scholarly journals Investigation of the Performance of Two Passive Controllers in Mitigating the Rotational Response of Irregular Buildings

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Yasser Bigdeli ◽  
Dookie Kim
Keyword(s):  
Dynamic Loads ◽  
Structural Vibration ◽  
Seismic Loads ◽  
Tuned Liquid Damper ◽  
Water Level Changes ◽  
Power Spectral ◽  
Control Devices ◽  
Rotational Response ◽  
Rotational Direction ◽  
Critical Direction

Two passive vibration control devices (i.e., circle type tuned liquid damper (C-TLD) and a circle type tuned liquid column damper (C-TLCD)) were experimentally investigated for their performance when attached to the irregular building structure subjected to dynamic loads. The specific directions where the maximum response of the structure is expected were experimentally identified for x- and y-directions as well as for rotational direction. The power spectral density (PSD) was computed for the response of the structure based on the frequency of the first three modes and also water level changes in the device container by using fast Fourier transform (FFT). The performances of these two controllers regarding suppressing the structural vibration were compared for the seismic loads applied in an experimentally identified critical direction. The results show that these systems are effective in terms of mitigating the coupled lateral and torsional vibrations of a scaled three-story irregular model.

scholarly journals Analytical corrections for double-cantilever beam tests

2021 ◽  
Author(s):  
T. Chen ◽  
C. M. Harvey ◽  
S. Wang ◽  
V. V. Silberschmidt
Keyword(s):  
Elastic Foundation ◽  
Analytical Solutions ◽  
Data Reduction ◽  
Crack Tip ◽  
Beam Theory ◽  
Dynamic Loads ◽  
Structural Vibration ◽  
Mode I ◽  
Mode I Fracture ◽  
Reduction Methods

AbstractDouble-cantilever beams (DCBs) are widely used to study mode-I fracture behavior and to measure mode-I fracture toughness under quasi-static loads. Recently, the authors have developed analytical solutions for DCBs under dynamic loads with consideration of structural vibration and wave propagation. There are two methods of beam-theory-based data reduction to determine the energy release rate: (i) using an effective built-in boundary condition at the crack tip, and (ii) employing an elastic foundation to model the uncracked interface of the DCB. In this letter, analytical corrections for a crack-tip rotation of DCBs under quasi-static and dynamic loads are presented, afforded by combining both these data-reduction methods and the authors’ recent analytical solutions for each. Convenient and easy-to-use analytical corrections for DCB tests are obtained, which avoid the complexity and difficulty of the elastic foundation approach, and the need for multiple experimental measurements of DCB compliance and crack length. The corrections are, to the best of the authors’ knowledge, completely new. Verification cases based on numerical simulation are presented to demonstrate the utility of the corrections.

Refined Mathematical Models for Across-Wind Loads of Rectangular Tall Buildings with Aerodynamic Modifications

2021 ◽  
pp. 2150131
Author(s):  
Yi Li ◽  
Chao Li ◽  
Qiu-Sheng Li ◽  
Yong-Gui Li ◽  
Fu-Bin Chen
Keyword(s):  
Wind Tunnel ◽  
Correlation Coefficients ◽  
Tall Buildings ◽  
Tall Building ◽  
Experimental Results ◽  
Dynamic Loads ◽  
Wind Loads ◽  
Empirical Formulas ◽  
Benchmark Model ◽  
Power Spectral

This paper aims to systematically study the across-wind loads of rectangular-shaped tall buildings with aerodynamic modifications and propose refined mathematic models accordingly. This study takes the CAARC (Commonwealth Advisory Aeronautical Research Council) standard tall building as a benchmark model and conducts a series of pressure measurements on the benchmark model and four CAARC models with different round corner rates (5%, 10%, 15% and 20%) in a boundary layer wind tunnel to investigate the across-wind dynamic loads of the typical tall building with different corner modifications. Based on the experimental results of the five models, base moment coefficients, power spectral densities and vertical correlation coefficients of the across-wind loads are compared and discussed. The analyzed results shown that the across-wind aerodynamic performance of the tall buildings can be effectively improved as the rounded corner rate increases. Taking the corner round rate and terrain category as two basic variables, empirical formulas for estimating the across-wind dynamic loads of CAARC standard tall buildings with various rounded corners are proposed on the basis of the wind tunnel testing results. The accuracy and applicability of the proposed formulas are verified by comparisons between the empirical formulas and the experimental results.

