scholarly journals Inelastic Responses of Two-Way Asymmetric-Plan Structures under Bidirectional Ground Excitations—Part II: Response Spectra

2012 ◽  
Vol 28 (1) ◽  
pp. 141-157 ◽  
Author(s):  
Jui-Liang Lin ◽  
Wen-Chia Yang ◽  
Keh-Chyuan Tsai
Keyword(s):  
Vibration Mode ◽  
Response Spectra ◽  
Companion Paper ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Ductility Demand ◽  
Inelastic Responses ◽  
Constant Strength ◽  
Three Degree Of Freedom ◽  
Modal Systems

Based on the studies in the companion paper, this paper presents the inelastic response spectra for asymmetrical structures (SAS) under bidirectional ground excitations. Firstly, the constant-strength SAS were constructed and compared with the corresponding conventional constant-strength response spectra. It was found that the modal ductility demands of an asymmetric-plan structure could be significantly overestimated from the conventional constant-strength response spectra as the nonlinear “modal” rotation and translations may not be proportional. Furthermore, the translation-rotation interaction effect is not considered in the conventional constant-strength response spectra. Secondly, the influences of the three-degree-of-freedom (3DOF) modal parameters on the ductility demand were extensively studied. Thirdly, the normalized peak edge translation spectra were also investigated. It was found that the normalized peak edge translation resulting from a single vibration mode may be overestimated twofold by using the single-degree-of-freedom (SDOF) modal systems.

scholarly journals Inelastic Responses of Two-Way Asymmetric-Plan Structures under Bidirectional Ground Excitations—Part I: Modal Parameters

2012 ◽  
Vol 28 (1) ◽  
pp. 105-139 ◽  
Author(s):  
Jui-Liang Lin ◽  
Keh-Chyuan Tsai ◽  
Wen-Chia Yang
Keyword(s):  
Vibration Mode ◽  
Response Spectra ◽  
Modal Parameters ◽  
Building Structure ◽  
Elastic Parameters ◽  
Modal System ◽  
Inelastic Responses ◽  
Three Degree Of Freedom ◽  
Modal Systems ◽  
Variation Trends

It has been found that any one vibration “mode” of an inelastic multistory two-way asymmetrical building structure can be represented by a three-degree-of-freedom (3DOF) modal system representing two modal translations and one modal rotation. This study introduces the inelastic response spectra constructed from the inelastic 3DOF modal systems, which is specifically useful for multistory two-way asymmetric-plan buildings subjected to bidirectional ground excitations. These spectra for asymmetrical structures (SAS) provide the three-component inelastic peak modal responses of multistory two-way asymmetric-plan buildings subjected to bidirectional ground excitations. In order to construct the SAS, the independent elastic parameters of the 3DOF modal systems were identified and the inelastic 3DOF modal parameters versus the strength ratio relationships were established. The parametric study of the 3DOF modal parameters showed the ranges and the variation trends of these parameters. Two example buildings are analyzed to verify the effectiveness of the above-mentioned investigations.

Effects of human-induced load models on tuned mass damper in reducing floor vibration

2019 ◽  
Vol 22 (11) ◽  
pp. 2449-2463
Author(s):  
Jun Chen ◽  
Ziping Han ◽  
Ruotian Xu
Keyword(s):  
Response Spectra ◽  
Tuned Mass Damper ◽  
Design Guidelines ◽  
Degree Of Freedom ◽  
Dynamic Responses ◽  
Single Degree Of Freedom ◽  
Load Model ◽  
Load Models ◽  
Single Degree ◽  
Mass Damper

Dozens of human-induced load models for individual walking and jumping have been proposed in the past decades by researchers and are recommended in various design guidelines. These models differ from each other in terms of function orders, coefficients, and phase angles. When designing structures subjected to human-induced loads, in many cases, a load model is subjectively selected by the design engineer. The effects of different models on prediction of structural responses and efficiency of vibration control devices such as a tuned mass damper, however, are not clear. This article investigates the influence of human-induced load models on performance of tuned mass damper in reducing floor vibrations. Extensive numerical simulations were conducted on a single-degree-of-freedom system with one tuned mass damper, whose dynamic responses to six walking and four jumping load models were calculated and compared. The results show a maximum three times difference in the acceleration responses among all load models. Acceleration response spectra of the single-degree-of-freedom system with and without a tuned mass damper were also computed and the response reduction coefficients were determined accordingly. Comparison shows that the reduction coefficient curves have nearly the same tendency for different load models and a tuned mass damper with 5% mass ratio is able to achieve 50%–75% response reduction when the structure’s natural frequency is in multiples of the walking or jumping frequency. All the results indicate that a proper load model is crucial for structural response calculation and consequently the design of tuned mass damper device.

