This study focuses on utilizing computer modeling and simulation techniques, specifically the ANSYS software, to analyze the dynamics of bridge structures. The primary objective was to study the ...vibrations of a riverbed metal bridge structure and determine their characteristics. The research involved theoretical dynamic calculations considering the design features of the bridge components and the materials used in their construction. The obtained results enabled the determination of resonance frequencies for the vibration modes. By utilizing the ANSYS software, a three-dimensional virtual model of the bridge structure was created, allowing for a detailed analysis of its dynamic behavior. The first three vibration modes of the riverbed metal bridge structure were calculated, and numerical results were obtained for six modes. The findings of this research have practical significance as they provide informed decision-making support during the construction, maintenance, and modernization of bridge structures. The study of bridge dynamics using advanced technologies contributes to enhancing the safety, reliability, and longevity of these vital infrastructure assets.
Niniejsze badanie koncentruje się na wykorzystaniu technik modelowania komputerowego i symulacji, w szczególności oprogramowania ANSYS, do analizy dynamiki konstrukcji mostowych. Głównym celem było zbadanie drgań metalowej konstrukcji mostu w korycie rzeki i określenie ich charakterystyki. Badania obejmowały teoretyczne obliczenia dynamiczne uwzględniające cechy konstrukcyjne elementów mostu oraz materiały użyte do ich budowy. Uzyskane wyniki umożliwiły wyznaczenie częstotliwości rezonansowych dla postaci drgań. Wykorzystując oprogramowanie ANSYS stworzono trójwymiarowy wirtualny model konstrukcji mostu, pozwalający na szczegółową analizę jego dynamicznego zachowania. Obliczono trzy pierwsze postacie drgań metalowej konstrukcji mostu koryta rzeki i uzyskano wyniki numeryczne dla sześciu postaci. Wyniki tych badań mają znaczenie praktyczne, ponieważ zapewniają świadome wsparcie w podejmowaniu decyzji podczas budowy, utrzymania i modernizacji obiektów mostowych. Badanie dynamiki mostów przy użyciu zaawansowanych technologii przyczynia się do poprawy bezpieczeństwa, niezawodności i trwałości tych kluczowych elementów infrastruktury.
In the study, based on the model of acoustic emission during the destruction of a composite material by shear force according to the Von Mises criterion, the effect of non-uniformity of the ...destruction process on the generated acoustic emission signal is simulated. The study under the accepted modeling conditions allows us to determine the patterns of changes in the amplitude envelope of acoustic emission signals at various stages of developing processes. In theoretical and experimental studies of acoustic emission signals when searching for patterns in their parameter changes and developing methods for monitoring or diagnosing the state of composite materials, the problem lies in the interpretation of recorded information. This issue arises from the complexity and diversity of processes occurring in the material structure at micro and macro levels, and the high sensitivity of the acoustic emission method to these processes, wherein structural changes lead to observable alterations in the characteristics of acoustic emissions. Solving this problem requires both theoretical and experimental studies to understand the influence of various factors on the characteristics of the generated acoustic emission. The results of the presented study can be used to assess the condition of composite materials and structures, such as bridges, e.g., in terms of defectiveness, property dispersion, damage during operation, and other characteristics.
The proposed methodology aims to determine and forecast the technical condition of bridge elements, which could serve as an advanced engineering tool for assessing reliability and durability. It is ...developed based on fundamental studies that synthesize the experience of studying the physical–mechanical and physical–chemical properties of materials in bridge structures operating under real conditions. The theoretical foundation of the methodology is a reliability model and residual lifetime prediction of bridge elements based on Markov’s theory. The developed methodology is designed for assessing the technical condition of individual bridge elements, followed by a comprehensive evaluation of the entire structure. Reliability during operation is adopted as the indicator of technical condition. This quantitative reliability indicator in the model serves as a criterion for evaluating the safety level of bridge elements; ranking of bridge elements as necessary for specific types of repair, reconstruction, or replacement; strategic planning of expenditures for repair or reconstruction under limited funding; and forecasting the remaining resource of elements. An evaluation and prediction algorithm for the technical condition of bridges is proposed for the application of the developed methodology. A mathematical experiment of the developed methodology was conducted, which confirmed the adequacy of the proposed hypothesis, i.e., the use of the reliability model and the prediction of residual lifetime of bridge elements. First, a three-step mechanism for refining the technical condition of the bridge is proposed, significantly enhancing the accuracy of the calculations. Therefore, the developed methodology holds practical value and can serve as a basis for information-analytical systems for managing the condition of bridges.
The paper employs the particle swarm optimization (PSO) method for the identification of damage to a stringer web. This method is inspired by a swarm of bees or flock of birds which look for a common ...solution. It is a heuristic method, that utilizes a particle as a problem-solving candidate. The location of this particle in the search space represents the configuration of all the variables to possible solutions of the problem. As the particle moves into the solution space, the values of the variables change. The particle is defined by a position vector and a velocity vector. The resulting direction of the particle is determined by three components i.e. (1) the moment or inertia, (2) autobiographical or cognitive information and (3) social interaction. The quality of the particle is evaluated by a comparison function.
In this study we tried to locate damage by using this method. The damage is represented by a rusted area on a stringer web, which was simulated as a change in the Young’s modulus. We used the modal calculation of the eigenfrequencies as an evaluation function.
•Novel cyclic testing was devised for full-scale low aspect ratio RC walls in shear.•Hysteretic work diagrams, energy dissipation and damping ratios were assessed.•Shear strength of the wall was ...evaluated using advanced analysis and code formulae.•A nonlinear mathematical hysteresis model of the investigated walls is presented.
