• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2001.10a
• /
• pp.117-126
• /
• 2001

In this study, the recently developed unscented Kalman filter (UKF) technique is studied for identification of nonlinear structural dynamic systems as an alternative to the extended Kalman filter (EKF). The EKF, which was originally developed as a state estimator for nonlinear systems, has been frequently employed for parameter identification by introducing the state vector augmented with the unknown parameters to be identified. However, the EKF has several drawbacks such as biased estimations and erroneous estimations especially for highly nonlinear dynamic systems due to its crude linearization scheme. To overcome the weak points of the EKF, the UKF was recently developed as a state estimator. Numerical simulation studies have been carried out on nonlinear SDOF system and nonlinear MDOF system. The results from a series of numerical simulations indicate that the UKF is superior to the EKF in the system identification of nonlinear dynamic systems especially highly nonlinear systems.

• Structural Engineering and Mechanics
• /
• v.20 no.1
• /
• pp.111-121
• /
• 2005

The dynamic interaction of vehicle-bridge is studied by using transfer matrix method in this paper. The vehicle model is simplified as a spring-damping-mass system. By adopting the idea of Newmark-${\beta}$ method, the partial differential equation of structure vibration is transformed into a differential equation irrelevant to time. Then, this differential equation is solved by transfer matrix method. The prospective application of this method in real engineering is finally demonstrated by several examples.

• Smart Structures and Systems
• /
• v.29 no.5
• /
• pp.715-728
• /
• 2022

Recently, numbers of long span pedestrian suspension bridges have been constructed worldwide. While recent tragedies regarding pedestrian suspension bridges have shown how these bridges can wreak havoc on the society, there are no specific guidelines for construction standards nor safety inspections yet. Therefore, a structural health monitoring system that could help ensure the safety of pedestrian suspension bridges are needed. System identification is one of the popular applications for structural health monitoring method, which estimates the dynamic system. Most of the system identification methods for bridges are currently adapting output-only system identification method, which assumes the dynamic load to be a white noise due to the difficulty of measuring the dynamic load. In the case of pedestrian suspension bridges, the pedestrian load is within specific frequency range, resulting in large errors when using the output-only system identification method. Therefore, this study aims to develop a system identification method for pedestrian suspension bridges considering both input and output of the dynamic system. This study estimates the location and the magnitude of the pedestrian load, as well as the dynamic response of the pedestrian bridges by utilizing artificial intelligence and computer vision techniques. A simulation-based validation test was conducted to verify the performance of the proposed system. The proposed method is expected to improve the accuracy and the efficiency of the current inspection and monitoring systems for pedestrian suspension bridges.

• Structural Engineering and Mechanics
• /
• v.32 no.3
• /
• pp.399-406
• /
• 2009

A three-dimensional panel system, which was offered as a new method for construction in Jordan using relatively high strength modular panels for walls and ceilings, is investigated in this paper. The panel consists of two steel meshes on both sides of an expanded polystyrene core and connected together with a truss wire to provide a 3D system. The top face of the ceiling panel was pored with regular concrete mix, while the bottom face and both faces of the wall panels were cast by shotcreting (dry process). To investigate the structural performance of this system, an extensive experimental testing program for ceiling and wall panels subjected to static and dynamic loadings was conducted. The load-deflection curves were obtained for beam and shear wall elements and wall elements under transverse and axial loads, respectively. Static and dynamic analyses were conducted, and the performance of the proposed structural system was evaluated and compared with a typical three dimensional reinforced concrete frame system for buildings of the same floor areas and number of floors. Compressive strength capacity of a ceiling panel is determined for gravity loads, while flexural capacity is determined under the effect of wind and seismic loading. It was found that, the strength and serviceability requirements could be easily satisfied for buildings constructed using the three-dimensional panel system. The 3D panel system is superior to that of conventional frame system in its dynamic performance, due to its high stiffness to mass ratio.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2006.04a
• /
• pp.667-674
• /
• 2006

Dynamic analysis of the electrical transmission system including transmission towers and cables is carried out by a general purpose structural analysis computer program for examining the wind-resistance of the system The spectral representation method is introduced to generate dynamic wind loads by using the Kaimal's spectrum and the measured wind velocities from wind tunnel tests, respectively. The numerical simulation results show that the responses in the case of the measured wind velocities is slightly larger than those in the case of the code.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2004.10a
• /
• pp.108-111
• /
• 2004