Design and Modeling of a Three-Degree-of-Freedom Articulating Robotic Microsurgical Forceps for Trans-Oral Laser Microsurgery

2019 ◽  
Vol 13 (2) ◽  
Author(s):  
Manish Chauhan ◽  
Nikhil Deshpande ◽  
Darwin G. Caldwell ◽  
Leonardo S. Mattos
Keyword(s):  
Degree Of Freedom ◽  
Preliminary Evaluation ◽  
Laser Microsurgery ◽  
Single Degree Of Freedom ◽  
Control Interface ◽  
Tissue Manipulation ◽  
Manual Handling ◽  
Three Degree Of Freedom ◽  
Tool Rotation ◽  
Poor Efficacy

Trans-oral laser microsurgery (TLM) is a surgical procedure for removing malignancies (e.g., cysts, polyps, tumors) of the laryngeal region through laser ablation. Intraoperative microsurgical forceps (i.e., microforceps) are used for tissue manipulation. The microforceps are rigid, single degree-of-freedom (DOF) devices (open–close) with precurved jaws to access different parts of the curved cylindrical laryngeal region. These microforceps are manually handled and are subject to hand tremors, poor reachability, and nonergonomic use, resulting in poor efficacy and efficiency in the surgery. A novel 3DOF motorized microforceps device is presented here, integrated with a 6DOF serial robotic manipulator. The device, referred to as RMF-3, offers three motorized DOFs: (i) open–close forceps jaw; (ii) tool rotation; and (iii) tool-tip articulation. It is designed to be compliant with TLM spatial constraints. The manual handling is replaced by tele-operation device, the omega.7. The design of the RMF-3 is characterized through theoretical and experimental analysis. The device shows a maximum articulation of 38 deg and tool rotation of 100 deg. Its performance is further evaluated through user trials using the ring-in-loop setup. The user trials demonstrate benefits of the 3DOF workspace of the device along with its teleoperation control. RMF-3 offers an improved workspace and reachability within the laryngeal region. Surgeons, in their preliminary evaluation of the device, appreciated the ability to articulate the tip, along with rotation, for hard-to-reach parts of the surgical site. RMF-3 offers an ergonomic robotic teleoperation control interface which overcomes hand tremors and extreme wrist excursion which leads to surgeon pain and discomfort.

Effect of the orientation of records on displacement ductility demand

2012 ◽  
Vol 39 (4) ◽  
pp. 362-373 ◽  
Author(s):  
A.D. García-Soto ◽  
H.P. Hong ◽  
R. Gómez
Keyword(s):  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Ductility Demand ◽  
Displacement Ductility ◽  
Single Degree ◽  
Perfectly Plastic ◽  
Principal Axes ◽  
Hazard And Risk ◽  
Elastic Perfectly Plastic ◽  
Pseudo Spectral

Effects of the ground motion record orientation on the estimated pseudo-spectral acceleration (PSA) have been investigated and reported in the literature; the statistics of the PSA along the major and minor principal axes differ from that for a random orientation. This is true for California as well as for Mexican records. However, a statistical assessment of the effect of record orientation on the displacement ductility demand is lacking. Such an assessment could be important for gaining confidence in and understanding of using the ductility demand rules for seismic hazard and risk evaluations. The statistical analyses of the effect of orientation on the estimated displacement ductility demand for elastic-perfectly-plastic and bilinear hysteretic (single degree of freedom) systems is carried out in the present study using sets of records from Mexican inslab and interplate earthquakes, and California earthquakes. Based on the obtained statistics, it is suggested that the consideration that the ductility demand is independent of the orientation of the records can be adequate, especially for Tn greater than 0.3 s and elastic-perfectly-plastic hysteretic single degree of freedom systems.

Statistical Analyses of Response Spectra on Medium-Stiff Soil Site

2011 ◽  
Vol 90-93 ◽  
pp. 1549-1554
Author(s):  
Wen Feng Liu ◽  
Xue Zhong Chen ◽  
Jie Ying Sui
Keyword(s):  
Goodness Of Fit ◽  
Probability Distributions ◽  
Response Spectra ◽  
Statistical Analyses ◽  
Statistical Average ◽  
Goodness Of Fit Test ◽  
Ductility Demand ◽  
Inelastic Responses ◽  
Soil Site ◽  
Stiff Soil

The analyses on the statistical response spectra have an important role in determining the earthquake demand. Elastic and inelastic spectra on acceleration of the 205 records on medium-stiff soil site for SDOF systems are presented in statistical analyses. The empirical probability distributions of the spectral values are derived according to the Kolmogorov-Smirnov (KS) goodness-of-fit test. The formula for statistical average spectra of the ground motion ensemble are recommended, which are valuable for current research and code revisal. The results show that the statistical averaged elastic α spectra fits well to the design spectra prescribed in Chinese code when the period is smaller than 2s. The inelastic responses decrease with the increase of ductility demand μ when μ<4. The coefficients of variance of the elastic and inelastic spectra are still large and the dispersion cannot be ignored. The probabilistic distribution of the spectra value on acceleration is validated as the lognormal distributions. The proposed formulas give a good fit to the statistical average values.

