scholarly journals Features of the joint work of structures and pile foundations on loess foundations

2021 ◽  
Vol 264 ◽  
pp. 02048
Author(s):  
Zakiryo Buzrukov ◽  
Ilkhom Yakubjanov ◽  
Mukhtorzhon Umataliev
Keyword(s):  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Frequency Characteristics ◽  
Pile Foundations ◽  
Frame Structures ◽  
Bending Moments ◽  
Joint Work ◽  
Shear Forces ◽  
Industrial Construction ◽  
Different Levels

This paper presents the results of using frame structures in industrial construction with pile foundations under dynamic influences. In the course of the study, a set of formulas were derived to determine the amplitude-frequency characteristics of the system "flat frame-grillage-group of piles" at different levels of action of loads excited from the seismic platform, and natural frequencies were calculated, bending moments, shear forces at the points of fixation of the system elements were determined. The results of calculations and analysis make it possible to obtain the dynamic characteristics of a flat frame on pile foundations, which are necessary for subsequent calculations.

Numerical Analysis of Forced Vibrations of Beams

1953 ◽  
Vol 20 (1) ◽  
pp. 53-56
Author(s):  
N. O. Myklestad
Keyword(s):  
Natural Frequencies ◽  
Driving Forces ◽  
Bending Moments ◽  
Internal Damping ◽  
Shear Forces ◽  
Natural Modes ◽  
Tabular Method ◽  
Modes Of Vibration ◽  
The One ◽  
Phase Angles

Abstract In this paper a simple tabular method is developed by which the vibration amplitudes, bending moments, and shear forces of a beam of variable but symmetrical cross section, carrying any number of concentrated masses and acted on by any number of harmonically varying forces, can be found. The driving forces must all have the same frequency but the phase angles may be different. The method is an extension of the one employed by the author to find natural modes of vibration of beams, but in the case of forced vibration only one application of the tabular calculations is necessary, making it essentially a far simpler problem than that of finding the natural modes. Internal damping of the beam material is easily considered and should always be taken into account if there is any danger that the forced frequency is near any one of the natural frequencies.

scholarly journals INTERACTION OF FRAME STRUCTURES WITH ROLLING STOCK

2021 ◽  
Vol 445 (1) ◽  
pp. 22-28
Author(s):  
S. S. Abdullayev ◽  
I. S. Bondar ◽  
G. B. Bakyt ◽  
G. K. Ashirbayev ◽  
A. M. Budiukin ◽  
...  
Keyword(s):  
Natural Frequencies ◽  
Spectral Curve ◽  
Technical Condition ◽  
Rolling Stock ◽  
Frame Structures ◽  
Joint Work ◽  
Main Bearing ◽  
Natural Oscillations ◽  
Railway Bridges ◽  
Damage Rate

Need of use of mobile measuring computer systems when performing diagnostics of bridges is shown and also the analysis of amplitude-phase-frequency characteristics frame reinforced concrete and metal flying structures of railway bridges is provided at the movement of the train. This in turn allows to estimate conditions of span structures by width of ranges in points of half energy of spectral curve in the area of resonances. Assessment of technical condition and diagnostics of supported artificial structures is carried out according to dynamic parameters. According to this method frequency of natural oscillations is determined from peak values of averaged spectral densities of reduced power. Comparing width of the received ranges to ranges of the new (intact) flying structures it is possible to estimate degree of wear and a damage rate of elements of designs. Based on the results of the calculations, it has been confirmed that the inclusion of elements of the bridge web and the upper structure of the track in the joint work with the main bearing structures increases the accuracy of solving the problem of determining natural frequencies.

scholarly journals Dynamic characteristics of pilot boards of structures

2021 ◽  
Vol 264 ◽  
pp. 02053
Author(s):  
Khorisboy Alimov ◽  
Zakiryo Buzrukov ◽  
Mirzohid Turgunpulatov
Keyword(s):  
Dynamic Characteristics ◽  
Field Tests ◽  
Frequency Characteristics ◽  
Structure Group ◽  
Pile Foundations ◽  
Soil Conditions ◽  
Special Technique ◽  
Theoretical Studies ◽  
System A ◽  
Earthquake Resistant

This work is devoted to studying the issues of vibrations of pile foundations, taking into account soil conditions for various types of fastening of piles to structures and the development of rational methods for choosing the parameters of piles and their number in earthquake-resistant construction. Based on the results of theoretical studies, resonance curves were constructed for three types of fastening of the "structure-group of piles" system. A special technique was proposed, and a series of field tests were carried out to determine the amplitude-frequency characteristics of the system.

scholarly journals Determining the dynamic characteristics of elastic shell structures