scholarly journals Evaluation of the Structural Stability of an Octagonal Dome with Meridional Cracks. Case Study: Temple of Santa Lucia, Ambalema, Colombia

2017 ◽  
Vol 2 (2) ◽  
pp. 25
Author(s):  
Jorge Olmedo Montoya ◽  
Olimpia Niglio ◽  
Karol Brigith Romero
Keyword(s):  
Structural Stability ◽  
Dynamic Loads ◽  
Seismic Events ◽  
Seismic Loads ◽  
Construction Process ◽  
Analysis Software ◽  
Historical Structures ◽  
The Temple ◽  
Typical Process

This work performed a comparative analysis between the construction process carried out when building the dome at the Temple of Santa Lucía, in Ambalema-Colombia and the typical process of an octagonal dome. Additionally, the structural stability is assessed of the dome of the case study against service and dynamic loads. To compare with the case study, known domes were taken as examples from structures in Italy and Spain. The analysis includes a study on the dome’s geometry and the constructive errors found. Methodology: The dome’s stability was evaluated through structural analysis software for which the dome was simplified into a system of four articulated arches. Conclusions: As a result, it was found that the dome of the temple of Santa Lucía does not have a system to counteract lateral thrusts (a drum or its similar), which permitted the appearance and widening of meridional cracks. These cracks propagate from the base to the crown, but do not compromise the structure’s stability for service loads. The analysis for seismic loads indicates that the dome is at risk of collapse upon seismic events, even of moderate magnitudes. Originality: The study is aimed at architects and engineers interested in the theme of restoration of historical structures.

Dynamic Response of a Steel-Concrete Hybrid Frame to Support 15MW Compressor

2012 ◽  
Author(s):  
Seunghoon Shin ◽  
Guangyoung Sun ◽  
Juwon Lee ◽  
Kangboo Kim
Keyword(s):  
Dynamic Analysis ◽  
Structural Dynamics ◽  
Structural Design ◽  
Modal Testing ◽  
Dynamic Loads ◽  
Structural Vibration ◽  
Aerodynamic Load ◽  
Radial Load ◽  
Structural Dynamic ◽  
Test Result

In this paper, the structural dynamics study of the frame to support 15MW compressor is suggested. This study used the steel-concrete hybrid frame to support a large compressor system. This paper provided experimental and analytical method to structural design the hybrid frame by considering in rotordynamics and aerodynamics. Dynamic characteristics of the frame have to be identified to tune the finite element model’s boundary condition and to avoid resonance. Therefore modal testing of the frame is performed and boundary conditions are modified applying to the previously obtained modal parameters. While compressor is operated, multiple dynamic loads of compressor, motor and expander may excite on the frame. The total dynamic load is derived by axial aerodynamic load of impeller, radial load of gear and unbalance load of rotor. After dynamic analysis completion, the analysis result is compared with test result to verify the accuracy of analysis. Through this structural dynamic analysis, structural vibration response of hybrid frame can be estimated.

Modeling and Identification of a Large-Scale Magnetorheological Fluid Damper

2008 ◽  
Vol 56 ◽  
pp. 374-379
Author(s):  
Arturo Rodriguez ◽  
N. Iwata ◽  
Fayçal Ikhouane ◽  
José Rodellar
Keyword(s):  
Large Scale ◽  
Dynamic Loads ◽  
Control System Design ◽  
Mr Dampers ◽  
Highly Nonlinear ◽  
Fluid Damper ◽  
Control Devices ◽  
Simulation And Control ◽  
Mr Fluid Damper ◽  
And Control

In the last years there has been an increasing interest to magnetorheological (MR) dampers and their applications to civil engineering. In particular they have been used as semi-active control devices for vibration mitigation due to external dynamic loads. These devices are highly nonlinear and thus accurate models of these devices are important for effective simulation and control system design. Two hysteretic models based on the normalized Bouc-Wen model are proposed in this paper to compare their effectiveness in a large scale MR fluid damper. A methodology for identification is proposed, and the obtained models are tested and validated experimentally.

