Experimental research and finite element analysis on the dynamic characteristics of concrete steel bridges with multi-cracks
TL;DR: In this paper, the authors considered the high-order vibration characteristics of structures with multi-cracks and established finite element models for concrete steel beam and bridge with cracks under three different conditions and obtained vibration frequency and three order modes through simulation.
Abstract: Complex bridges will inevitably have cracks in operation. Dynamic characteristics with crack structures have been researched central issues. In the past, few researches were conducted from the whole structure of bridges with multi-cracks. In the meanwhile, related experimental research and systematic numerical simulation were lacking. In addition, researches on cracks seldom considered the high-order vibration characteristics of structures with multi-cracks. Aimed at this problem, this paper selected the whole bridge structure which was widely applied in engineering to study dynamic characteristics. For the concrete steel bridge with two cracks, this paper established finite element models for concrete steel beam and bridge with cracks under three different conditions and obtained vibration frequency and three order modes through simulation. Then, this paper analyzed and verified the correctness of numerical simulation result through experiment. Based on the verified model, this paper conducted a systematic analysis and summary, and obtained the following findings: The vibration frequency of concrete steel beams with cracks was obviously affected by cracks. The higher the order was, the greater the impact of cracks on frequency would be and the smaller the impact of cracks on the amplitude of modes would be. With the increased crack depth, the impact on the vibration frequency of concrete steel beams was more obvious. Additionally, crack distance also had some impacts on the dynamic characteristics of concrete steel beams. Numerical simulation model and method in this paper provided foundation and reference for continuing to analyze concrete steel beams with other crack forms or other structural forms. In the meanwhile, the three-dimensional analytical contour in this paper could help engineers to more intuitively understand and valuably apply the change rule of impact of crack depth and position on concrete steel beams.
Citations
More filters
TL;DR: To solve the low attack path quantification degree and complex path finding in the industrial Internet of Things, a vulnerability assessment method based on attack graph and maximum flow is proposed.
Abstract: To solve the low attack path quantification degree and complex path finding in the industrial Internet of Things, a vulnerability assessment method based on attack graph and maximum flow is proposed. The method takes into account the factors influencing the attack behavior and relationship between network nodes. The attack risk is calculated by common vulnerability scoring system, which increases the attack path quantification degree. The maximum loss flow describes the attack path, evaluates the network vulnerability by maximum loss flow and loss saturation and represents the vulnerability relevance. Avoiding the repeat calculation and obtaining the potential key vulnerability path fast, the augmented road algorithm is used to find optimal attack path within global path. The result shows that the method is feasible and can evaluate the vulnerability and risk path objectively.
90 citations
Cites methods from "Experimental research and finite el..."
...In literature [8], built the relationship between vulnerabilities by using the idea of Bayesian network separation, proposed a vulnerability assessment method based on Bayesian network....
[...]
TL;DR: This paper introduces a novel feature selection approach based on potential entropy evaluation criteria (FMPE) and shows that the FMPE algorithm can effectively eliminate the unimportant features or noise features to improve the performance of the classification algorithm.
Abstract: In recent years, with the rapid development of industrial Internet of Things, the rapid growth of data has become a severe challenge and precious opportunity faced by many industries. The information society has entered the era of big data. Feature selection is frequently used to reduce the number of features in many applications of Internet of things, where data of high dimensionality are involved. To the best of our knowledge, a fewer researchers focus on the physical distribution of data and the anisotropy of the data characteristics. To this end, this paper introduces a novel feature selection approach based on potential entropy evaluation criteria (FMPE). The FMPE method considers the distribution of the data itself when measuring the importance of the feature. The data is mapped into a high-dimensional space which has better divisibility by extending data field to generalized multidimensional data field. Related experiments and analyses on UCI data sets and face data sets show that the FMPE algorithm can effectively eliminate the unimportant features or noise features to improve the performance of the classification algorithm. A high classification accuracy is achieved by the combination of the selected feature subset and a variety of classifiers and the FMPE algorithm is independent of the specific classifier.
29 citations
Cites background from "Experimental research and finite el..."
...However, in the face of the electronic information of themultitude, they are at a loss, how to acquire the information we need is an urgent problem [32]....
[...]
TL;DR: A control strategy based on the flux density observer is proposed using an analysis of the working principle and the structure of the suspension system and an adaptive sliding mode controller is presented to reduce the upper bound of both uncertainty and interference of the sliding mode controllers.