2021 ◽  
Vol 6 (7 (114)) ◽  
Author(s):  
Irina Polyakova ◽  
Raikhan Imambayeva ◽  
Bakyt Aubakirova
Keyword(s):  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Elastic Shell ◽  
Physical And Mechanical Properties ◽  
Frequency Characteristics ◽  
Dynamic Loads ◽  
Measuring Instruments ◽  
Building Structures ◽  
Elastic Elements

Building structures are very often operated under the action of dynamic loads, both natural and man-made. The calculation of structures under the influence of static loads has been quite widely studied in detail. When structures are exposed to dynamic loads, additional tests are carried out, where measuring instruments are installed on the structures to register stresses and deformations that occur during dynamic influences. Elastic elements are the responsible functional unit of many measuring instruments. Therefore, the quality of elastic elements ensures the operational stability of the entire structure. This determines the increased attention that is paid to technology and construction to elastic elements. Previously, the work of elastic elements made of homogeneous mono materials with the same physical and geometric properties in all directions and over the entire surface of the element was studied. The elastic element was considered as a shell of rotation with a complex shape of the meridian and various physical and mechanical properties at various points caused by uneven reinforcement. Two types of reinforcement were implied ‒ radial and circular. Elastic shell elements (ESE) operate under conditions of dynamic loading. The equation was derived for determining the dynamic characteristics of inhomogeneous elastic elements. The dependences of the first three natural frequencies of oscillations on the thickness of the shell and the depth of the corrugation and the first two natural frequencies of oscillations on the thickness of the shell have been analyzed. The amplitude-frequency characteristics (AFC) and the phase-frequency characteristics (PFC) of the shell depending on the geometric parameters have been calculated. All these results could significantly improve the quality of the readings of the instruments, which depend on the sensitivity of the shell elastic elements. And it, in turn, depends on the geometric and physical properties of the shell elastic elements.

Large Deflection of a Rectangular Plate Resting on a Pasternak-Type Elastic Foundation

1977 ◽  
Vol 44 (3) ◽  
pp. 509-511 ◽  
Author(s):  
P. K. Ghosh
Keyword(s):  
Rectangular Plate ◽  
Elastic Foundation ◽  
Large Deflection ◽  
Lateral Load ◽  
Bending Moments ◽  
Shear Forces ◽  
Simply Supported ◽  
Base Parameters ◽  
Square Plate

The problem of large deflection of a rectangular plate resting on a Pasternak-type foundation and subjected to a uniform lateral load has been investigated by utilizing the linearized equation of plates due to H. M. Berger. The solutions derived and based on the effect of the two base parameters have been carried to practical conclusions by presenting graphs for bending moments and shear forces for a square plate with all edges simply supported.

scholarly journals Modal Perturbation Method for the Dynamic Characteristics of Timoshenko Beams

2005 ◽  
Vol 12 (6) ◽  
pp. 425-434 ◽  
Author(s):  
Menglin Lou ◽  
Qiuhua Duan ◽  
Genda Chen
Keyword(s):  
Perturbation Method ◽  
Dynamic Characteristics ◽  
Timoshenko Beam ◽  
Natural Frequencies ◽  
Solution Process ◽  
Equation Of Motion ◽  
Timoshenko Beams ◽  
Algebraic Equations ◽  
Nonlinear Algebraic Equations ◽  
Shear Distortion

Timoshenko beams have been widely used in structural and mechanical systems. Under dynamic loading, the analytical solution of a Timoshenko beam is often difficult to obtain due to the complexity involved in the equation of motion. In this paper, a modal perturbation method is introduced to approximately determine the dynamic characteristics of a Timoshenko beam. In this approach, the differential equation of motion describing the dynamic behavior of the Timoshenko beam can be transformed into a set of nonlinear algebraic equations. Therefore, the solution process can be simplified significantly for the Timoshenko beam with arbitrary boundaries. Several examples are given to illustrate the application of the proposed method. Numerical results have shown that the modal perturbation method is effective in determining the modal characteristics of Timoshenko beams with high accuracy. The effects of shear distortion and moment of inertia on the natural frequencies of Timoshenko beams are discussed in detail.

Dynamic characteristics of horizontally curved bridges

2017 ◽  
Vol 24 (19) ◽  
pp. 4465-4483 ◽  
Author(s):  
Mohsen Amjadian ◽  
Anil K Agrawal
Keyword(s):  
Free Vibration ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Response Spectrum ◽  
Translational Motion ◽  
Free Vibration Analysis ◽  
Mode Shapes ◽  
Curved Bridges ◽  
Horizontally Curved ◽  
Horizontally Curved Bridges

