detailed designs, respectively. Various commercial software systems are used for analysis and optimization. Improved designs are obtained and the design results are discussed.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.16 no.4
• /
• pp.486-492
• /
• 2013

The pivoting composite wing is developed for the kit to be mounted on the external stores. The wing has a pivoting structure for the installation to an aircraft and high aspect ratio to increase lift drag ratio. The wing needs to be light and have sufficient strength and stiffness to satisfy structural design requirements. The wing is designed with carbon fiber composite and the structural parts are integrated to reduce cost to manufacture. In order to verify the structural performances, the design load analysis and flight load survey, the static analysis and test, the ground vibration test and flutter analysis are performed. It is shown that the wing has sufficient structural strength and stiffness to satisfy the structural design requirements.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.5
• /
• pp.569-576
• /
• 2011

In this paper a new analysis procedure for evaluation of progressive collapse resisting capacity of a structure was proposed based on the nonlinear static analysis procedure. The proposed procedure produces analysis results identical to those obtained by the linear static analysis procedure specified in the GSA guidelines without iteration, therefore saving a lot of computation time and excluding the possibility of human errors during the procedure. To verify the validity of the proposed procedure, the two methods were applied to the analysis of a reinforced concrete moment frame and a steel braced frame subjected to loss of a first story column and the results were compared. According to the analysis results, the two methods produce identical results in the prediction of progressive collapse and the hinge formation. As iterative analysis is not required in the proposed method, significant amount of analysis time is saved in the proposed analysis procedure.