Instabilities Arising From the Frictional Interaction of a Pin-Disk System Resulting in Noise Generation

1976 ◽  
Vol 98 (1) ◽  
pp. 81-86 ◽  
Author(s):  
S. W. E. Earles ◽  
C. K. Lee
Keyword(s):  
Angular Speed ◽  
Degree Of Freedom ◽  
Noise Generation ◽  
Disk System ◽  
Single Degree Of Freedom ◽  
Disk Brake ◽  
Thin Steel ◽  
Three Degree Of Freedom ◽  
Squeal Noise ◽  
Experimental Rig

A steel pin, supported on a flexible cantilever, is pressed against a thin steel disk which rotates at a uniform angular speed. The orientation of the pin’s central axis to the plane of the disk, the bending and torsional stiffnesses of the pin support, the stiffness of the disk, and the line of action of the resultant interactive force are all shown to affect the self-induced coupled frequencies and modes generated. The analysis of the experimental arrangement in terms of a three-degree-of-freedom pin subsystem and a single-degree-of-freedom disk element suggests that the system is unstable for certain combinations of the variables. The instabilities are shown to belong to a class of “geometrically induced” or “kinematic constraint” instability. The region of squeal-noise generation within the experimental rig is shown to correspond to the oscillatory unstable region predicted theoretically. The noise generated is similar to disk-brake squeal, and so the work furthers the understanding of this practical problem.

Assessment of ductility demand and reliability of bilinear single-degree-of-freedom systems under earthquake loading

2007 ◽  
Vol 34 (12) ◽  
pp. 1606-1615 ◽  
Author(s):  
H. P. Hong ◽  
P. Hong
Keyword(s):  
Coefficient Of Variation ◽  
Degree Of Freedom ◽  
Initial Stiffness ◽  
Single Degree Of Freedom ◽  
Ductility Demand ◽  
Single Degree ◽  
Code Calibration ◽  
Probabilistic Characterization ◽  
The Mean ◽  
Ground Motion Records

Probabilistic assessments of the ductility demand and reliability analysis were carried out for hysteretic bilinear single-degree-of-freedom (SDOF) systems. The assessment considered a set of strong ground motion records, and focused on evaluating the mean and coefficient of variation of the ductility demand for a given normalized yield strength. Results indicated that the ductility demand could be modeled as a Frechet (extreme value type II) variate. Based on the obtained results, empirical equations were provided to predict the mean ductility demand for hysteretic bilinear SDOF systems considering different natural vibration periods, damping ratios, and post-yield stiffness to initial stiffness ratios. Numerical results showed that the coefficient of variation of the ductility demand can go as high as one, depending on the characteristics of the structure. Also, a simple approach was given to estimate the probabilities of incipient damage and incipient collapse using the developed probabilistic characterization of the ductility demand. This approach, which could be suitable for design code calibration analysis, is illustrated numerically in this study.

Vibration of Satellite Subsystem During Orbiter Lift-Off

1993 ◽  
Vol 8 (3) ◽  
pp. 167-176 ◽  
Author(s):  
Gina Lee-Glauser ◽  
Goodarz Ahmadi
Keyword(s):  
Response Spectra ◽  
Degree Of Freedom ◽  
Mass Ratio ◽  
Acceleration Response ◽  
Single Degree Of Freedom ◽  
Lump Parameter Model ◽  
Single Degree ◽  
Acceleration Response Spectra ◽  
Lift Off ◽  
Sinusoidal Excitation

Vibrations of a satellite and one of its sensitive subsystems during orbiter lift-off are studied. A single degree-of-freedom representation of the subsystem and a five degree-of-freedom lump parameter model of the satellite are considered. Deflection and acceleration response spectra of the satellite and its subsystem subject to sinusoidal excitation and the STS - 41 lift-off accelerations are evaluated. The significance of the subsystem and primary satellite interaction is investigated. The effect of mass ratio and damping coeficient of the subsystem on the peak deflection and acceleration response spectra of the satellite and its subsystem are examined.

Energy Transfer and Dissipation in a Three-Degree-of-Freedom System With Stribeck Friction

2005 ◽  
Author(s):  
Nguyen Do ◽  
Aldo A. Ferri
Keyword(s):  
Energy Transfer ◽  
Low Frequency ◽  
Friction Model ◽  
Degree Of Freedom ◽  
Simulation Studies ◽  
Transfer Energy ◽  
Interconnected System ◽  
Single Degree Of Freedom ◽  
Low Frequency Motion ◽  
Three Degree Of Freedom

Friction at connecting joints is a key mechanism by which passive damping occurs in built-up structures. This paper explores the ability of friction to transfer energy between subsystems of an interconnected system. Two single-degree-of-freedom (SDOF) systems are used to represent separate subsystems and a third mass is used to represent the connecting joint. A Stribeck friction model is used to represent the resistive force acting on this coupling mass. Through numerical simulation studies, the influence of the subsystem dynamics on the overall energy dissipation levels is investigated. In particular, it is seen that favorable tuning conditions exist that result in a “pumping” of energy from the low-frequency motion of one subsystem to the higher-frequency motion of the other subsystem. It is also seen that one-way energy transfer can occur in such a system due to the eventual joint lock-up that can occur when the connecting mass sticks.

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