Constant-ductility inelastic displacement, velocity and acceleration ratios for systems subjected to simple pulses

2020 ◽  
Vol 131 ◽  
pp. 106027 ◽  
Author(s):  
Foteini Konstandakopoulou ◽  
George Hatzigeorgiou
Keyword(s):  
Displacement Velocity ◽  
Inelastic Displacement

Inelastic response spectra of self-centering structures with the flag-shaped hysteretic response subjected to near-fault pulse-type ground motions

2021 ◽  
pp. 875529302110003
Author(s):  
Huihui Dong ◽  
Qiang Han ◽  
Xiuli Du ◽  
Shoushan Cheng ◽  
Haifang He
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Response Spectra ◽  
Displacement Velocity ◽  
Hysteretic Behavior ◽  
Hysteretic Model ◽  
Inelastic Response ◽  
Inelastic Displacement ◽  
Near Fault ◽  
Pulse Type

Many studies on the inelastic response spectra have mainly focused on structures with the conventional hysteretic behavior. However, for self-centering structures with the flag-shaped (FS) hysteretic behavior, the corresponding study is limited. The primary aim of this study is to investigate the inelastic response spectra of self-centering structures with FS hysteretic behavior subjected to the near-fault pulse-type ground motion. To this end, the smooth FS hysteretic model based on Bouc–Wen model is developed, and the characteristics of pulse-type ground motions are described in detail. It is found that the general features of inelastic response spectra of the FS model are sensitive to the acceleration-, velocity-, and displacement-sensitive spectral regions of the ground motion. The inelastic displacement, velocity, acceleration, and ductility factor spectra of the FS hysteretic model for pulse-type ground motions are much larger than those for ordinary ground motions, while the residual displacement spectra under the two types of ground motions are both very small due to its self-centering capacity. Moreover, the inelastic response spectra are affected by the ground motion characteristics and structural hysteresis behavior, especially the large pulse period and peak ground velocity (PGV) significantly increase the inelastic displacement, velocity, and acceleration spectra.

scholarly journals Displacement Demand for Nonlinear Static Analyses of Masonry Structures: Critical Review and Improved Formulations

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 118
Author(s):  
Gabriele Guerrini ◽  
Stylianos Kallioras ◽  
Stefano Bracchi ◽  
Francesco Graziotti ◽  
Andrea Penna
Keyword(s):  
Time History ◽  
Nonlinear Static Analysis ◽  
Equivalent Linearization ◽  
Eurocode 8 ◽  
Masonry Structures ◽  
Equivalent Viscous Damping ◽  
Inelastic Displacement ◽  
N2 Method ◽  
Nonlinear Static ◽  
Nonlinear Time History

This paper discusses different formulations for calculating earthquake-induced displacement demands to be associated with nonlinear static analysis procedures for the assessment of masonry structures. Focus is placed on systems with fundamental periods between 0.1 and 0.5 s, for which the inelastic displacement amplification is usually more pronounced. The accuracy of the predictive equations is assessed based on the results from nonlinear time-history analyses, carried out on single-degree-of-freedom oscillators with hysteretic force–displacement relationships representative of masonry structures. First, the study demonstrates some limitations of two established approaches based on the equivalent linearization concept: the capacity spectrum method of the Dutch guidelines NPR 9998-18, and its version outlined in FEMA 440, both of which overpredict maximum displacements. Two codified formulations relying on inelastic displacement spectra are also evaluated, namely the N2 method of Eurocode 8 and the displacement coefficient method of ASCE 41-17: the former proves to be significantly unconservative, while the latter is affected by excessive dispersion. A non-iterative procedure, using an equivalent linear system with calibrated optimal stiffness and equivalent viscous damping, is then proposed to overcome some of the problems identified earlier. A recently developed modified N2 formulation is shown to improve accuracy while limiting the dispersion of the predictions.

A video imaging method for time-dependent measurements of molecular mass transfer and biofilm dynamics in microchannels

MRS Advances ◽  
2016 ◽  
Vol 1 (29) ◽  
pp. 2099-2106 ◽  
Author(s):  
M. Parvinzadeh Gashti ◽  
M. Zarabadi ◽  
J. Greener
Keyword(s):  
Biomass Accumulation ◽  
Structural Heterogeneity ◽  
Displacement Velocity ◽  
Imaging Method ◽  
Shear Forces ◽  
Growth Environment ◽  
Biofilm Thickness ◽  
Loading Rates ◽  
Local Shear ◽  
Growth Approach

ABSTRACTThe biomass accumulation and movement of biofilms in a microchannel is monitored by optical microscopy. First, the average optical density of the biofilm is monitored in time as a measure of biofilm thickness and structural heterogeneity. These results are used as inputs to calculate changing flow velocities due to resulting excluded volume. Next the displacement velocity of moving biofilm segments was recorded in different places in the microchannel. Quantitative analysis by a particle tracking routine showed differences in displacement velocity near and far from the microchannel corner, which is believed to be related to the local shear forces which vary depending on the height of the biofilm segment and its position in the microchannel. The effect of changing biofilm thickness and different hydrodynamic environments in the microchannel are then discussed in terms of their effects on molecular loading rates. Finally, a demonstration of a flow-templated growth approach as a means to homogenize the growth environment.

