scholarly journals Experience of diagnostics of engineering structures by the method of small impacts

2019 ◽  
Vol 6 (3) ◽  
Author(s):  
Andrey Yashnov ◽  
Igor Snejkov
Keyword(s):  
Natural Oscillation ◽  
Technical Condition ◽  
Dynamic Parameters ◽  
Engineering Structures ◽  
Vibration Diagnostics ◽  
Pedestrian Bridges ◽  
Bridge Structures ◽  
Low Sensitivity ◽  
Natural Oscillation Frequency

The problems of diagnostics of engineering structures during their service life are considered. As one of the promising methods, the method of vibration diagnostics for changing dynamic parameters (natural frequencies and decrements of oscillations, amplitudes and forms of oscillations) was chosen. The results of various studies in the field of vibration diagnostics of bridge structures are analyzed. The results of the study of the influence of various damages on the dynamic parameters of structures using finite element models are presented. Summarized data of long-term studies of the Siberian transport University to evaluate the technical state of structures based on measurement of natural oscillation frequency. The limitation of the method of vibration diagnostics for lower forms of vibration is associated with low sensitivity and significant influence of various factors on the results. However, in some cases, vibration diagnostics of structures under excitation of oscillations by small pulse effects can be effective. Examples of vibrodiagnostics of the state of structures are given. Vibrodiagnostics is particularly relevant in the study of the actual dynamic work of pedestrian bridges. Regular fixation of «digital dynamic portraits» allows you to track changes in technical condition. It is advisable to use methods of vibration diagnostics and in assessing the effectiveness of strengthening structures. In conclusion, it is noted that using the methods considered, it is possible to organize a system of periodic or continuous automated monitoring of the technical condition of bridges. This is especially important to prevent sudden failures of technically complex and unique structures, as well as in the case of serious damage to the load-bearing structures.

scholarly journals Wheeled Robot Dedicated to the Evaluation of the Technical Condition of Large-Dimension Engineering Structures

Robotics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 28
Author(s):  
Jarosław Domin ◽  
Marcin Górski ◽  
Ryszard Białecki ◽  
Jakub Zając ◽  
Krzysztof Grzyb ◽  
...  
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Technical Condition ◽  
Fiber Reinforced Polymer ◽  
Loading Capacity ◽  
Engineering Structures ◽  
Reinforced Polymer ◽  
Wheeled Robot

There are many reasons why engineering structures are at risk of losing their loading capacity during their long-term exploitation, which may lead to hazardous states. In such cases, structures must be strengthened. The most popular technique of strengthening is based on the use of composite materials—fiber-reinforced polymer (FRP) elements attached to the structure with the special resins. FRP elements are applied externally, often in hard to reach places, which makes it difficult to diagnose the durability and quality of such a connection. In this study, a combination of a modern thermographic method was proposed, which makes it possible to assess the degree of damage to the contact of the structure with the composite material along with the running platform (wheeled robot) equipped with a set of diagnostic sensors. The development potential of such a solution for subsequent projects was also indicated.

scholarly journals Geodetic monitoring of deformations of engineering structures

2021 ◽  
Vol 317 (2) ◽  
pp. 69-77
Author(s):  
G.M. Urazbaev ◽  
◽  
A.A. Altayeva ◽  
Zh.T. Kozhayev ◽  
M.G. Mustafin ◽  
...  
Keyword(s):  
Large Scale ◽  
Technical Condition ◽  
Engineering Structures ◽  
Term Operation ◽  
Special Services ◽  
Building Monitoring ◽  
Geodetic Control ◽  
The Republic ◽  
Instrumental Control

Unfortunately, all kinds of anthropogenic and natural factors contribute to the deformation of man-made structures. Geodetic control of buildings and structures, timely detection and elimination of deformations is a guarantee of long-term operation of the building. Monitoring is one of the most important tools to ensure the reliability and safety of multi-storey and large-scale buildings and structures during construction and operation. A significant amount of instrumental control during construction and operation is carried out by geodetic methods. Geodetic methods are used to determine both local and general deformations of buildings and structures, deviations of load-bearing, fencing structures from vertical and design drawings, foundations and soil settlements, through which the technical condition of the building or structure is specially assessed. Today, the analysis of deformations is an important task for every region of our country, especially for areas with changes in the earth's surface. The field of deformation research in the Republic of Kazakhstan is quite developed and there are many necessary materials to identify such changes. In our country, special services are organized to control any benchmarks and analyze the results of high-precision measurements in several cycles to detect any changes on the earth's surface. Therefore, this article provides an overview of both the classical methods of geodetic control and the tools and technologies used to determine the quantitative characteristics of the deformation of engineering objects.