Connecting Parameter Study on Adjacent Structures Linked by Dampers

2011 ◽  
Vol 243-249 ◽  
pp. 3832-3838
Author(s):  
Huang Sheng Sun ◽  
Li Nuo Cheng
Keyword(s):  
Damping Ratio ◽  
Structural Vibration ◽  
Parameter Study ◽  
Optimal Parameters ◽  
Seismic Responses ◽  
Earthquake Excitation ◽  
Power Spectral ◽  
Adjacent Structures ◽  
Distribution Of Power ◽  
Seismic Mitigation

In order to research the optimal parameters of dampers linking adjacent structures for seismic mitigation, two SDOF systems connected with visco-elastic damper (VED) are taken as research object and the primary structural vibration frequency ratio, connection stiffness and linking damping ratio as research parameters. Modified Kanai-Tajimi spectrum is selected to model the earthquake excitation. The peak distribution of power spectral density curves are analyzed, then the formulas of structural mean squared displacement (MSD) and research parameters is derived based on random vibration theory. Then the relationship of the adjacent structural seismic response versus the research parameters was presented. The optimal value of the linking visco-elastic damper damping ratio and stiffness ratio are investigated. Finally, the seismic responses of example structures with or without connecting dampers are contrastively analyzed. The dependence of response mitigation effective on research parameters is highlighted. The results indicate fine earthquake-reduction effectiveness of dampers connecting adjacent structures. It is also shows that optimal parameters of damper cannot reduce the seismic responses of the primary structures connected to the best extent simultaneously. The damper parameters should be determined according to the best seismic mitigation effectiveness of the primary, auxiliary structure or the combined structure system.

scholarly journals Vibration control of steel frames with setback irregularities equipped with semi-active tuned mass dampers

2021 ◽  
Author(s):  
Seyed Amin Hosseini ◽  
Vahid Jahangiri ◽  
Ali Massumi
Keyword(s):  
Vibration Control ◽  
Control Systems ◽  
Structural Vibration ◽  
Base Shear ◽  
Tuned Mass Dampers ◽  
Steel Moment Resisting Frames ◽  
Irregular Structures ◽  
Story Drift ◽  
Moment Resisting ◽  
Control Devices

Abstract Vibration control of structures has been a focus of research worldwide. Although, several studies have examined the efficiency of semi-active tuned mass dampers (SATMDs) to control the seismic vibration of structures, only a few have focused on the influence of SATMDs on steel moment resisting frames in irregular structures having setbacks. In the current investigation, the use of SATMDs for the vibration control of structures with setbacks subjected to earthquake records has been evaluated. In order to assess the nonlinear seismic performance of buildings with setbacks, the inter-story drift ratio, story displacement, and base shear factor were examined as engineering demand parameters. The results reveal that the use of SATMDs reduced the seismic response of regular and irregular frames with setbacks. However, the use of these control devices requires more attention for structures with significant setbacks because, in some cases, the response of a structure with SATMDs can be greater than of an uncontrolled structure. The investigations also showed that placement of the control systems at the highest (top) level of the structure significantly reduced the structural vibration of both types of structure.

scholarly journals Сhoosing the Belt Conveyor Start Mode

2019 ◽  
pp. 54-59
Author(s):  
Vladimir P. Metelkov ◽  
Yakov L. Liberman
Keyword(s):  
Asynchronous Motor ◽  
Conveyor Belt ◽  
Tension Control ◽  
Dynamic Loads ◽  
Electric Drives ◽  
Start Up ◽  
High Tension ◽  
Control Devices ◽  
The Cost ◽  
The Magnetic Field

The paper is concerned with the problems associated with starting a long conveyor driven by an induction motor. We consider the dynamic loads in the conveyor belt during start-up, which cause slippage of the conveyor belt on the traction drum leading to its premature deterioration. The relevance of the topic is associated with the high cost of the conveyor belt reaching 60% of the cost of the entire conveyor and more. The aim of the work is to ascertain the possibilities of reducing the wear of the conveyor belt, for example, through the use of the possibilities provided by the system of the electric drive. The possibility of reducing the probability of the conveyor belt slippage by increasing the initial belt tension is noted. However, constant high tension also accelerates belt deterioration. To solve this problem, the use of automatic tension control devices is proposed, as well as the reduction of dynamic loads in the belt by using soft starters based on a thyristor voltage converter, which regulates the amplitude of voltage on the motor stator. The features of an asynchronous motor heating when starting with a constant speed of rotation of the magnetic field are discussed. The interrelation between the start-up duration and the motor stator winding heating with the dynamic loads occurring in the conveyor belt in start-up modes is considered. Modeling results obtained using the Simulink package are presented. Since long start-up modes of asynchronous electric drives based on thyristor voltage converters can lead to motor overheating, especially when the conveyor is restarted under full load and in hot climates, it is advisable to use automatic conveyor belt tension control devices during start-up modes thereby reducing premature belt deterioration together with a decrease in the conveyor motor heating.

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