The Method for Determining the Vibration-Damping Elements for the Mechanical System to Obtain the Desired Amplitude Value

2014 ◽  
Vol 657 ◽  
pp. 644-648 ◽  
Author(s):  
Andrzej Dymarek ◽  
Tomasz Dzitkowski
Keyword(s):  
Mechanical System ◽  
Dynamic Characteristics ◽  
Vibration Reduction ◽  
Mechanical Systems ◽  
Vibration Damping ◽  
Displacement Velocity ◽  
Synthesis Methods ◽  
Resonance Frequencies

The paper presents the use of synthesis methods to determine the parameters of passive vibration reduction in mechanical systems. Passive vibration reduction in a system is enabled by units called dampers whose values are determined on the basis of the method formulated and formalized by the authors. The essence of the method are, established at the beginning of a task, dynamic characteristics in the form of the resonance and anti-resonance frequencies, and amplitudes of displacement, velocity or acceleration of vibration.

Analysis of Errors in the Double Hooke Joint

1965 ◽  
Vol 87 (2) ◽  
pp. 251-257 ◽  
Author(s):  
T. C. Austin ◽  
J. Denavit ◽  
R. S. Hartenberg
Keyword(s):  
Angular Velocity ◽  
Velocity Ratio ◽  
Displacement Velocity ◽  
Matrix Methods ◽  
Input And Output ◽  
Manufacturing Errors ◽  
Kinematic Analyses ◽  
Dimensional Errors ◽  
Analytical Expressions ◽  
The Ideal

A double Hooke joint consists of two properly connected single Hooke joints for the purpose of transmitting rotation with a uniform angular velocity ratio. Previous kinematic analyses [1, 2, 3] have dealt with Hooke joints of perfect or ideal configuration, viz., in which pertinent axes intersect and are perpendicular. With real Hooke joints the manufacturing errors (which include tolerances) produce axes that do not intersect and are not perpendicular. The present analysis [4] investigates the effects of such departures from the ideal for the case of the double Hooke joint. It considers their effect on the mechanism’s movability, and studies their influence on the displacement, velocity, and acceleration relations between input and output shafts. The problem is solved by matrix methods: displacement relations are derived for the ideal double Hooke joint, after which the effects of small dimensional errors are considered as perturbations from the ideal values. The analytical expressions allow the variations in velocities and accelerations to be obtained by differentiation.

scholarly journals Inelastic displacement ratios for non-structural components in steel framed structures under forward-directivity near-fault strong-ground motion

2021 ◽  
Author(s):  
M. A. Bravo-Haro ◽  
J. R. Virreira ◽  
A. Y. Elghazouli
Keyword(s):  
Strong Ground Motion ◽  
Ground Motions ◽  
Structural Elements ◽  
Structural Components ◽  
Framed Structures ◽  
Inelastic Displacement ◽  
Near Fault ◽  
Forward Directivity ◽  
The Mean ◽  
Strong Ground

AbstractThis paper describes a detailed numerical investigation into the inelastic displacement ratios of non-structural components mounted within multi-storey steel framed buildings and subjected to ground motions with forward-directivity features which are typical of near-fault events. The study is carried out using detailed multi-degree-of-freedom models of 54 primary steel buildings with different structural characteristics. In conjunction with this, 80 secondary non-structural elements are modelled as single-degree-of-freedom systems and placed at every floor within the primary framed structures, then subsequently analysed through extensive dynamic analysis. The influence of ground motions with forward-directivity effects on the mean response of the inelastic displacement ratios of non-structural components are compared to the results obtained from a reference set of strong-ground motion records representing far-field events. It is shown that the mean demand under near-fault records can be over twice as large as that due to far-fault counterparts, particularly for non-structural components with periods of vibration lower than the fundamental period of the primary building. Based on the results, a prediction model for estimating the inelastic displacement ratios of non-structural components is calibrated for far-field records and near-fault records with directivity features. The model is valid for a wide range of secondary non-structural periods and primary building fundamental periods, as well as for various levels of inelasticity induced within the secondary non-structural elements.

Ground Motion Prediction Model for the Peak Inelastic Displacement of Single-Degree-of-Freedom Bilinear Systems

2018 ◽  
Vol 34 (3) ◽  
pp. 1177-1199 ◽  
Author(s):  
Pablo Heresi ◽  
Héctor Dávalos ◽  
Eduardo Miranda
Keyword(s):  
Prediction Model ◽  
Ground Motion ◽  
Degree Of Freedom ◽  
Motion Prediction ◽  
Ground Motion Prediction ◽  
Vibration Period ◽  
Single Degree Of Freedom ◽  
Inelastic Displacement ◽  
Single Degree ◽  
Proposed Model

This paper presents a ground motion prediction model (GMPM) for estimating medians and standard deviations of the random horizontal component of the peak inelastic displacement of 5% damped single-degree-of-freedom (SDOF) systems, with bilinear hysteretic behavior and 3% postelastic stiffness ratio, directly as a function of the earthquake magnitude and the distance to the source. The equations were developed using a mixed effects model, with 1,662 recorded ground motions from 63 seismic events. In the proposed model, the median is computed as a function of the vibration period and the normalized strength of the system, as well as the event magnitude and the Joyner-Boore distance to the source. The standard deviation of the model is computed as a function of the vibration period and the normalized strength of the system. The proposed model has the advantage of not requiring an auxiliary elastic GMPM to predict the median and dispersion of peak inelastic displacement.

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