Efficiency of application of the phase-chronometric method and neurodiagnostics for monitoring the degradation of rolling bearings during operation

2020 ◽  
pp. 43-50
Author(s):  
A.S. Komshin ◽  
K.G. Potapov ◽  
V.I. Pronyakin ◽  
A.B. Syritskii
Keyword(s):  
Life Cycle ◽  
Wavelet Analysis ◽  
Metrological Support ◽  
Rolling Bearing ◽  
Technical Condition ◽  
Measurement Information ◽  
Rolling Bearings ◽  
Vibration Diagnostics ◽  
Bearing Life ◽  
Alternative Approach

The paper presents an alternative approach to metrological support and assessment of the technical condition of rolling bearings in operation. The analysis of existing approaches, including methods of vibration diagnostics, envelope analysis, wavelet analysis, etc. Considers the possibility of applying a phase-chronometric method for support on the basis of neurodiagnostics bearing life cycle on the basis of the unified format of measurement information. The possibility of diagnosing a rolling bearing when analyzing measurement information from the shaft and separator was evaluated.

scholarly journals Coulomb stress analysis for several filling and operational scenarios at the Grand Ethiopian Renaissance Dam impoundment

2021 ◽  
Vol 80 (7) ◽  
Author(s):  
Austin Madson ◽  
Yongwei Sheng
Keyword(s):  
Coulomb Stress ◽  
Engineering Structures ◽  
Main Driver ◽  
Potential Reservoir ◽  
Coulomb Stress Analysis ◽  
Storage Change ◽  
Total Maximum ◽  
Western Ethiopia ◽  
Maximum Stresses

AbstractIncreased demand for power generation coupled with changing seasonal water uncertainty has caused a worldwide increase in the construction of large hydrologic engineering structures. That said, the soon-to-be-completed Grand Ethiopian Renaissance Dam (GERD) will impound the Blue Nile River in Western Ethiopia and its reservoir will encompass ~ 1763 km2 and store ~ 67 Gt (km3) of surface water. The impoundment will undergo maximum seasonal load changes of ~ 28 to ~ 36 Gt during projected seasonal hydroelectric operations. The GERD impoundment will cause significant subsurficial stresses, and could possibly trigger seismicity in the region. This study examines Coulomb stress and hydrologic load centroid movements for several GERD impoundment and operational scenarios. The maximum subsurficial Coulomb stress applied on optimally oriented fault planes from the full impoundment is ~ 186 kPa and over 30% of our model domain incurs Coulomb stresses ≥ 10 kPa, regardless of the impoundment period length. The main driver behind Coulomb stress and load centroid motion during impoundment is the annual, accumulated daily reservoir storage change. The maximum Coulomb stresses from the highest amplitude season of five long-term operational scenarios are around 36, 33, 29, 41, and 24% of the total maximum stresses from the entire GERD impoundment. Variations in annual Coulomb stresses during modeled GERD operations are attributed to the seasonal load per unit area, and partially to the initial seasonal water level. The spatial patterns and amplitudes of these stress tensors are closely linked to both the size and timing of GERD inflow/outflow rates, and an improved understanding of the magnitude and extent of these stresses provides useful information to water managers to better understand potential reservoir triggered seismic events from several different operational and impoundment strategies.

scholarly journals C-Reactive Protein and All-Cause Mortality in a Large Hospital-Based Cohort

2008 ◽  
Vol 54 (2) ◽  
pp. 343-349 ◽  
Author(s):  
Claudia Marsik ◽  
Lili Kazemi-Shirazi ◽  
Thomas Schickbauer ◽  
Stefan Winkler ◽  
Christian Joukhadar ◽  
...  
Keyword(s):  
Hospital Admission ◽  
Acute Phase ◽  
Cox Regression ◽  
Disease Risk ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Increased Risk ◽  
All Cause Mortality ◽  
Low Sensitivity

Abstract Background: C-reactive protein (CRP), an acute-phase protein, is a sensitive systemic marker of inflammation and acute-phase reactions. Testing CRP concentrations at hospital admission may provide information about disease risk and overall survival. Methods: All first-ever transmittals to the department of medical and chemical laboratory diagnostics for determination of low-sensitivity CRP (n = 274 515, 44.5% male, median age 51 years) between January 1991 and July 2003 were included [median follow-up time: 4.4 years (interquartile range, 2.3–7.4 years)]. The primary endpoint was all-cause mortality. Multivariate Cox regression adjusted for sex and age was applied for analysis. Results: Compared to individuals within the reference category (CRP <5 mg/L), hazard ratios (HR) for all-cause mortality increased from 1.4 (5–10 mg/L category) to 3.3 in the highest category (>80 mg/L, all P <0.001). CRP was associated with various causes of death. The relation of CRP to cancer death was stronger than to vascular death. Younger patients with increased CRP had relatively far worse outcome than older patients (maximal HR: ≤30 years: 6.7 vs >60 years: 1.7–3.7). Interestingly, both short- and long-term mortality were associated with increasing CRP concentrations (>80 mg/L: HR 22.8 vs 1.4). Conclusion: Measurement of low-sensitivity CRP at hospital admission allowed for the identification of patients at increased risk of unfavorable outcome. Our findings indicate that close attention should be paid to hospitalized patients with high CRP not only because of very substantial short-term risk, but also long-term excess risk, the basis for which needs to be determined.