Abstract: The control method and dynamic performance of a magnetic suspension system, which is the core component of maglev trains, have a significant influence on the performance of the maglev train. Currently, a control strategy based on the current feedback is widely used. However, the stable range of control parameters is relatively small, making it difficult to identify stable regions for the control parameters. In addition, the strong interactions between the control parameters are cause issues in the control. In this paper, a control strategy based on the flux density observer is proposed using an analysis of the working principle and the structure of the suspension system. A nonlinear dynamic model of a maglev system is established by utilizing the state equation of the flux feedback. Based on the current and voltage feedback, a hybrid magnetic flux density observer is presented. According to the mathematical model, an adaptive sliding mode controller is designed to reduce the upper bound of both uncertainty and interference of the sliding mode controller. Finally, a theoretical analysis and the effectiveness of the proposed control strategy are verified using both simulations and experiments.
28 citations
TL;DR: The results demonstrate that GeFeS can significantly generalize the proposed multi-population intelligent genetic algorithm under different sizes of two-class and multi-class datasets.
27 citations
Cites background from "Experimental research and finite el..."
...However, in the face of substantial digital information, an urgent challenge is how to acquire accurate information [2]....
[...]
References
More filters
TL;DR: In this article, a damage identification technique based on changes in frequencies and mode shapes of vibration is proposed for predicting damage location and severity, which is applied at an element level with a conventional finite-element model.
Abstract: The change of modal characteristics directly provides an indication of structural damage. Based on changes in frequencies and mode shapes of vibration, a damage identification technique is proposed in this paper for predicting damage location and severity. The method is applied at an element level with a conventional finite-element model. The element damage equations have been established through the eigenvalue equations that characterize the dynamic behavior. Several solution techniques are discussed and compared. The influence of simulated noise in the modal data is also presented. The method has been verified by a number of damage scenarios for simulated beams and has found the exact location and severity of damage. It is demonstrated that multiplying the damaged eigenvalue equations with the undamaged or damaged mode shapes provides more equations and guarantees the damage localization. The resulting equations, however, become more sensitive to the deviation of modal data and the direct solution often...
274 citations
"Experimental research and finite el..." refers background in this paper
...Generally speaking, the damage of structures will usually change the physical properties of structures, like mass, damping and stuffiness and cause changes in the dynamic characteristics of structures [3]....
[...]
TL;DR: In this article, free and forced vibration analysis of a cracked beam were performed in order to identify the crack in a cantilever beam, and the results suggest that free vibration analysis provides suitable information for the detection of single and two cracks, whereas forced vibration can detect only the single crack condition.
Abstract: Structures are weakened by cracks. When the crack size increases in course of time, the structure becomes weaker than its previous condition. Finally, the structure may breakdown due to a minute crack. Therefore, crack detection and classification is a very important issue. In this study, free and forced vibration analysis of a cracked beam were performed in order to identify the crack in a cantilever beam. Single- and two-edge cracks were evaluated. The study results suggest that free vibration analysis provides suitable information for the detection of single and two cracks, whereas forced vibration can detect only the single crack condition. However, dynamic response of the forced vibration better describes changes in crack depth and location than the free vibration in which the difference between natural frequencies corresponding to a change in crack depth and location only is a minor effect.
163 citations
"Experimental research and finite el..." refers methods in this paper
...Sadettin adopted the wavelet transform to solve and analyze the first-order vibration of the cantilever beam with cracks [14]....
[...]
01 Jul 2006
TL;DR: In this paper, the nonlinear output frequency response functions (NOFRFs) are used to detect cracks in beams using frequency domain information. But the results show that the NOFRFs are a sensitive indicator of the presence of cracks providing the excitation is of an appropriate strength.
Abstract: The new concept of Nonlinear Output Frequency Response Functions (NOFRFs) is introduced in this paper to detect cracks in beams using frequency domain information. The results show that the NOFRFs are a sensitive indicator of the presence of cracks providing the excitation is of an appropriate strength. The new results provide a novel and effective method for the detection of cracks in beams, with applications in structural fault diagnosis.
130 citations
"Experimental research and finite el..." refers background in this paper
...Peng adopted the assumed modal transformation to study the cantilever beam with cracks [15]....
[...]
TL;DR: In this article, nonlinear output frequency response functions (NOFRFs) are introduced to detect cracks in beams using frequency domain information, and the results show that the NOFRFs are a sensitive indicator of the presence of cracks providing the excitation is of an appropriate intensity.
128 citations
TL;DR: In this paper, the amplitude-dependent dynamic characteristics of functionally graded electrorheological (FGER) sandwich beams are investigated and the nonlinear fundamental frequency and modal loss factor ratio are extracted in different boundary conditions, applied electric fields, FGM volume fraction indices and thickness ratios.
26 citations