scholarly journals Damage Detection of Truss Structures by Reduction of Degrees of Freedom Using the Serep Method

2020 ◽  
Vol 15 (1) ◽  
pp. 1-25
Author(s):  
Shahin Lale Arefi ◽  
Amin Gholizad
Keyword(s):  
Damage Detection ◽  
Degrees Of Freedom ◽  
Truss Structures ◽  
Modal Strain Energy ◽  
Modal Strain Energy Method ◽  
Bridge Structures ◽  
Operating Lifetime ◽  
Equivalent Reduction ◽  
Proper Performance ◽  
Process Method

Damage detection of bridge structures during their operating lifetime is essential. In this paper, two approaches, All Degrees of Freedom and Reduction of the Degrees of Freedom methods, are used to detect the damages in structures. The first method considers All Degrees of Freedom of the structure and the second method, Reduction of the Degrees of Freedom. Since the sensors are installed only on a few degrees of freedom, the responses are available for some of them. The Degrees of Freedom must be reduced and System Equivalent Reduction Expansion Process method is one of the most efficient ways to solve the problem. This research aimed to identify the damage of structures using the Modal Strain Energy method by reducing the structural degree of freedom. Two standard examples are used and the results compared to different damage cases to examine the efficiency of the mentioned method. The results illustrated the proper performance of the Reduction of the Degrees of Freedom method to identify the damage in truss structures. By increasing the number of modes, Reduction of the Degrees of Freedom method detects considerably more accurate the damaged elements, especially when the noise is considered. Also, based on the outcomes to identify damaged elements, it is possible to consider more modes instead of more sensors.

An effective method for damage assessment based on limited measured locations in skeletal structures

2020 ◽  
Vol 24 (1) ◽  
pp. 183-195 ◽  
Author(s):  
Parsa Ghannadi ◽  
Seyed Sina Kourehli
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Damage Detection ◽  
Degrees Of Freedom ◽  
Truss Structures ◽  
Mode Shapes ◽  
Analysis Model ◽  
Test Analysis ◽  
Modal Test ◽  
Artificial Neural

This article proposes a new damage detection method using Modal Test Analysis Model and artificial neural networks. A challenge in damage detection problems is lack of measured degrees of freedom, as well as limitations of attached sensors. Modal Test Analysis Model has been used in order to estimate unmeasured degrees of freedom. An experimental cantilever beam was used to show Modal Test Analysis Model’s efficiency in estimation of unmeasured mode shapes. To solve the inverse problem of damage detection, mode shapes estimated by Modal Test Analysis Model were used as inputs, and characteristics of the damage served as outputs of the artificial neural network. The sensitivity analysis carried out for each example showing the performance of artificial neural network after mode shape expansion was efficiently improved. Three numerical examples for plane and space truss structures are considered, in order to verify effectiveness of the proposed method. Results demonstrate a high accuracy of Modal Test Analysis Model and artificial neural network for structural damage detection.

scholarly journals Disassembling-Based Structural Damage Detection Using Static Measurement Data

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Eun-Taik Lee ◽  
Hee-Chang Eun
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Degrees Of Freedom ◽  
Measurement Data ◽  
Truss Structures ◽  
Detection Methods ◽  
Internal Stresses ◽  
Structural Damage Detection ◽  
Constraint Forces ◽  
Entire Structure

Damage detection methods can be classified into global and local approaches depending on the division of measurement locations in a structure. The former utilizes measurement data at all degrees of freedom (DOFs) for structural damage detection, while the latter utilizes data of members and substructures at a few DOFs. This paper presents a local method to detect damages by disassembling an entire structure into members. The constraint forces acting at the measured DOFs of the disassembled elements at the damaged state, and their internal stresses, are predicted. The proposed method detects locally damaged members of the entire structure by comparing the stress variations before and after damage. The static local damage can be explicitly detected when it is positioned along the constraint load paths. The validity of the proposed method is illustrated through the damage detection of two truss structures, and the disassembling (i.e., local) and global approaches are compared using numerical examples. The numerical applications consider the noise effect and single and multiple damage cases, including vertical, diagonal, and chord members of truss structures.

scholarly journals Clustering Elements of Truss Structures for Damage Identification by CBO

2020 ◽  
Author(s):  
Mohammad Hosein Talebpour ◽  
Younes Goudarzi ◽  
Mehrdad Sharifnezhad
Keyword(s):  
Damage Detection ◽  
Damage Identification ◽  
Dynamic Properties ◽  
Heuristic Method ◽  
Search Space ◽  
Truss Structures ◽  
Local Optimum ◽  
Structural Elements ◽  
Modal Strain Energy ◽  
Damage Location

The number of structural elements plays a significant role in detecting damage location and severity; such methods have sometimes failed to provide correct solutions due to the entrapment of damage detection algorithms in the local optimum. To resolve this problem, this study proposed the simultaneous use of mathematical and statistical methods to narrow down the search space. To this end, a two-step damage detection method was proposed. In the first step, the structural elements were initially divided into different clusters using the k-means method. Subsequently, the possibly damaged elements of each cluster were identified. In the second step, the elements selected in the first step were placed in a new set, and a process was applied to identify their respective damage location and severity. Thus, the proposed method reduced the search space as well as the possibility of entrapment in the local optimum. Other advantages of the proposed method include the use of fewer dynamic properties. Accordingly, by narrowing down the search space and the dimensions of the system for governing equations, the proposed method could significantly increase the chance of obtaining favorable results in structures with many elements and those with few vibration modes. A meta-heuristic method, called the colliding bodies optimization (CBO), was used in the proposed damage detection optimization algorithm. The optimization problem was based on the modal strain energy equations. According to the results, the proposed method was able to detect the location and severity of damage, even at its slightest percentage.

Research on Two-Step Damage Detection Method for Complex Gird Truss Structure under Wind Load

2012 ◽  
Vol 256-259 ◽  
pp. 1131-1138
Author(s):  
Hui Liu ◽  
Xue Liang Wang ◽  
Wei Lian Qu
Keyword(s):  
Spectral Density ◽  
Damage Detection ◽  
Power Spectral Density ◽  
Detection Method ◽  
Damage Index ◽  
Truss Structure ◽  
Truss Structures ◽  
Detection Methods ◽  
Modal Strain Energy ◽  
Power Spectral

Considering characteristics of gird truss structure, the suitable two-step damage detection method for these structures is proposed in the paper. The acceleration power spectral density sensibility of structural nodes is obtained by analyzing their acceleration power spectral density value caused every damaged structural bar. According to sensibility value, the range of influence of damaged structural bar is determined, then structural sub regions are divided and accelerators are distributed. The first step damage detection methods is identifying damaged bar occurrence region, it is extracting damage index to identify the damage occurrence region based on changes of acceleration response power spectral density of structure damaged after and before. The second step damage detection methods is located damaged bar in the region, it is completed by finding the damaged bar based on the theory of dissipation ratio of modal strain energy damage detection method. At last, taking the gird truss structure as numerical example, it shows the method has the capability to detect the damage of complex gird truss structures successfully.

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