scholarly journals Performance of Ground Anchored Walls Subjected to Dynamic and Pseudo-Static Loading

2021 ◽  
Vol 7 (6) ◽  
pp. 974-987
Author(s):  
Arash Saeidi Rashk Olia ◽  
Mohammad Oliaei ◽  
Heisam Heidarzadeh
Keyword(s):  
Dynamic Load ◽  
Static Loading ◽  
Peak Acceleration ◽  
Ground Acceleration ◽  
Ground Anchors ◽  
Axial Forces ◽  
Data Analyses ◽  
Load Peak ◽  
Static Coefficient ◽  
Good Agreement

This study investigates the response of pre-stressed anchored excavation walls under dynamic and pseudo-static loadings. A finite difference numerical model was developed using FLAC2D, and the results were successfully validated against full-scale experimental data. Analyses were performed on 10, and 20-m-height stabilized excavated slopes with 60° to 90° of inclination angle with the horizon to represent an applicable variety of wall geometries. In dynamic analysis, the statically stabilized models were subjected to 0.2 to 0.6g of the dynamic peak acceleration to evaluate the effect of ground acceleration on their performance. Furthermore, pseudo-static analyses were performed on the statically stabilized models with pseudo-static coefficients ranging from 0.06 to 0.22. The results revealed that ground anchored slopes generally showed acceptable performances under dynamic loading, while higher axial forces were induced to ground anchors in higher and steeper models. Furthermore, comparing the results of dynamic and pseudo-static analyses showed a good agreement between the two methods' predictions in the mobilized axial force along the ground anchors. Pseudo-static coefficients were then proposed to replicate dynamic results, considering the slope geometry and dynamic load peak acceleration. The results revealed that higher and steeper stabilized slopes required higher values of pseudo-static coefficients to match the dynamic predictions successfully. The results indicate that pseudo-static coefficient tend to increase with the increase in dynamic load peak acceleration in any given model. Doi: 10.28991/cej-2021-03091703 Full Text: PDF

Comparing Shock, Random and Sine Vibration Loads of the Electronic Equipment

2005 ◽  
Author(s):  
Frank Fan Wang
Keyword(s):  
Dynamic Load ◽  
Random Vibration ◽  
Sine Wave ◽  
Electronic Equipment ◽  
Dynamic Loads ◽  
Peak Acceleration ◽  
Maximum Acceleration ◽  
Dynamic Excitations ◽  
Dynamic Damage ◽  
Resonant Point

It is a challenge to correlate different dynamic loads. Often, attempts are made to compare the peak acceleration of sine wave to the root mean square (RMS) acceleration of random vibration and shock. However, peak sine acceleration is the maximum acceleration at one frequency. Random RMS is the square root of the area under a spectral density curve. These are not equivalent. This paper is to discuss a mathematical method to compare different kinds of dynamic damage at the resonant point of the related electronic equipment. The electronic equipment will vibrate at its resonance point when there are dynamic excitations. The alternative excitation at the resonant frequency causes the most damage. This paper uses this theory to develop a method to correlate different dynamic load conditions for electronic equipment. The theory is that if one kind of dynamic load causes the same levels of damaging effects as the other, the levels of vibration can then be related.

Numerical Modeling of Near Fault Seismic Ground Motion for Denali Fault

2021 ◽  
Vol 12 (2) ◽  
pp. 0-0
Keyword(s):  
Ground Motion ◽  
Peak Ground Acceleration ◽  
Numerical Study ◽  
Ground Motions ◽  
Numerical Results ◽  
Fault Rupture ◽  
Ground Acceleration ◽  
Denali Fault ◽  
Near Fault ◽  
Good Agreement

An effective earthquake (Mw 7.9) struck Alaska on 3 November, 2002. This earthquake ruptured 340 km along Susitna Glacier, Denali and Totschunda faults in central Alaska. The peak ground acceleration (PGA) was recorded about 0.32 g at station PS10, which was located 3 km from the fault rupture. The PGA would have recorded a high value, if more instruments had been installed in the region. A numerical study has been conducted to find out the possible ground motion record that could occur at maximum horizontal slip during the Denali earthquake. The current study overcomes the limitation of number of elements to model the Denali fault. These numerical results are compared with observed ground motions. It is observed that the ground motions obtained through numerical analysis are in good agreement with observed ground motions. From numerical results, it is observed that the possible expected PGA is 0.62 g at maximum horizontal slip of Denali fault.

