Joint Statistics of Natural Frequencies Corresponding to Structural Systems with Singular Random Parameter Matrices

2022 ◽  
Vol 148 (3) ◽  
Author(s):  
Vasileios C. Fragkoulis ◽  
Ioannis A. Kougioumtzoglou ◽  
Athanasios A. Pantelous ◽  
Michael Beer
Keyword(s):  
Natural Frequencies ◽  
Random Parameter ◽  
Structural Systems

scholarly journals Robust H∞ Control of STMDs Used in Structural Systems by Hardware in the Loop Simulation Method

Actuators ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 55
Author(s):  
Huseyin Aggumus ◽  
Rahmi Guclu
Keyword(s):  
Natural Frequencies ◽  
Experimental Studies ◽  
Mr Damper ◽  
Simulation Method ◽  
Control Element ◽  
Structural Systems ◽  
Hardware In The Loop ◽  
Building Model ◽  
Mass Damper ◽  
Set Up

This paper investigated the performance of a semi-active tuned mass damper (STMD) on a multi-degree of freedom (MDOF) building model. A magnetorheological (MR) damper was used as a control element that provided semi-activity in the STMD. The Hardware in the Loop Simulation (HILS) method was applied to mitigate the difficulty and expense of experimental studies, as well as to obtain more realistic results from numerical simulations. In the implementation of this method for the STMD, the MR damper was set up experimentally, other parts of the system were modeled as computer simulations, and studies were carried out by operating these two parts simultaneously. System performance was investigated by excitation with two different acceleration inputs produced from the natural frequencies of the MDOF building. Additionally, a robust H ∞ controller was designed to determine the voltage transmitted to the MR damper. The results showed that the HILS method could be applied successfully to STMDs used in structural systems, and robust H ∞ controls improve system responses with semi-active control applications. Moreover, the control performance of the MR damper develops with an increase in the mass of the STMD.

scholarly journals Component Mode Synthesis Method Applied to Acoustic Resonators in Ducts for Structural Vibration Analysis

2020 ◽  
Vol 25 (4) ◽  
pp. 498-503
Author(s):  
Jose Manuel Bautista Ordóñez ◽  
Maria Alzira de Araújo Nunes
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Component Mode Synthesis ◽  
Structural Vibration ◽  
Structural Systems ◽  
Vibration Modes ◽  
The Finite Element Method ◽  
Element Method

Tubular structural systems appear in many industrial applications, such as heating, ventilation, and air conditioning systems, which are responsible for making any enclosed environment remain within a temperature, humidity, and cleanliness range. This kind of system has its applications in the internal environmental comfort of industrial spaces, buildings, and vehicles. Several of these spaces have industrial processes that generate high sound frequencies and mechanical vibrations that need to be adequately controlled to meet both environmental and health norms. With the intention to analyze the structural vibration of tubular systems, the modal analysis technique is a classical methodology for the extraction of natural frequencies and vibration modes. Among the various techniques of modal analysis, numerical methodologies such as the finite element method, and also analytical methodologies such as the Component Mode Synthesis (CMS) can be found. CMS is one of the leading modeling tools for complex systems that are applied to large systems. The method uses a modal superset and consists of separately modeling individual components of a structure and coupling them into a single system. The objective of this work is to demonstrate the application of the CMS technique through the estimation of natural frequencies and vibration modes in a simplified tubular structural system formed by two substructures, using MATLAB and ANSYS. The validation of the results was done through numerical modeling using the finite element method using and ANSYS software. The results obtained were satisfactory, thus demonstrating the feasibility of applying the CMS technique to an analysis of structural vibration in tubular structural systems.

scholarly journals Narrowband Control Design for Smart Structural Systems

2001 ◽  
Author(s):  
Daniel J. Kolepp ◽  
Ralph C. Smith
Keyword(s):  
Discrete System ◽  
Natural Frequencies ◽  
Control Method ◽  
Control Strategies ◽  
Control Design ◽  
Structural Systems ◽  
Pde Model ◽  
Finite Dimensional ◽  
Initial Control ◽  
Physical Attributes

Abstract This investigation focuses on the development of narrowband control strategies which are effective for structural systems subjected to both harmonic exogenous forces and stochastic uncertainties in the model or measurements. A cantilever beam with surface-mounted piezoceramic actuators is used as a prototypical structure since it exhibits physical attributes of a variety of vibrating structures but is sufficiently simple to facilitate initial control design. A PDE model for the structure is discretized using a spline-based Galerkin technique to obtain a semi-discrete system that is appropriate for finite-dimensional control design. A narrowband control method, which can be tuned to attenuate either natural frequencies or specific frequencies in the exogenous input, is developed and compared with standard LQR techniques through numerical examples.