The unpredictable consequences of earthquakes have proven the necessity to study the shear mechanism of low-rise reinforced concrete walls further. Experimental testing remains the preferred approach to gather insight into the workings of the material and structural elements as the complex behavior of reinforced concrete does not lend itself to widely applicable generalized solutions. The contribution deals with cyclic testing of full-scale low aspect ratio reinforced concrete walls in a principally uniform shear state. An approach with various novel aspects in testing massive specimens is introduced. The obtained data was analyzed resulting in well-defined hysteresis curves. Characteristics of ultimate shear capacity, energy dissipation, damping and nonlinear effects are discussed. It was found that the sequence of load cycle amplitudes at the quasi-static rate does not significantly influence ultimate strength or overall behavior of the wall. Yet, hysteretic damping ratios depend on loading history and range from values considerably higher than commonly assumed in design to values that are lower. An advanced shear strength calculation is presented to relate the findings to previous research. A nonlinear mathematical model is described which is capable of simulating the hysteresis of the tested shear walls. The reported developments are applicable in design of structures.
The studying the dynamic response of steel-concrete railway bridges of Langer type is huge importance of ensuring the safety of such structures under high-speed train loads. Numerical simulations at ...the design stage require knowledge of the modal characteristics: natural frequencies, shapes and damping. In addition, in the dynamics of railway bridges subjected to high-speed trains, it is important to check the impact of dynamic effects on the ultimate and serviceability limit states. As part of the investigations displacements and accelerations of selected measurement points arising from driving the test rolling stock are analyzed. In the first stage, calculations of the eigenvalues and the corresponding eigenvectors were carried out in the Robot program for two variants of mass description (distributed and discrete). In the second stage, dynamic train passages for various vehicle speeds were examined in terms of displacements and accelerations of measurement points by using the authors’ program MES3D.
In Italy many important dams were built around the 1950s and 1960s, and now they have reached the critical age of 60 to 70 years of service during which a correct evaluation of their condition is of ...the highest importance with respect to public safety. For this reason, one of the most important and actual challenges in the field of civil engineering infrastructures concerns the development of health monitoring procedures that are able to give real-time knowledge of a critical condition possibly occurring in a dam structure.
In this study, an interpretative procedure is applied to the monitoring data of the Mignano Dam
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(Piacenza, Italy), to detect possible anomalies of the elastic structural behaviour.
Initially the sizable data collection presented a challenge of focus as to which aspect of the dam's behaviour was leading. Multiple takes had to be performed to develop a feel for structure and data. This led to a suite of parallel analyses, which came together in the end presenting a holistic picture.
The work aims at understanding the unique influences of external variables on the evolution of the horizontal displacement of the dam's crest. Numerical simulations indeed allow for quantifying the amount of displacement due to hydrostatical pressure and thermal load.
At first, a check of the field data is performed in order to assess the quality of the database and to avoid using corrupted signals. Subsequently, a stochastic model is created and several finite element analyses are described. Particular attention is given to the coupled field thermal-structural transient analysis in which all the available monitoring data are implemented.
Eventually a very satisfactory estimation of the dam's displacement is reached. The obtained methodology is able to efficiently predict the consequences of new load combinations and environmental changes on the dam. In future applications the presented assessment can be proficiently applied in real-time, for a direct interpretation of the structure's condition.
Different types of impermeable fillers are usually incorporated into polymeric coating film to enhance the gas barrier properties. For instance, impermeable fillers are commonly used in barrier ...coating due to their larger surface, which in turn serve as barrier inclusions restricting the penetrant gas to diffuse through a longer tortuous pathway. Modeling gas transport in barrier coating can help determine the shelf-life of packaged food and reduce product development resources and time. In this paper, related tortuosity-based models corresponding to different filler geometries are outlined. This review emphasizes the emerging trends in modeling the tortuous pathway and the respective relative permeability model to predict the gas barrier performance in composite films used for barrier coating applications. We review models incorporating a range of factors, including different shapes, geometries, angular orientations, alignments, randomness in distribution, stacking, interspacing, and the polydispersity of fillers. The approaches employed to develop the tortuosity-based phenomenological models starting with simplified filler geometry and orientations to more complex morphological features of the composite films are elaborated.
The presence of the crystalline regions in poly(vinyl alcohol) coating films acts as barrier clusters forcing the gas molecules to diffuse in a longer pathway in the amorphous region of the polymer, ...where diffusivity and solubility are promoted in comparison. Evaluating the influence of crystalline regions on the oxygen barrier property of a semi-crystalline polymer is thus essential to prepare better coating films. Poly(vinyl alcohol) coating films with varying induced crystallinity were prepared on a polyethylene terephthalate (PET) substrate by drying at different annealing temperatures for 10 min. The coating films were first delaminated from the PET substrate and then characterized using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction (XRD) techniques to determine and confirm the induced percentage of crystallinity. The barrier performance of the coating films, i.e., the oxygen transmission rate (OTR), was measured at room temperature. Results showed a decrease in the OTR values of poly(vinyl alcohol) film with an increase in the degree of crystallinity of the polymer matrix. Tortuosity-based models, i.e., modified Nielsen models, were adopted to predict the barrier property of the semi-crystalline PVOH film with uniform or randomly distributed crystallites. A modified Nielsen model for orderly distributed crystallites with an aspect ratio of 3.4 and for randomly distributed crystallites with an aspect ratio of 10.4 resulted in a good correlation with the experimental observation. For the randomly distributed crystallites, lower absolute average relative errors of 4.66, 4.45, and 5.79% were observed as compared to orderly distributed crystallites when the degree of crystallinity was obtained using FTIR, DSC, and XRD data, respectively.
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