Horizontally curved bridges have complicated dynamic characteristics because of their irregular geometry and nonuniform mass and stiffness distributions. This paper aims to develop a simplified and practical method for the calculation of the natural frequencies and mode shapes of horizontally curved bridges that would be of interest to bridge engineers for the estimation of the seismic response of these types of bridges. For this purpose, a simple three-degree-of-freedom (3DOF) dynamic model for free vibration equation of this type of bridge has been developed. It is shown that the translational motion of the deck of horizontally curved bridges in the direction that is perpendicular to their axis of symmetry is always coupled with the rotational motion of the deck, regardless of the location of the stiffness center. The model is further exploited to develop closed-form formulas for the estimation of the maximum displacements of the corners of the deck of one-way asymmetric horizontally curved bridges. The accuracy of the model is verified by finite-element model of a horizontally curved bridge prototype in OpenSEES. Finally, the model is utilized to study the influence of the location of the stiffness center with respect to the deck curvature center on the natural frequency and the maximum displacements of the corners of the deck for different curvatures of the deck. The results of free vibration analysis show that the natural frequencies of one-way asymmetric horizontally curved bridges, in general, increase with the increase of the subtended angle of the deck. The results of earthquake response spectrum analysis show that the increase in the subtended angle of one-way asymmetric horizontally curved bridges decreases the radial displacements of the corners of the deck but increases the azimuthal displacement. These two responses both increase with the increase in the distance between the stiffness center and the curvature center.

Dynamic Characteristics Analysis for the Headstock of a Vertical Machining Center

2016 ◽  
Vol 836-837 ◽  
pp. 348-358
Author(s):  
Zhe Li ◽  
Song Zhang ◽  
Yan Chen ◽  
Peng Wang ◽  
Ai Rong Zhang
Keyword(s):  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Vibration Characteristics ◽  
Numerical Control ◽  
Vibration Test ◽  
Machining Accuracy ◽  
Modal Test ◽  
Machining Center ◽  
Characteristics Analysis ◽  
Nc Machine

Dynamic characteristics of numerical control (NC) machine tools, such as natural frequency and vibration property, directly affect machining efficiency and finished surface quality. In general, low-order natural frequencies of critical components have significant influences on machine tool’s performances. The headstock is the most important component of the machine tool. The reliability, cutting stability, and machining accuracy of a machining center largely depend on the structure and dynamic characteristics of the headstock. First, in order to obtain the natural frequencies and vibration characteristics of the headstock of a vertical machining center, modal test and vibration test in free running and cutting conditions were carried out by means of the dynamic signal collection and analysis system. According to the modal test, the first six natural frequencies of the headstock were obtained, which can not only guide the working speed, but also act as the reference of structural optimization aiming at frequency-shift. Secondly, by means of the vibration test, the vibration characteristics of the headstock were obtained and the main vibration sources were found out. Finally the corresponding vibration reduction plans were proposed in this paper. That provides the reference for improving the performance of the overall unit.

A Study on the Effect of Bird Hit Damage on the Dynamic Response of Aero-Engine Fan Blade

2013 ◽  
Author(s):  
Hithesh Channegowda ◽  
Raghu V. Prakash ◽  
Anandavel Kaliyaperumal
Keyword(s):  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Foreign Object Damage ◽  
Aero Engine ◽  
Need To Evaluate ◽  
Bird Impact ◽  
Post Impact ◽  
Fan Blade ◽  
Critical Components

Fan blades of an aero-engine assembly are the critical components that are subjected to Foreign Object Damage (FOD) such as bird impact. Bird impact resulting in deformation damage onto set of blades, which in turn alters the blade mass and stiffness distribution compared to undamaged blades. This paper presents the numerical evaluation of dynamic characteristics of bird impact damaged blades. The dynamic characteristics evaluated are the natural frequencies and mode shapes of post impact damaged set of blades and the results are compared with undamaged set of blades. The frequencies and mode shapes are evaluated for the damaged blades, with varying angles of bird impact and three blade rotational speeds. Study reveals that first bending and torsional frequencies of deformed blades are significantly affected compared to undamaged set of blades. Study emphasize the need to evaluate the natural frequencies deformed blades, that has direct bearing on High Cycle Fatigue (HCF) life of the blade, to ensure post damaged blades operate safely for certain time to reduce inflight accidents and safe landing.

Dynamic Characteristics of a Long-Span Cable-Stayed Bridge

2011 ◽  
Vol 480-481 ◽  
pp. 1496-1501
Author(s):  
Liu Hui
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Iteration Method ◽  
Natural Frequencies ◽  
Element Model ◽  
Vibration Modes ◽  
Cable Stayed Bridge ◽  
Long Span ◽  
Subspace Iteration ◽  
Floating System

In order to study the dynamic characteristics of a super-long-span cable-stayed bridge which is semi-floating system, the spatial finite element model of this cable-stayed bridge was established in ANSYS based on the finite element theory.Modal solution was conducted using subspace iteration method, and natural frequencies and vibration modes were obtained.The dynamic characteristics of this super-long-span cable-stayed bridge were then analyzed.Results showed that the super-long-span cable-stayed bridge of semi-floating system has long basic cycle, low natural frequencies, dense modes and intercoupling vibration modes.

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