Vibration and Acoustic Analysis of Trussed Railroad Bridge Under Moving Loads

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
R. Daniel Costley ◽  
Henry Diaz-Alvarez ◽  
Mihan H. McKenna ◽  
Anna M. Jordan
Keyword(s):  
Structural Damage ◽  
Acoustic Analysis ◽  
Current Model ◽  
Vehicle Suspension ◽  
Fe Model ◽  
Vibrational Modes ◽  
Moving Loads ◽  
Vehicle Loading ◽  
Vibration Responses ◽  
Railroad Bridge

A finite element (FE) model was developed for a Pratt truss railroad bridge located at Ft. Leonard Wood, MO. This model was used to investigate the vibration responses of a bridge under vehicle loading. Modeling results were obtained for a single axle with two wheels traversing the bridge at different speeds. The current model does not include the effects of vehicle suspension. Superposition of multiple axles was used to represent a locomotive transiting the bridge. The output of the vibration response was used as an input to an acoustic FE model to determine which vibrational modes radiate infrasound. The vibration and acoustic models of the railroad bridge will be reviewed, and results from the analysis will be presented. Measurements from an accelerometer mounted on the bridge agree reasonably well with model results. Infrasound could potentially be used to remotely provide information on the capacity and number of vehicles traversing the bridge and to monitor the bridge for significant structural damage.

Vibrational and Acoustical Analysis of Trussed Railroad Bridge Under Moving Loads

2012 ◽  
Author(s):  
R. Daniel Costley ◽  
Henry Diaz-Alvarez ◽  
Mihan H. McKenna
Keyword(s):  
Structural Damage ◽  
Current Model ◽  
Element Model ◽  
Vehicle Suspension ◽  
Fe Model ◽  
Vibrational Modes ◽  
Moving Loads ◽  
Vehicle Loading ◽  
Vibration Responses ◽  
Railroad Bridge

A Finite Element model has been developed for a Pratt truss railroad bridge located at Ft. Leonard Wood, MO. This model was used to investigate the vibration responses of a bridge under vehicle loading. Modeling results have been obtained for a single axle with two wheels traversing the bridge at different speeds. The current model does not include the effects of vehicle suspension. Superposition of multiple axles has been used to represent a locomotive transiting the bridge. The output of the vibration response was used as an input to an acoustic FE model to determine which vibrational modes radiate infrasound. The vibration and acoustic models of the railroad bridge will be reviewed, and results from the analysis will be presented. Measurements from an accelerometer mounted on the bridge agree reasonably well with model results. Infrasound could potentially be used to remotely provide information on the capacity and number of the vehicles traversing the bridge and to monitor the bridge for significant structural damage.

scholarly journals Damage Diagnosis in 3D Structures Using a Novel Hybrid Multiobjective Optimization and FE Model Updating Framework

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Nizar Faisal Alkayem ◽  
Maosen Cao ◽  
Minvydas Ragulskis
Keyword(s):  
Structural Damage ◽  
Model Updating ◽  
Complex Problem ◽  
Dynamic Responses ◽  
Mode Shapes ◽  
Fe Model ◽  
Modal Strain Energy ◽  
3D Structures ◽  
Multiobjective Particle Swarm Optimization ◽  
Damage Tracking

Structural damage detection is a well-known engineering inverse problem in which the extracting of damage information from the dynamic responses of the structure is considered a complex problem. Within that area, the damage tracking in 3D structures is evaluated as a more complex and difficult task. Swarm intelligence and evolutionary algorithms (EAs) can be well adapted for solving the problem. For this purpose, a hybrid elitist-guided search combining a multiobjective particle swarm optimization (MOPSO), Lévy flights (LFs), and the technique for the order of preference by similarity to ideal solution (TOPSIS) is evolved in this work. Modal characteristics are employed to develop the objective function by considering two subobjectives, namely, modal strain energy (MSTE) and mode shape (MS) subobjectives. The proposed framework is tested using a well-known benchmark model. The overall strong performance of the suggested method is maintained even under noisy conditions and in the case of incomplete mode shapes.

