An empirical model for the mean period (Tm) of ground motions using the NGA-West2 database

2017 ◽  
Vol 15 (7) ◽  
pp. 2673-2693 ◽  
Author(s):  
Wenqi Du
Keyword(s):  
Empirical Model ◽  
Ground Motions ◽  
The Mean

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.

Inelastic Displacement Spectra and Its Utilization of DDB Design for Seismic Isolated Bridges Subjected to Near-Fault Pulse-Like Ground Motions

2019 ◽  
Vol 35 (3) ◽  
pp. 1109-1140 ◽  
Author(s):  
Yi-feng Wu ◽  
Hao Wang ◽  
Jian Li ◽  
Ben Sha ◽  
Ai-qun Li
Keyword(s):  
Design Method ◽  
Ground Motions ◽  
Single Degree Of Freedom ◽  
Sdof System ◽  
Inelastic Displacement ◽  
Displacement Spectra ◽  
Near Fault ◽  
The Mean ◽  
Displacement Based ◽  
Isolated Bridges

A variety of research has focused on the inelastic displacement demand of a single degree of freedom (SDOF) system when subjected to near-fault pulse-like ground motions, in which the concerned ductility, μ, is typically lower than ten for normal structures. However, for seismic isolated structures that are more prone to large displacement, the corresponding research is limited. The purpose of this paper is to investigate the inelastic displacement spectra of an SDOF system with μ ranging from 5 to 70 and further proposes a direct displacement-based (DDB) design method for seismic isolated bridges. More concretely, a pool of near-fault pulse-like records is assembled, the mean C μ as a function of T/ T p is developed, and the influences of the ductility, μ, and the post-to-pre-yield ratio, α, on C μ are carefully investigated. Then the corresponding inelastic displacement spectra, S d, are obtained, and a comprehensive piecewise expression is proposed to fit S d. After that, the utilization of the spectra for the DDB design of a three-span seismic isolated continuous bridge is performed, and the principal of simplifying the bridge to an SDOF system is carefully explained and verified.

Fretting Wear of Heat Exchanger Tubes—Part I: Experiments

1979 ◽  
Vol 101 (4) ◽  
pp. 625-629 ◽  
Author(s):  
R. D. Blevins
Keyword(s):  
Heat Exchanger ◽  
Empirical Model ◽  
Room Temperature ◽  
Fretting Wear ◽  
Support Plate ◽  
Air Atmosphere ◽  
The Mean

The results of a series of measurements made on the fretting wear of heat exchanger tubes and support plates at room temperature in a nitrogen/air atmosphere are presented. The fretting wear is shown to be a function of the amplitude and frequency of tube vibration as well as the gap between the tube and the support plate and the mean load supported by the tube. An empirical model is developed in Part II for predicting the fretting wear.

scholarly journals Multi-criteria validation of artificial neural network rainfall-runoff modeling

2009 ◽  
Vol 13 (3) ◽  
pp. 411-421 ◽  
Author(s):  
R. Modarres
Keyword(s):  
Regression Model ◽  
Empirical Model ◽  
Rainfall Runoff ◽  
Runoff Modeling ◽  
Mean And Variance ◽  
High Flows ◽  
The Mean ◽  
Artificial Neural ◽  
Global Statistics ◽  
Non Parametric

Abstract. In this study we propose a comprehensive multi-criteria validation test for rainfall-runoff modeling by artificial neural networks. This study applies 17 global statistics and 3 additional non-parametric tests to evaluate the ANNs. The weakness of global statistics for validation of ANN is demonstrated by rainfall-runoff modeling of the Plasjan Basin in the western region of the Zayandehrud watershed, Iran. Although the global statistics showed that the multi layer perceptron with 4 hidden layers (MLP4) is the best ANN for the basin comparing with other MLP networks and empirical regression model, the non-parametric tests illustrate that neither the ANNs nor the regression model are able to reproduce the probability distribution of observed runoff in validation phase. However, the MLP4 network is the best network to reproduce the mean and variance of the observed runoff based on non-parametric tests. The performance of ANNs and empirical model was also demonstrated for low, medium and high flows. Although the MLP4 network gives the best performance among ANNs for low, medium and high flows based on different statistics, the empirical model shows better results. However, none of the models is able to simulate the frequency distribution of low, medium and high flows according to non-parametric tests. This study illustrates that the modelers should select appropriate and relevant evaluation measures from the set of existing metrics based on the particular requirements of each individual applications.