Probabilistic Estimates of Maximum Seismic Horizontal Ground Acceleration on Rock in Alaska and the Adjacent Continental Shelf

1985 ◽  
Vol 1 (2) ◽  
pp. 285-306 ◽  
Author(s):  
Paul C. Thenhaus ◽  
Joseph I. Ziony ◽  
William H. Diment ◽  
Margaret G. Hopper ◽  
David M. Perkins ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Return Period ◽  
Chukchi Sea ◽  
Poisson Model ◽  
Seismic Source ◽  
Gulf Of Alaska ◽  
Historical Record ◽  
Peak Acceleration ◽  
Ground Acceleration ◽  
Predicted Values

Estimates of ground motion hazard from earthquakes in Alaska and the adjacent continental shelf indicate that, for all the exposure times considered, the predicted values of peak acceleration are highest in the Gulf of Alaska and near the major active strike-slip faults of southern Alaska. The evaluations assume a Poisson model of earthquake occurrence and are based on seismic source zones delineated from regional geologic considerations and the historical record of earthquakes. Calculated peak acceleration values for a return period of 100 years range as high as 0.4 g in the Gulf of Alaska sector between Kodiak and Kayak Islands, are about 0.2 g near Anchorage, and 0.1 g near Fairbanks. Values for most of the rest of the state are estimated to be less than .04 g; however, most of the southern Alaska industrial and population base lies within the 0.2 g contour. For a return period of 500 years, peak accelerations are estimated as high as 0.8 g for parts of southeastern Alaska near the Fairweather fault, 0.6 g or greater for part of the Gulf of Alaska, and are about 0.45 g and 0.2 g, respectively, for the Anchorage and Fairbanks areas. Values of acceleration for a return period of 2,500 years exceed 0.6 g for much of southern Alaska and are 0.8 g or greater near the Fairweather and central Denali faults; estimated values are 0.1 g or greater for nearly all of onshore Alaska and for the continental shelf areas of the Bering Sea, Norton and Kotzebue Sounds, southern Chukchi Sea and southeastern Beaufort Sea.

scholarly journals FEM effective suggestion of guitar construction

2006 ◽  
Vol 54 (2) ◽  
pp. 23-30
Author(s):  
Vladimír Dániel ◽  
Petr Koňas
Keyword(s):  
Harmonic Analysis ◽  
Static Loading ◽  
Natural Frequencies ◽  
Mechanical Function ◽  
Suggested Model ◽  
Low Frequencies ◽  
Final Model ◽  
High Frequencies ◽  
Equal Temperament ◽  
Good Agreement

Modal analysis of the whole guitar construction was performed. The results of eigenfrequencies were obtained. Stress in strings affects not only static loading of material, but also shift of eigenfrequencies. From obtained natural frequencies for solved spectrum such frequencies were used which coincides with assumed ribs new positions of ribs were suggested. Other ribs which do not carry out the mechanical function were removed. Also static reaction was evaluated and new position of ribs was adjusted. For final model new eigenfrequencies were computed and compared with previous ones. Significant changes were revealed in low frequencies (bellow 400 Hz) where fewer amounts of natural shapes were obtained. Approximately 50% were lost by adding of ribs. For chosen frequencies of equal temperament the harmonic analysis was performed. The analysis proved ability of oscillation for frequencies far of natural frequencies. The final model satisfies the requirement of minimization of static stress in material due to strings and allows very effective oscillation of top the guitar resonance board. In comparison with literature good agreement in amplitude size of front board and amount of modes in appropriate frequencies were achieved. Suggested model even offers higher amount of natural shapes in comparison with literature, namely in high frequencies. From additional comparison of eigenfrequencies and natural shapes the influence of ribs position on natural shapes was approved.

scholarly journals Serviceability of Reinforced Concrete Gable Roof Beams with Openings under Static Loads

2019 ◽  
Vol 9 (5) ◽  
pp. 4813-4817
Author(s):  
M. A. J. Hassan ◽  
A. F. Izzet
Keyword(s):  
Reinforced Concrete ◽  
Static Loading ◽  
Analytical Study ◽  
Magnification Factor ◽  
Concentrated Force ◽  
Static Loads ◽  
Gable Roof ◽  
Direct Stiffness ◽  
Crack Widths ◽  
Good Agreement

This paper presents an analytical study on the serviceability of reinforced concrete gable roof beams with openings of different sizes, based on an experimental study which includes 13 concrete gable roof beams with openings under static loading. For deflection and crack widths under static loading at service stage, a developed unified calculation procedure has been submitted, which includes prismatic beams with one opening subjected to flexure concentrated force. The deflection has been calculated with two methods: the first method calculated deflections via relevant equations and the second was Direct Stiffness Method in which the beam is treated as a structural member with several segments constituting the portions with solid sections and those with sections crossed by the opening. The crack width was calculated with the ACI code’s equation with a proposed magnification factor equal to 1.125. The analytical results were compared with the experimental ones and a good agreement was obtained.

scholarly journals Comparative characteristics of changes in central hemodynamics during early recovery after different exercise regimes

2021 ◽  
Vol 27 (2) ◽  
pp. 47-52
Author(s):  
H.V. Lukyantseva ◽  
O.M. Bakunovsky ◽  
S.S. Malyuga ◽  
T.M. Oliinyk ◽  
N.R. Manchenko ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cardiovascular System ◽  
Dynamic Loading ◽  
Vascular Resistance ◽  
Dynamic Load ◽  
Static Loading ◽  
Circulatory System ◽  
The Body ◽  
Central Hemodynamics ◽  
Early Recovery

