Application of Supplemental Damping Characteristics to Response Spectrum Analyses of Nonproportionally Damped Multistory Asymmetric-Plan Buildings

2013 ◽  
Vol 29 (1) ◽  
pp. 207-232 ◽  
Author(s):  
Jui-Liang Lin ◽  
Keh-Chyuan Tsai
Keyword(s):  
Response Spectrum ◽  
Response Spectra ◽  
Vibration Modes ◽  
Numerical Examples ◽  
System Parameters ◽  
Damping Characteristics ◽  
Supplemental Damping ◽  
Story Building

For practicing engineers, knowledge of the characteristics of supplemental damping in buildings is essential to understand the resultant effects of added damping. Characterizing the overall system parameters representing the amount and the plan-wise distribution of the supplemental damping in a single-story asymmetrical building is straightforward. However, this becomes a difficult task for multistory asymmetrical buildings. For this reason, this paper first develops the effective one-story building (EOSB), which retains the characteristics of the two dominant vibration modes of the original nonproportionally damped multistory asymmetrical building. By using the EOSB, it becomes convenient to characterize the supplemental damping in the original multistory asymmetrical building. The effectiveness of this approach is verified by using three numerical examples, which include one one-story, three eight-story, and one 20-story asymmetrical buildings. Next, the relationships between the roof displacements of the original building and those of the EOSB are established. This enables the application of the response spectra constructed from the EOSBs to estimate the peak roof displacements of the original multistory asymmetrical building.

scholarly journals A study on the vibration dissipation mechanism of the rotating blade with dovetail joint

2021 ◽  
pp. 146134842098533
Author(s):  
Chaofeng Li ◽  
Zengchuang Shen ◽  
Zilin Chen ◽  
Houxin She
Keyword(s):  
Dry Friction ◽  
Vibration Reduction ◽  
Friction Model ◽  
Rotating Speed ◽  
System Parameters ◽  
Tangential Stiffness ◽  
Damping Characteristics ◽  
Rotating Blade ◽  
Spatial Beam ◽  
Dissipation Mechanism

The vibration dissipation mechanism of the rotating blade with a dovetail joint is studied in this paper. Dry friction damping plays an indispensable role in the direction of vibration reduction. The vibration level is reduced by consuming the total energy of the turbine blade with the dry friction device on the blade-root in the paper. The mechanism of the vibration reduction is revealed by the variation of the friction force and the energy dissipation ratio of dry friction. In this paper, the flexible blade with a dovetail interface feature is discretized by using the spatial beam element based on the finite element theory. Then the classical Coulomb-spring friction model is introduced to obtain the dry friction model on the contact interfaces of the tenon-mortise structure. What is more, the effects of the system parameters (such as the rotating speed, the friction coefficient, the installation angle of the tenon) and the excitation level on blade damping characteristics are discussed, respectively. The results show that the variation of the system parameters leads to a significant change of damping characteristics of the blade. The variation of the tangential stiffness and the position of the external excitation will affect the nonlinear characteristics and vibration damping characteristics.

scholarly journals A Multi-Objective Ground Motion Selection Approach Matching the Acceleration and Displacement Response Spectra

2018 ◽  
Vol 10 (12) ◽  
pp. 4659 ◽  
Author(s):  
Yabin Chen ◽  
Longjun Xu ◽  
Xingji Zhu ◽  
Hao Liu
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Structural Response ◽  
Response Spectra ◽  
Computationally Efficient ◽  
Ground Motion Selection ◽  
Displacement Response ◽  
Rc Frames ◽  
Selection Approach ◽  
Displacement Response Spectra

For seismic resilience-based design (RBD), a selection of recorded time histories for dynamic structural analysis is usually required. In order to make individual structures and communities regain their target functions as promptly as possible, uncertainty of the structural response estimates is in great need of reduction. The ground motion (GM) selection based on a single target response spectrum, such as acceleration or displacement response spectrum, would bias structural response estimates leading significant uncertainty, even though response spectrum variance is taken into account. In addition, resilience of an individual structure is not governed by its own performance, but depends severely on the performance of other systems in the same community. Thus, evaluation of resilience of a community using records matching target spectrum at whole periods would be reasonable because the fundamental periods of systems in the community may be varied. This paper presents a GM selection approach based on a probabilistic framework to find an optimal set of records to match multiple target spectra, including acceleration and displacement response spectra. Two major steps are included in that framework. Generation of multiple sub-spectra from target displacement response spectrum for selecting sets of GMs was proposed as the first step. Likewise, the process as genetic algorithm (GA), evolvement of individuals previously generated, is the second step, rather than using crossover and mutation techniques. A novel technique improving the match between acceleration response spectra of samples and targets is proposed as the second evolvement step. It is proved computationally efficient for the proposed algorithm by comparing with two developed GM selection algorithms. Finally, the proposed algorithm is applied to select GM records according to seismic codes for analysis of four archetype reinforced concrete (RC) frames aiming to evaluate the influence of GM selection considering two design response spectra on structural responses. The implications of design response spectra especially the displacement response spectrum and GM selection algorithm are summarized.