scholarly journals Open and closed shear-walls in high-rise structural systems: Static and dynamic analysis

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Alberto Carpinteri ◽  
Giuseppe Lacidogna ◽  
Giuseppe Nitti
Keyword(s):  
Dynamic Analysis ◽  
Degrees Of Freedom ◽  
Natural Frequencies ◽  
Torsional Rigidity ◽  
Shear Walls ◽  
Mode Shapes ◽  
Structural Systems ◽  
Preliminary Design ◽  
Static And Dynamic Analysis ◽  
High Rise

AbstractIn the present paper, a General Algorithm is applied to the analysis of high-rise structures. This algorithm is to be used as a calculation tool in preliminary design; it allows to define the interaction between closed and open, straight or curved shear-walls, and the forces exchanged in structures subject to mainly horizontal loads. The analysis can be performed in both static and dynamic regimes, the mode shapes and the natural frequencies being assessed. This general formulation allows analyses of high-rise structures by taking into account the torsional rigidity and the warping deformations of the elements composing the building without gross simplifications. In thisway it is possible to model the structure as a single equivalent cantilever, thus minimising the degrees of freedom of the system, and consequently the calculation time. Finally, potentials of the method proposed are demonstrated by a numerical example which emphasizes the link between global displacements and stresses in the elements composing the structure.

scholarly journals Some relevant aspects of footbridge vibrations

2002 ◽  
Vol 2 (4) ◽  
pp. 281-289
Author(s):  
Ana Spasojevic ◽  
Djordje Djordjevic ◽  
Marija Spasojevic ◽  
Novak Spasojevic
Keyword(s):  
Structural Design ◽  
Natural Frequencies ◽  
Weight Ratio ◽  
Structural Systems ◽  
Live Load ◽  
Limit States ◽  
Codes Of Practice ◽  
Vibration Serviceability ◽  
Bridge Structures ◽  
Ultimate Limit

Considering the contemporary structural inaterials that are becoming more resistant, having higher strength to weight ratio, and the fact that live load of footbridges is low, the design based on static analysis only, respecting ultimate limit states requirements, leads to slender bridge structures for pedestrian and cycle track use. As a consequence, stiffness and masses decrease, facing lively, easy to excite structures, with smaller natural frequencies. The excitation of a footbridge by a pedestrian passing over it can be unpleasant for a person walking or standing on the bridge, but usually not destructive for the structure itself. Recent experiences regarding dynamic behavior of slender footbridges have especially shown that vibration serviceability limit states are very important requirements in any structural design. We are presenting a general algorithm for analytical testing of dynamic parameters of structures, calculation of deflection, thus speed and acceleration of superstructure under human-induced excitation, as predicted by Eurocode, British and Canadian standards in use, since no Yugoslav code deals with the problem. The evaluated system is a footbridge in a system of a simply supported concrete girder. The presented model is used to show correspondence of results, obtained by the algorithm, with the results obtained using the simplified methods suggested by the Codes of Practice, since the latter exists only for certain structural systems.

Static–Dynamic Relationship for Flexural Free Vibration of Extensible Beams

2018 ◽  
Vol 18 (09) ◽  
pp. 1871010 ◽  
Author(s):  
Zhenyu Chen ◽  
C. W. Lim
Keyword(s):  
Free Vibration ◽  
Vibration Analysis ◽  
Natural Frequencies ◽  
Free Vibration Analysis ◽  
Technical Note ◽  
Structural Systems ◽  
Vibration System ◽  
Dynamic Relationship ◽  
Static Approach ◽  
Vibration Problems

This technical note presents a static–dynamic relationship for the flexural free vibration analysis of beams in tension with some specific boundary conditions. It is shown to be possible that a free vibration system can be solved via a static analysis approach to determine the natural frequencies of the beam with tension forces. The key idea of this study is to substitute the real natural frequency parameters with zero or negative elastic foundation stiffness, thereby allowing one to obtain the natural frequencies by analyzing the case with negative foundation elastic constant. This static approach for vibration problems can be extended for more complicated engineering structural systems.

POST-TENSIONED STRUCTURAL SYSTEMS - DALLAS-FT. WORTH AIRPORT

PCI Journal ◽  
1973 ◽  
Vol 18 (6) ◽  
pp. 72-91
Author(s):  
Eugene A. Lamberson
Keyword(s):  
Structural Systems ◽  
Post Tensioned

Numerical Method for Hetero-Cavities Natural Frequencies’ Determination

2016 ◽  
Vol 10 (3) ◽  
pp. 141
Author(s):  
Fethi Maiz ◽  
Ridha Chouikh ◽  
Amenallah Guizani
Keyword(s):  
Numerical Method ◽  
Natural Frequencies
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