A Multi-State Strategy for Structural Damage Detection Using Sensitivity of Weighted Transmissibility Function

2021 ◽  
pp. 2150144
Author(s):  
Ziwei Luo ◽  
Huanlin Liu ◽  
Ling Yu
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Model Updating ◽  
Structural Parameters ◽  
Experimental Studies ◽  
Fe Model ◽  
Limited Information ◽  
Structural Damage Detection ◽  
State Strategy ◽  
Output Only

In practice, a model-based structural damage detection (SDD) method is helpful for locating and quantifying damages with the aid of reasonable finite element (FE) model. However, only limited information in single or two structural states is often used for model updating in existing studies, which is not reasonable enough to represent real structures. Meanwhile, as an output-only damage indicator, transmissibility function (TF) is proven to be effective for SDD, but it is not sensitive enough to change in structural parameters. Therefore, a multi-state strategy based on weighted TF (WTF) is proposed to improve sensitivity of TF to change in parameters and in order to further obtain a more reasonable FE model for SDD in this study. First, WTF is defined by TF weighted with element stiffness matrix, and relationships between WTFs and change in structural parameters are established based on sensitivity analysis. Then, a multi-state strategy is proposed to obtain multiple structural states, which is used to reasonably update the FE model and detect structural damages. Meanwhile, due to fabrication errors, a two-stage scheme is adopted to reduce the global and local discrepancy between the real structure and the FE model. Further, the [Formula: see text]-norm and the [Formula: see text]-norm regularization techniques are, respectively, introduced for both model updating and SDD problems by considering the characteristics of problems. Finally, the effectiveness of the proposed method is verified by a simply supported beam in numerical simulations and a six-storey frame in laboratory. From the simulation results, it can be seen that the sensitivity to structural damages can be improved by the definition of WTF. For the experimental studies, compared with the FE model updated from the single structural state, the FE model obtained by the multi-state strategy has an ability to more reasonably describe the change of states in the frame. Moreover, for the given structural damages, the proposed method can detect damage locations and degrees accurately, which shows the validity of the proposed method and the reliability of the updated FE model.

Local Mass Addition and Data Fusion for Structural Damage Identification Using Approximate Models

2020 ◽  
Vol 20 (11) ◽  
pp. 2050124
Author(s):  
Jilin Hou ◽  
Zhenkun Li ◽  
Qingxia Zhang ◽  
Łukasz Jankowski ◽  
Haibin Zhang
Keyword(s):  
Data Fusion ◽  
Objective Function ◽  
Structural Damage ◽  
Damage Identification ◽  
Structural Parameters ◽  
Identification Accuracy ◽  
Fe Model ◽  
Local Damage ◽  
Approximate Models ◽  
Structural Damage Identification

In practical civil engineering, structural damage identification is difficult to implement due to the shortage of measured modal information and the influence of noise. Furthermore, typical damage identification methods generally rely on a precise Finite Element (FE) model of the monitored structure. Pointwise mass alterations of the structure can effectively improve the quantity and sensitivity of the measured data, while the data fusion methods can adequately utilize various kinds of data and identification results. This paper proposes a damage identification method that requires only approximate FE models and combines the advantages of pointwise mass additions and data fusion. First, an additional mass is placed at different positions throughout the structure to collect the dynamic response and obtain the corresponding modal information. The resulting relation between natural frequencies and the position of the added mass is sensitive to local damage, and it is thus utilized to form a new objective function based on the modal assurance criterion (MAC) and [Formula: see text]-based sparsity promotion. The proposed objective function is mostly insensitive to global structural parameters, but remains sensitive to local damage. Several approximate FE models are then established and separately used to identify the damage of the structure, and then the Dempster–Shafer method of data fusion is applied to fuse the results from all the approximate models. Finally, fractional data fusion is proposed to combine the results according to the parametric probability distribution of the approximate FE models, which allows the natural weight of each approximate model to be determined for the fusion process. Such an approach circumvents the need for a precise FE model, which is usually not easy to obtain in real application, and thus enhances the practical applicability of the proposed method, while maintaining the damage identification accuracy. The proposed approach is verified numerically and experimentally. Numerical simulations of a simply supported beam and a long-span bridge confirm that it can be used for damage identification, including a single damage and multiple damages, with a high accuracy. Finally, an experiment of a cantilever beam is successfully performed.

Two-Stage Structural Damage Assessment by Combining Modal Kinetic Energy Change with Symbiotic Organisms Search

2019 ◽  
Vol 19 (10) ◽  
pp. 1950120 ◽  
Author(s):  
D. Dinh-Cong ◽  
T. Nguyen-Thoi ◽  
M. Vinyas ◽  
Duc T. Nguyen
Keyword(s):  
Kinetic Energy ◽  
Damage Assessment ◽  
Structural Damage ◽  
Heuristic Algorithms ◽  
Computational Cost ◽  
Energy Change ◽  
Fe Model ◽  
Two Stage ◽  
Symbiotic Organisms Search ◽  
Symbiotic Organisms