scholarly journals Hopf bifurcation for an SIR model with age structure

2021 ◽  
Author(s):  
HUI CAO ◽  
Dongxue Yan ◽  
Xiaxia Xu
Keyword(s):  
Cauchy Problem ◽  
Hopf Bifurcation ◽  
Bifurcation Analysis ◽  
Age Structure ◽  
Equilibrium Points ◽  
Sir Model ◽  
Numerical Examples ◽  
System Parameters ◽  
Stability And Instability ◽  
Densely Defined

This paper deals with an SIR model with age structure of infected individuals. We formulate the model as an abstract non-densely defined Cauchy problem and derive the conditions for the existence of all the feasible equilibrium points of the system. The criteria for both stability and instability involving system parameters are obtained. Bifurcation analysis indicates that the system with age structure exhibits Hopf bifurcation which is the main result of this paper. Finally, some numerical examples are provided to illustrate our obtained results.

scholarly journals Preliminary results of ground-motion characteristics

2012 ◽  
Vol 55 (4) ◽  
Author(s):  
Francesca Bozzoni ◽  
Carlo Giovanni Lai ◽  
Laura Scandella
Keyword(s):  
Ground Motion ◽  
Site Response ◽  
Response Spectrum ◽  
Field Tests ◽  
Response Spectra ◽  
Ground Acceleration ◽  
Preliminary Results ◽  
Emilia Earthquake ◽  
Particle Orbit ◽  
2012 Emilia Earthquake

The preliminary results are presented herein for the engineering applications of the characteristics of the ground motion induced by the May 20, 2012, Emilia earthquake. Shake maps are computed to provide estimates of the spatial distribution of the induced ground motion. The signals recorded at the Mirandola (MRN) station, the closest to the epicenter, have been processed to obtain acceleration, velocity and displacement response spectra. Ground-motion parameters from the MRN recordings are compared with the corresponding estimates from recent ground-motion prediction equations, and with the spectra prescribed by the current Italian Building Code for different return periods. The records from the MRN station are used to plot the particle orbit (hodogram) described by the waveform. The availability of results from geotechnical field tests that were performed at a few sites in the Municipality of Mirandola prior to this earthquake of May 2012 has allowed preliminary assessment of the ground response. The amplification effects at Mirandola are estimated using fully stochastic site-response analyses. The seismic input comprises seven actual records that are compatible with the Italian code-based spectrum that refers to a 475-year return period. The computed acceleration response spectrum and the associated dispersion are compared to the spectra calculated from the recordings of the MRN station. Good agreement is obtained for periods up to 1 s, especially for the peak ground acceleration. For the other periods, the spectral acceleration of the MRN recordings exceeds that of the computed spectra.<br />

scholarly journals A Literature Review on Seismic Response of Floating Column Building

2021 ◽  
Vol 9 (12) ◽  
pp. 68-72
Author(s):  
Deepak Jain
Keyword(s):  
Literature Review ◽  
Seismic Response ◽  
Spectrum Analysis ◽  
Response Spectrum ◽  
Seismic Loads ◽  
Seismic Zone ◽  
Response Spectrum Analysis ◽  
Promising Solution ◽  
Story Building ◽  
Shape And Size

Abstract: Floating column building is a new fascination for engineers. As floating column buildings provides more space and good aesthetics to the building. But have high structural challenges, when a floating column is provided in a multi-story building in a high seismic zone. This paper reviews several studies conducted on the floating column building and its behavior under seismic loads. This paper studies that floating column building are vulnerable to the high seismic zones. The risk of damage also depends on the shape and size of the buildings.The ductile detailing of the joints is the promising solution for immediate failure of such buildings. Keywords: Floating Column, Response spectrum analysis. Vulnerable, damage, multi-story

Response spectral matching of horizontal ground motion components to an orientation-independent spectrum (RotDnn)

2020 ◽  
pp. 875529302097098
Author(s):  
Luis A Montejo
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Time History ◽  
Response Spectra ◽  
Major Axis ◽  
Component Level ◽  
Nonlinear Characteristics ◽  
Target Spectrum ◽  
Horizontal Ground Motion ◽  
Median Spectrum

This article presents a methodology to spectrally match two horizontal ground motion components to an orientation-independent target spectrum (RotDnn). The algorithm is based on the continuous wavelet transform decomposition and iterative manipulation of the two horizontal components of a seed record. The numerical examples presented follow current ASCE/SEI 7 specifications and therefore maximum-direction spectra (RotD100) are used as target for the match. However, the proposed methodology can be used to match other RotDnn spectra, like the median spectrum (RotD50). It is shown that with the proposed methodology the resulting RotDnn from the modified horizontal components closely match the smooth target RotDnn spectrum, while the response spectrum for each horizontal component continue to exhibit a realistic jagged behavior. The response spectra variability at the component level within suites of spectrally matched motions was found to be of the same order than the variability measured in suites composed of amplitude scaled records. Moreover, the spectrally matched records generated preserved most of the characteristics of the seed records, including the nonlinear characteristics of the time history traces and the period-dependent major axis orientations.