Structural dynamic characteristics and aeroelastic stability of a small-scale bearingless rotor system have been investigated. A flexbeam is one of the most important component of bearingless hub system. It must have sufficient torsional flexibility as well as baseline stiffness in order to produce feathering motion. In the present paper, a cross-shaped composite flexbeam has been proposed for a guarantee of torsional flexibility and flapwise and lagwise bending stiffness. One dimensional elastic beam model was used for the construction of a structural model. Equivalent isotropic sectional stiffness was used in the blade model, and the flexbeam was regarded as anisotropic; which has ten independent stiffness quantities. CAMRAD II has been used for the analysis of structural dynamic characteristics of the bearingless rotor system. Rotational natural frequencies and aeroelastic stability at hovering have been investigated. Analysis result shows that the cross-shaped flexbeam has the rotational natural frequency tuning capacity.

• Korean Journal of Computational Design and Engineering
• /
• v.7 no.1
• /
• pp.27-33
• /
• 2002

MDO(Multidisciplinary Design Optimization) methodology is a new technology to solve a complicate design problem with a large number of design variables and constraints. The design of a dental implant system is a typical complicate problem, and so it requires the MDO methodology. Actually, several analyses such as rigid body dynamic analysis and structural stress analysis etc. should be carried out in the MDO methodology application to the design of a dental implant system. In this paper, as a first step of MDO methodology application to the design of a dental implant system, the impact force which is applied on the tooth in masticating is calculated through the rigid body dynamic analysis of upper and lower jaw-bones. This analysis is done using ADAMS. The impact force calculated through the rigid body dynamic analysis can be used for the structural stress analysis of a dental implant system which is needed for the design of a dental implant system. In addition, the rigid body dynamic analysis results also show that the impact time decreases as the impact force increases, the largest impact force occurs on the front tooth, and the impact force is almost normal to the tooth surface with a slight tangential force.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2001.10a
• /
• pp.475-482
• /
• 2001

Stadium stand could be led to significant dynamic response due to rhythmical activities of spectator. The dynamic loads induced by spectators movements are considered as static loads in design standard of many countries but these loads have dynamic characteristics. So, it is desirable to apply measured dynamic loads created by spectator activities and to analyze the dynamic behavior of stadium system. The precise investigation of the dynamic loads on stadium structures and the accurate analysis of dynamic behavior of stadium systems are demanded for effective design. As the floor mesh of stadium stand is refined, the number of nodes increase in numerical analysis. So it is difficult to analyze entire stadium structures and much more computer memory are necessary for vibration analysis of stadium system. In this study, the various dynamic loads induced by spectator movements are measured and analyzed. And new modeling method that reduce the nodal points of stadium systems are introduced. Vibration analysis of stadium system is executed to inspect the accuracy and the efficiency of proposed method in this paper.

• Journal of KSNVE
• /
• v.3 no.1
• /
• pp.65-75
• /
• 1993

In this study, we identify the structural dynamic characteristics of the rigid body suspension system of waching machine containing rotating system, and consider the methods for the reduction of noise and vibration due to the structural problems. The structural dynamic characteristics of the suspension system have been studied by the computer simulation, in which the commercial software package, "DYMES(Dynamics of Mechanical System)" is used. The behaviour of the supporter by the rotating system has been parametrically studied by computer simulation, and the force and torque which are transferred to the fixed body through the suspension bar also has been calculated. The possibility to decide the position and the stability of the rigid body suspension system for waching machine is demonstrated based on various simulation results.n results.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2003.10a
• /
• pp.47-54
• /
• 2003

The rotating of rotatory unit with its structural unbalance mass and laundry is making the main vibration problem in a vertical axis washing machine. For reducing vibration problem total washing system hung on the case by its suspension system which is constitute of spring, damper and suspension bar and hydraulic balancer is attached at the upper rim of spin basket. In this paper, we make the dynamic model of washing system of its rigid body motions by 6 degree of freedoms. Hydraulic balancer is modeled by one degree of freedom like auto ball balancer. Elastic motions of washing system have found by method of analytic, experimental and FEM. And we consider first bending mode of each suspension bar and first circumferential mode of assy tub. So, the total washing system is modeled by 12 degree of freedoms. Equations of motion for total washing system have derived, and we perform the dynamic simulation tests.