scholarly journals Firn Densification: An Empirical Model

1980 ◽  
Vol 25 (93) ◽  
pp. 373-385 ◽  
Author(s):  
Michael M. Herron ◽  
Chester C. Langway
Keyword(s):  
Empirical Model ◽  
Accumulation Rate ◽  
Rate Equations ◽  
Constant Density ◽  
Square Root ◽  
Accumulation Rates ◽  
Densification Rate ◽  
Second Stage ◽  
The Mean ◽  
Two Stages

AbstractAn empirical model of firn densification from the surface to the zone of pore close-off has been constructed. Fundamental rate equations have been derived for the first two stages of densification. In the first stage, for densities less than 0.55 Mg m−3, the densification rate is proportional to the mean annual accumulation times the term (ρi − ρ), where ρ is the density of the snow and ρi is the density of pure ice. The densification rate in the second stage, where 0.55 Mg m −3 < ρ < 0.8 Mg m−3, is proportional to the square root of the accumulation rate and to (ρi− ρ). Depth–density and depth–age calculations from this model are compared with observation. Model accumulation rates are within about 20% of values obtained by other techniques. It is suggested that depth intervals of constant density in some Antarctic cores may represent a synchronous event in the 1880 ’s when ten times the normal accumulation fell within a year or two.

scholarly journals A MODIFIED EMPIRICAL MODEL FOR ESTIMATING THE WETTED ZONE DIMENSIONS UNDER DRIP IRRIGATION

2015 ◽  
Vol 76 (15) ◽  
Author(s):  
Ahmed A. M. Al-Ogaidi ◽  
Aimrun Wayayok ◽  
Md Rowshon Kamal ◽  
Ahmed Fikri Abdullah
Keyword(s):  
Empirical Model ◽  
Drip Irrigation ◽  
Irrigation System ◽  
Model Performance ◽  
Coefficient Of Determination ◽  
Irrigation Systems ◽  
Modified Model ◽  
Model Efficiency ◽  
The Mean ◽  
Statistical Criteria

Drip irrigation system has become one of the most common irrigation systems especially in arid and semi-arid regions due to its advantages in saving water. One of the most essential considerations in designing these systems is the dimensions of the wetted soil volume under emitters. These dimensions are significant in choosing the proper emitter spacing along the laterals and the suitable distance between laterals. In this study, a modified empirical equations for estimating the horizontal and vertical extend of the wetted zone under surface emitters were suggested. Data from published papers includes different conditions of soil properties and emitter discharge were used in deriving the empirical model using the nonlinear regression. The developed model has high value for coefficient of determination, R2. The results from the developed model were compared with results of other empirical models derived by other researchers. Some statistical criteria were used to evaluate the model performance which are the mean error ME, root mean square error RMSE, and model efficiency EF. The results revealed that the modified model showed good performance in predicting the wetted zone dimensions and it can be used in design and management of drip irrigation systems. 

scholarly journals An empirical model of optical and radiative characteristics of the tropospheric aerosol over West Siberia in summer

2012 ◽  
Vol 5 (1) ◽  
pp. 137-161
Author(s):  
M. V. Panchenko ◽  
T. B. Zhuravleva ◽  
S. A. Terpugova ◽  
V. V. Polkin ◽  
V. S. Kozlov
Keyword(s):  
Empirical Model ◽  
West Siberia ◽  
Summer Season ◽  
Vertical Profiles ◽  
Experimental Database ◽  
Regional Features ◽  
Tropospheric Aerosol ◽  
The Mean ◽  
Mass Type ◽  
Radiative Characteristics