Protection of railway infrastructure objects against electrical corrosion

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Liudmyla Trykoz ◽  
Svetlana Kamchatnaya ◽  
Dmytro Borodin ◽  
Armen Atynian ◽  
Roman Tkachenko
Keyword(s):  
Leakage Current ◽  
Electrical Resistance ◽  
Electrical Current ◽  
Leakage Currents ◽  
Destructive Effect ◽  
Accelerated Corrosion ◽  
Content Type ◽  
Pedestrian Bridges ◽  
Railway Infrastructure ◽  
Bridge Structures

Purpose The purpose of this paper is to develop a technological method of protection against electrical corrosion. One more way to protect the objects is to prevent the electrical current from getting to them. For example, railway objects are surrounded with a material with raised electrical resistance. Design/methodology/approach The railway infrastructure objects (foundations, contact-line supports, reinforced concrete sub-bases, bridge structures, pipelines of engineering networks, supports of passenger platforms and pedestrian bridges, concrete plinth walls of station buildings) are subjected to destruction due to the action of electrical current. One of destruction factors is a corrosion of the concrete constructions which is caused by the leakage current action. Findings Leakage currents and stray currents bypass the structure of supports of high passenger platforms or pipes of engineering networks. These currents spread by the line with the least resistance outside of the structures. Research limitations/implications Electrical leakage current from the rails gets into such structures through sleepers, ballast and soil and leads to accelerated corrosion leaching of concrete. Practical implications The constructions are protected against the destructive effect of electrical corrosion on the metal or concrete of the structure. This scheme is suitable for the construction and reconstruction of railway structures which operate on electrified sections of railways. Originality/value Schemes of technological solution are proposed for protection of foundations, supports of high passenger platforms, pipelines of engineering networks, etc. For this, the arrangement of soil-contained screens with big electrical resistance is suggested.

scholarly journals Analysis of the natural oscillation frequency of the long-span trusses with flanged connections

2021 ◽  
pp. 76-85
Author(s):  
Татьяна Георгиевна Рытова ◽  
Людмила Анатольевна Максимова ◽  
Анастасия Георгиевна Николаева ◽  
Татьяна Михайловна Макарова ◽  
Надежда Георгиевна Пфаненштиль
Keyword(s):  
Dynamic Characteristics ◽  
Vibration Frequency ◽  
Natural Vibration ◽  
Natural Oscillation ◽  
Natural Vibration Frequency ◽  
Building Structures ◽  
Long Span ◽  
Local Areas ◽  
Calculation Results ◽  
Natural Oscillation Frequency

Приводится анализ частоты собственных колебаний большепролетной фермы с фланцевыми соединениями. Выполнен расчет фланцевого соединения с различными случаями исключения болтов из работы соединения. Анализ результата расчета показал, что возникновение повреждений и дефектов конструкций здания в локальных зонах, величина которых несущественно снижает общую жесткость каркаса, практически не влияет на динамические характеристики каркаса. The analysis of the natural vibration frequency of a large-span truss with flanged connections is given. The calculation of the flange connection with various cases of exclusion of bolts from the connection operation is performed. Analysis of the calculation results showed that the occurrence of damage and defects in the building structures in local areas, the value of which significantly reduces the overall rigidity of the frame, practically does not affect the dynamic characteristics of the frame.

scholarly journals Experimental study of a lock-in phenomenon in the case of a mechanical oscillator flowmeter

Mechanik ◽  
2020 ◽  
Vol 93 (7) ◽  
pp. 13-15
Author(s):  
Maciej Szudarek ◽  
Mateusz Turkowski
Keyword(s):  
Experimental Study ◽  
Pulsatile Flow ◽  
Oscillation Frequency ◽  
Measurement Errors ◽  
Natural Oscillation ◽  
Mechanical Oscillator ◽  
Pulsation Amplitude ◽  
Lock In ◽  
Natural Oscillation Frequency

Oscillatory flowmeters are susceptible to pulsatile flow and mechanical oscillator flowmeters are no exception. The experimental study was conducted to determine possible measurement errors for specific pulsation amplitude thresholds. The study verified that no frequency lock-in takes place for pulsation frequencies which are subharmonics of the natural oscillation frequency, nor for harmonics higher than the 2nd.

Dynamic Parameters of Prestressed Hanging Systems

2021 ◽  
Vol 887 ◽  
pp. 698-705
Author(s):  
N.S. Razzokov ◽  
U.S. Akhmadiyorov
Keyword(s):  
Operating Conditions ◽  
Local Damage ◽  
Dynamic Parameters ◽  
Dynamic Effects ◽  
Static Loads ◽  
Long Span ◽  
Design Basis ◽  
Operational Safety ◽  
Properties Of Materials

The dynamic parameters of long-span prestressed one and two-belt hanging roofs, for which the seismic wavelengths are commensurate with the dimensions of the structure in plan, are considered. Calculated expressions have been obtained to determine the dynamic parameters for symmetric and skew-symmetric oscillations depending on the length of seismic waves.To ensure the operational safety of unique buildings and structures, we studied the change in the structural properties of materials from unfavorable operating conditions, long-term, beyond design-basis static loads, high-intensity dynamic effects, compliance of the support contours and the possibility of local damage and from the failure of cables of the structures under study.

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