In the literature, modal kinetic energy (MKE) has been commonly utilized for optimal sensor placement strategies. However, there have been very few studies on its application to structural damage detection. This paper introduces a new two-stage structural damage assessment method by combining the modal kinetic energy change ratio (MKECR) and symbiotic organisms search (SOS) algorithm. In the first stage, an efficient damage indicator, named MKECR, is used to locate the potential damaged sites. Meanwhile, for the purpose of comparison with MKECR, three other indices are also used. In the second stage, an SOS-based finite element (FE) model updating strategy is adopted to estimate the damage magnitude of identified sites, while excluding false warnings (if any), where an objective function is proposed using a combination of the flexibility matrix and modal assurance criterion (MAC). The performance of the SOS algorithm is also verified by comparing with four other meta-heuristic algorithms. Finally, three numerical examples of 2D truss and frame structures with various hypothetical damage scenarios are carried out to investigate the capability of the proposed method. The numerical results indicate that the proposed method not only can accurately locate and quantify single- and multi-damage in the structures, but also shows a great saving in computational cost.

Effect of Burner and Resonator Impedances on the Acoustic Behavior of Annular Combustion Chambers

2006 ◽  
Author(s):  
Annalisa Forte ◽  
Sergio Camporeale ◽  
Bernardo Fortunato ◽  
Francesca Di Bisceglie ◽  
Marco Mastrovito
Keyword(s):  
Numerical Simulations ◽  
Combustion Chamber ◽  
Structural Damage ◽  
Acoustic Pressure ◽  
Acoustic Analysis ◽  
Complex Geometry ◽  
Connected Components ◽  
Acoustic Behavior ◽  
Combustion Chambers ◽  
Helmholtz Resonators

Premixed combustion is the commonly adopted technique to reduce NOx emissions from gas turbine combustion chambers, but it has been proved to be susceptible to thermo-acoustic instabilities, known as humming. These self-excited oscillations can reduce the efficiency of the turbine and generate structural damage to the combustion chamber. One of the proposed suppression methods lies in the application of Helmholtz resonators to the combustion chambers. This passive technique is advantageous in carrying out appreciable oscillation damping with modest costs and long life, but it is effective only in a restricted range of frequency, close to resonator eigenfrequency. Therefore, in order to design effective resonators, it is necessary to know the eigenfrequencies of the annular combustion chamber, because combustion instabilities arise in correspondence of these frequencies. Acoustic analysis of combustion chamber and its connected components may be carried out by means of Finite Element Method, but it requires a considerable computational effort due to the complex geometry of the complete system, which needs to be meshed by a refined grid. A combined numerical and experimental technique allows the authors to increase computational efficiency by adopting coarser and more regular meshes. First acoustic behavior of annular combustion chamber has been studied by means of numerical simulations and, therefore, the influence of the burners has been taken into account by substituting burner geometries by experimentally measured acoustic impedances. Then some Helmholtz resonators, tuned to one eigenfrequency of the combustion chamber, have been designed and manufactured. Their acoustic impedances have been experimentally measured and applied as boundary conditions into FE simulations of the annular chamber. In this way the acoustic pressure field inside the damper-equipped combustion chamber has been analyzed. Numerical simulations of the annular chamber, with burner and damper impedances applied, show that Helmholtz resonators are effective in oscillation suppression in correspondence of their resonance frequency, but may produce the splitting of the acoustic pressure peak of the chamber into two new peaks, whose frequencies lie on either side of the original common eigenfrequency. The amplitudes of these two new pressure peaks appear lower than the amplitude of the baseline one. The proposed technique can be used as an effective design tool: acoustic analysis of annular combustion chamber, with burner impedance applied, produces accurate indications about its acoustic behavior and allows the design of new passive suppression systems and the evaluation of their performances.

Review and Prospect on Dynamic FE Model Updating Methods of Footbridge Structures Based on Ambient Excitation

2011 ◽  
Vol 291-294 ◽  
pp. 1572-1577
Author(s):  
Rui Zhao ◽  
Yi Gang Zhang
Keyword(s):  
Structural Damage ◽  
Optimization Design ◽  
Damage Identification ◽  
Model Updating ◽  
Target Function ◽  
Optimization Theory ◽  
Empirical Method ◽  
Fe Model ◽  
Fe Model Updating ◽  
Ambient Excitation

The discrete finite element (FE) model often cannot reflect structure characteristics accurately due to imply more idealistic assumptions and simplifications. Therefore, it is necessary to update FE model for structural damage identification, response calculation, safety evaluation, optimization design, and so on. This article will illustrate respectively three key steps of updating parameters selection, target function selection and optimization method in process of dynamic FE model updating of footbridge structures based on ambient excitation, and put forward a feasible updating method: combine empirical method with sensitivity analysis method to select updating parameters; joint natural frequencies, MAC and modal flexibility as target function; adopt optimization algorithm based on the optimization theory.