The cardiovascular system is one of the most important functional systems of the body, which determine the level of physical performance of the body. Insufficient study of the response of the circulatory system to the combination of strength training with endurance exercises requires more detailed comparative studies of the impact of dynamic and static loads on the indicators of central hemodynamics. Accordingly, the aim of our study was to study the characteristics of the reaction of the cardiovascular system in the period of early recovery after dosed exercise of a dynamic and static nature. The study examined the response of the central hemodynamics of young men in the period of early recovery after dynamic loading (Martine functional test) and static loading (holding on the stand dynamometer DS-200 force with a power of 50% of maximum standing force). The change in circulatory system parameters was recorded using a tetrapolar thoracic impedance rheoplethysmogram on a computerized diagnostic complex “Cardio +”. It is established that the dynamic load in the period of early recovery does not cause a significant positive chronotropic effect, leads to a decrease in vascular resistance of blood flow, to an increase in pulse blood pressure. The increase in cardiac output is mainly due to the increase in stroke volume, which indicates a fairly high functional reserves of the heart. It is revealed that under conditions of static loading the reaction of central hemodynamics and the course of early recovery are radically different from the changes of indicators under dynamic loading. In persons with a normodynamic type of reaction to dynamic load, there are no significant changes in the minute volume of blood at a similar volume of active muscle mass static load. Meeting the metabolic needs of working skeletal muscles and compensating for the oxygen debt is realized by increasing the total peripheral vascular resistance and increasing systolic blood pressure in the postpartum period. The physiological meaning of this phenomenon is to maintain a sufficient level of venous return of blood to ensure the pumping function of the heart.

Non-Linear Analysis of Cable Stayed Bridges

2018 ◽  
Vol 6 (9) ◽  
pp. 36
Author(s):  
Zuber Ahmed ◽  
Esar Ahmed
Keyword(s):  
Response Spectrum ◽  
Research Work ◽  
Structural Response ◽  
Time History ◽  
Mode Shapes ◽  
Span Length ◽  
Ground Acceleration ◽  
Axial Forces ◽  
Aesthetic Appearance ◽  
Cable Stayed Bridges

The concept of cable-stayed bridges dates back to the seventeenth century. Due to their aesthetic appearance, efficient utilization of material, and availability of new construction technologies, cable-stayed bridges have gained much popularity in the last few decades. After successful construction of the Sutong Bridge, a number of bridges of this type have been proposed and are under construction, which calls for extensive research work in this field. Nowadays, very long span cable-stayed bridges are being built and the ambition is to further increase the span length using shallower and slender girders. In order to achieve this, accurate procedures need to be developed which can lead to a thorough understanding and a realistic prediction of the bridge’s structural response under different load conditions.In the present study, an attempt has been made to analyze the seismic response of cable stayed bridges with single pylon and two equal side spans. This study has made an effort to analyze the effect of both static and dynamic loadings on cable-stayed bridges and corresponding response of the bridge with variations in span length, pylon height and pylon shape. Comparison of static analysis results have been made for different configuration of bridges - their mode shapes, time period, frequency, pylon top deflection, maximum deck deflection; and longitudinal reaction, lateral reaction and longitudinal moment at pylon bottom. Time history analysis results have been investigated for different configuration of bridges under the effects of three earthquakes response spectrum (Bhuj, El Centro and Uttarkashi) - axial forces in stay cables, deck deflections and stress diagrams at maximum peak ground acceleration of the above mentioned earthquakes.

The Whittier Narrows, California Earthquake of October 1, 1987—Simulation of Recorded Accelerations

1988 ◽  
Vol 4 (1) ◽  
pp. 139-156 ◽  
Author(s):  
D. Wald ◽  
P. G. Somerville ◽  
L. J. Burdick
Keyword(s):  
Los Angeles ◽  
Radiation Effects ◽  
Site Response ◽  
Kinematic Model ◽  
Response Spectra ◽  
Rupture Process ◽  
Peak Acceleration ◽  
Source Information ◽  
Ground Acceleration ◽  
Time Histories

We have simulated accelerograms from many of the strong motion stations close to the mainshock of the 1987 Whittier Narrows earthquake using a semi-empirical Green's function summation technique. This method allows gross aspects of the source rupture process to be treated deterministically using a kinematic model based on first motion studies, teleseismic modeling and the distribution of aftershocks. Stochastic aspects of the rupture process are then included to simulate irregularity in both rupture and slip velocity. Gross aspects of wave propagation are modeled using theoretical Green's functions calculated with generalized rays. Detailed aspects of the source radiation at high frequencies, as well as unmodeled propagational aspects such as scattering, are included empirically by using multiple recordings of a smaller Imperial Valley earthquake as empirical source functions. Our main objective is to see how well we can predict the peak ground accelerations, time histories and response spectra of ground motions of a moderate sized earthquake within the Los Angeles Basin having limited detailed source information. We find that the simulations predict the observations accurately enough to identify which phases and amplitudes in the observed data may be due to local site response rather than source or radiation effects. Comparisons between observed and simulated accelerograms for all the stations modeled are made using peak ground acceleration, and using time histories and response spectra for the stations that have been hand-digitized to date. The Bright Avenue Whittier station has the largest simulated peak acceleration, in agreement with the recorded peak acceleration data.

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