Abstract. An empirical model of vertical profiles of the aerosol optical characteristics is described. It has been constructed based on the data of multiyear airborne sensing of optical and microphysical characteristics of the tropospheric aerosol over West Siberia at the altitudes 0–5 km. The model proposed allows using season, air mass type, and time of the day as its input parameters. For solar radiative flux calculations, this empirical model has been tested for the mean conditions of the summer season. The available experimental database and the model developed on its basis are shown to be sufficient to perform these calculations taking into account the regional features of West Siberia.

The Stability of Ground Motions Randomly Synthesized for an Engineering Site

2013 ◽  
Vol 477-478 ◽  
pp. 1069-1074
Author(s):  
Hai Ming Liu ◽  
Xiaxin Tao ◽  
Li Yuan Wang
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Ground Motions ◽  
Source Models ◽  
The Mean ◽  
The Stability

The ground motions at two rock stations where motions were recorded during the great Wenchuan earthquae are randomly synthsized for 10 times. The mean response spectrum and mean PGA of each synthesis and the general mean spectrum and PGA after each synthesis are calculated. The result shows the fact that the general mean spectrum after 10 syntheses, and the general mean PGA could be improved just a little. It means that it is not necessary to synthsize ground motion many times for an engineering site in practice, if the mean spectrum and PG are taken from the syntheses by 30 source models.

Firn Densification: An Empirical Model

1980 ◽  
Vol 25 (93) ◽  
pp. 373-385 ◽  
Author(s):  
Michael M. Herron ◽  
Chester C. Langway
Keyword(s):  
Empirical Model ◽  
Accumulation Rate ◽  
Rate Equations ◽  
Constant Density ◽  
Square Root ◽  
Accumulation Rates ◽  
Densification Rate ◽  
Second Stage ◽  
The Mean ◽  
Two Stages

AbstractAn empirical model of firn densification from the surface to the zone of pore close-off has been constructed. Fundamental rate equations have been derived for the first two stages of densification. In the first stage, for densities less than 0.55 Mg m−3, the densification rate is proportional to the mean annual accumulation times the term (ρi−ρ), whereρis the density of the snow andρiis the density of pure ice. The densification rate in the second stage, where 0.55 Mg m−3&lt; ρ &lt; 0.8 Mg m−3, is proportional to the square root of the accumulation rate and to (ρi−ρ). Depth–density and depth–age calculations from this model are compared with observation. Model accumulation rates are within about 20% of values obtained by other techniques. It is suggested that depth intervals of constant density in some Antarctic cores may represent a synchronous event in the 1880 ’s when ten times the normal accumulation fell within a year or two.

Ground Motion Selection for Liquefaction Evaluation Analysis of Earthen Levees

2012 ◽  
Vol 28 (4) ◽  
pp. 1331-1351 ◽  
Author(s):  
Adda Athanasopoulos-Zekkos ◽  
Mustafa Saadi
Keyword(s):  
Ground Motion ◽  
Cross Sections ◽  
Ground Motions ◽  
Cyclic Stress ◽  
Cyclic Stress Ratio ◽  
Ground Motion Selection ◽  
Liquefaction Susceptibility ◽  
Wide Range ◽  
Dynamic Analyses ◽  
The Mean

Guidelines for selecting ground motions for liquefaction evaluation analysis of earthen levees are proposed. These guidelines were developed based on results from dynamic analyses of characteristic earthen levee cross sections using a wide range of ground motions (~1,500). The effect of a number of ground motion parameters on the dynamic response of the levees in terms of liquefaction susceptibility was studied, and the parameters that correlated best to the response were identified. For the liquefaction triggering evaluation, the mean period of the ground motion ( Tm) is best correlated to the cyclic stress ratio (CSR). Regression relationships between CSR and Tm are proposed for a series of levee types and shaking intensities.

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