Damage Detection Based on the Cross Correlation Function Amplitude Vector and its Application to the ASCE Benchmark Structure

2007 ◽  
Vol 353-358 ◽  
pp. 2317-2320 ◽  
Author(s):  
Zhe Feng Yu ◽  
Zhi Chun Yang
Keyword(s):  
Correlation Function ◽  
Damage Detection ◽  
Structural Damage ◽  
Cross Correlation ◽  
Relative Difference ◽  
Random Excitation ◽  
Cross Correlation Function ◽  
Vibration Responses ◽  
Specific Frequency ◽  
The Cross

A new method for structural damage detection based on the Cross Correlation Function Amplitude Vector (CorV) of the measured vibration responses is presented. Under a stationary random excitation with a specific frequency spectrum, the CorV of the structure only depends on the frequency response function matrix of the structure, so the normalized CorV has a specific shape. Thus the damage can be detected and located with the correlativity and the relative difference between CorVs of the intact and damaged structures. With the benchmark problem sponsored by ASCE Task Group on Structural Health Monitoring, the CorV is proved an effective approach to detecting the damage in structures subject to random excitations.

scholarly journals A Steel-Concrete Composite Beam Element for Structural Damage Identification

2020 ◽  
Vol 20 (10) ◽  
pp. 2042015
Author(s):  
Faraz Sadeghi ◽  
Jianchun Li ◽  
Xinqun Zhu
Keyword(s):  
Composite Beam ◽  
Composite Structures ◽  
Structural Damage ◽  
Damage Identification ◽  
Beam Element ◽  
Bonding Interface ◽  
Fe Model ◽  
Static Responses ◽  
Structural Damage Identification ◽  
Interface Layers

The composite action between the layers of steel and concrete is governed by the shear connection. Because of the complicated interconnection behavior of these composite layers, it is difficult to detect damage in the composite structures, especially, the interfacial integrity of the two layers. In this paper, anovel method has been developed for structural damage identification of composite structures based on a steel-concrete composite beam element with bonding interface. In displacement-based finite element (FE) formulation, three damage indicators have been embedded into stiffness matrix of the composite beam that are defined as a stiffness reduction in the concrete, steel and interface layers. An algorithm-based on recursive quadratic programming has been proposed to identify structural damage in the composite beam from static measurements. The analytical FE model is validated by adapting its static responses in undamaged state with those obtained from an equal experimental model as well as a FE model developed in commercial software ABAQUS. A convergence study is conducted to determine the number of the composite beam FEs. To verify the proposed method, the static responses of the FE model with different damage cases at a given loading are calculated, and the measurements are simulated by adding different levels of white noise. Then, the proposed algorithm is applied to identify damage of the composite beam. The effects of measurement noise, loading location and amplitude, measurement numbers and the sizes of FE mesh on the identified results have been investigated. The numerical results show that this method is efficient and accurate to separately identify small damage in the concrete slab, and the steel girder and bonding interface of the composite beam.

Multi-Objective Model Updating Optimization Considering Orthogonality

2019 ◽  
Vol 14 (6) ◽  
Author(s):  
Braden T. Warwick ◽  
Il Yong Kim ◽  
Chris K. Mechefske
Keyword(s):  
Mode Shape ◽  
Degrees Of Freedom ◽  
Pareto Front ◽  
Model Updating ◽  
Current Model ◽  
Physical Reality ◽  
Frequency Error ◽  
Fe Model ◽  
Multi Objective ◽  
Objective Model

The coordinate orthogonality check (CORTHOG) and multi-objective optimization considering pseudo-orthogonality as an objective function are introduced to overcome several limitations present in current model updating methods. It was observed that the use of the CORTHOG to remove four inaccurate degrees-of-freedom (DOF) was able to increase the orthogonality between mode shape vectors. The multi-objective model updating process generated a Pareto front with 38 unique optimal solutions. Four critical points were identified along the Pareto front, of which decreased the natural frequency error by greater than 2.84% and further increased the orthogonality between mode shape vectors. Therefore, it has been demonstrated that both steps of the methodology are critical to significantly reduce the overall errors of the system and to generate a finite element (FE) model that best describes physical reality. Additionally, the methodology introduced in this work generated a feasible computational runtime allowing for it to be easily adapted to widespread applications.

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