Analytical Determination of Shock Response Spectra for an Impulse-Loaded Proportionally Damped System

Volume 1 ◽  
2004 ◽  
Author(s):  
R. David Hampton ◽  
Nathan S. Wiedenman ◽  
Ting H. Li
Keyword(s):  
Transient Response ◽  
Shock Loading ◽  
Response Spectrum ◽  
Response Spectra ◽  
Analytical Determination ◽  
System Response ◽  
Mechanical Shock ◽  
Shock Response ◽  
Mass Spring ◽  
The Impact

Many military systems must be capable of sustained operation in the face of mechanical shocks due to projectile or other impacts. The most widely used method of quantifying a system’s vibratory transient response to shock loading is called the shock response spectrum (SRS). The system response for which the SRS is to be determined can be due, physically, either to a collocated or to a noncollocated shock loading. Taking into account both possibilities, one can define the SRS as follows: the SRS presents graphically the maximum transient response (output) of an imaginary ideal mass-spring-damper system at one point on a flexible structure, to a particular mechanical shock (input) applied to an arbitrary (perhaps noncollocated) point on the structure, as a function of the natural frequency of the imaginary mass-spring-damper system. For a response point sufficiently distant from the impact area, many Army platforms (such as vehicles) can be accurately treated as linear systems with proportional damping. In such cases the output due to an impulsive mechanical-shock input can be decomposed into exponentially decaying sinusoidal components, using normal-mode orthogonalization. Given a shock-induced loading comprising such components, this paper provides analytical expressions for the various common SRS forms. The analytical approach to SRS-determination can serve as a verification of, or an alternative to, the numerical approaches in current use for such systems. No numerical convolution is required, because the convolution integrals have already been accomplished analytically (and exactly), with the results incorporated into the algebraic expressions for the respective SRS forms.

scholarly journals Design Earthquake Response Spectrum Affected by Shallow Soil Deposit

2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Dong-Kwan Kim ◽  
Hong-Gun Park ◽  
Chang-Guk Sun
Keyword(s):  
Soil Depth ◽  
Site Response ◽  
Response Spectrum ◽  
Soft Soil ◽  
Response Spectra ◽  
Earthquake Response ◽  
Ground Acceleration ◽  
Site Class ◽  
Shallow Soil ◽  
Short Period

Site response analyses were performed to investigate the earthquake response of structures with shallow soil depth conditions in Korea. The analysis parameters included the properties of soft soil deposits at 487 sites, input earthquake accelerations, and peak ground-acceleration levels. The response spectra resulting from numerical analyses were compared with the design response spectra (DRS) specified in the 2015 International Building Code. The results showed that the earthquake motion of shallow soft soil was significantly different from that of deep soft soil, which was the basis of the IBC DRS. The responses of the structures were amplified when their dynamic periods were close to those of the site. In the case of sites with dynamic periods less than 0.4 s, the spectral accelerations of short-period structures were greater than those of the DRS corresponding to the site class specified in IBC 2015. On the basis of these results, a new form of DRS and soil factors are proposed.

Study on the Characters of Seismic Response Spectra Based on China Financial Information Mansion

2014 ◽  
Vol 580-583 ◽  
pp. 1729-1733
Author(s):  
Ming Li ◽  
Yuan Qing Wang ◽  
Wei Tao ◽  
Bin Wang ◽  
Qing Xian Yu ◽  
...  
Keyword(s):  
Seismic Response ◽  
Response Spectrum ◽  
Response Spectra ◽  
Financial Information ◽  
Amplification Coefficient ◽  
Response Analysis ◽  
Magnification Factor ◽  
Characteristic Period ◽  
Seismic Coefficient ◽  
Dynamic Magnification Factor

Rare study is done on floor response spectrum of super-high rise building, but it is an important condition for the seismic response analysis of floor subsidiary structure. Therefore, based on the early calculation model of China Financial Information Mansion, the floor response spectrum is calculated under different input ground motion. The floor and ground response spectrum is compared with each other from the seismic coefficient, dynamic amplification coefficient, characteristic period and the form of response spectrum. The results shows that: the floor seismic coefficient and the magnification coefficient are greater or smaller than the ground ones, the biggest difference of which is nearly 1 times; all the floor character period are greater than the ground ones, the biggest difference of which is over 60%; there are obvious differences between the floor and ground dynamic magnification factor spectra form under some conditions, of which the second peak of the former one is probably very large, even near to the peak of the first one, while the latter has no such phenomenon. Therefore, during the process of calculating the seismic response of floor subsidiary structure, it is necessary to consider the change of floor seismic coefficient, dynamic magnification factor, characteristic period and spectra form based on the main structure.

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