Damage identification in offshore jacket structures based on modal flexibility

2018 ◽  
Vol 170 ◽  
pp. 171-185 ◽  
Author(s):  
Kang Liu ◽  
Ren-Jun Yan ◽  
C. Guedes Soares
Keyword(s):  
Damage Identification ◽  
Modal Flexibility ◽  
Jacket Structures

A Novel Two-Stage Structural Damage Identification Method Based on Superposition of Modal Flexibility Curvature and Whale Optimization Algorithm

2021 ◽  
pp. 2150169
Author(s):  
Minshui Huang ◽  
Xihao Cheng ◽  
Zhigang Zhu ◽  
Jin Luo ◽  
Jianfeng Gu
Keyword(s):  
Optimization Algorithm ◽  
Damage Identification ◽  
Whale Optimization Algorithm ◽  
Two Stage ◽  
Simply Supported ◽  
Damage Location ◽  
Flexibility Matrix ◽  
Modal Flexibility ◽  
Whale Optimization ◽  
The Impact

A novel two-stage method is proposed to properly identify the location and severity of damage in plate structures. In the first stage, a superposition of modal flexibility curvature (SMFC) is adopted to locate the damage accurately, and the identification index of modal flexibility matrix is improved. The low-order modal parameters are used and a new column matrix is formed based on the modal flexibility matrix before and after the structure is damaged. The difference of modal flexibility matrix is obtained, which is used as a damage identification index. Meanwhile, based on SMFC, a method of weakening the “vicinity effect” is proposed to eliminate the impact of the surrounding elements to the damaged elements when damage identification is carried out for the plate-type structure. In the second stage, the objective function based on the flexibility matrix is constructed, and according to the damage location identified in the first stage, the actual damage severity is determined by the enhanced whale optimization algorithm (EWOA). In addition, the effects of 3% and 10% noise on damage location and severity estimation are also studied. By taking a simply supported beam and a four-side simply supported plate as examples, the results show that the method can accurately estimate the damage location and quantify the damage severity without noise. When considering noise, the increase of noise level will not affect the assessment of damage location, but the error of quantifying damage severity will increase. In addition, damage identification of a steel-concrete composite bridge (I-40 Bridge) under four damage cases is carried out, and the results show that the modified method can evaluate the damage location and quantify 5%–92% of the damage severity.

scholarly journals Damage Identification of Plate Structure Based on the Method of Modal Flexibility Curvature Difference

2019 ◽  
Vol 256 ◽  
pp. 02015
Author(s):  
Jiangang Zhao ◽  
Yuxiang Zhang ◽  
Jiazhao Chen
Keyword(s):  
Numerical Analysis ◽  
Lower Order ◽  
Damage Identification ◽  
Higher Order ◽  
Plate Structure ◽  
First Order ◽  
Flexibility Matrix ◽  
Damage Degree ◽  
Higher Order Modes ◽  
Modal Flexibility

According to the higher order modes of the structure are difficult to extract and the lower order are easy to obtain in practice, it is put forward that only uses the parameters of lower or first-order modal to constitute the modal flexibility curvature difference (MFCD) as the index of damage identification, which based on the flexibility matrix of structure being sensitive to the structure modal characteristics. Numerical analysis is made on different damage conditions of a plate structure, and the result shows that the MFCD can not only accurately identify the single-damage and multi-damage position of plate structure, but also reflect the size of damage degree. It has a great significance to apply the index into the range of damage identification of actual structures.

Damage Identification for Curl Tube Structure Based on Modal Flexibility Curvature

2012 ◽  
Vol 490-495 ◽  
pp. 2151-2155
Author(s):  
Yong Jun Li ◽  
Li Yuan Ma ◽  
Tian Hui Wang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Damage Identification ◽  
Vertical Plane ◽  
The Finite Element Method ◽  
Central Difference ◽  
Damage Location ◽  
Modal Flexibility ◽  
Central Difference Method ◽  
Tube Structure

To detect the damage of curl tube structure with more effect, the finite element method (FEM) and experimental modal analysis (EMA) were employeed to generate the modal flexibility of the curl tube. The modal flexibility was used to compute the modal flexibility-curvature by using the central difference method. Different degrees and locations of damage were simulated by additional quality in the intact curl tube to verify the modal flexibility-curvature and difference generated by both FEM and EMA. The results show that the modal flexibility of curl tube should have the direction. In addition, we conclude that the flexibility curvature’s difference in x and y plane can not be used for damage identification. But using the flexibility curvature’s difference of the z direction in the vertical plane, we can not only identified the multiple damage location, but also to analized degree for the extent of injury to the same location .

Study on Box Girder Damage Identification of Cable-Stayed Bridges

2011 ◽  
Vol 101-102 ◽  
pp. 1156-1160
Author(s):  
Hua Wei Zhu ◽  
Hong Mou Wang ◽  
Wei Peng
Keyword(s):  
Damage Identification ◽  
Stress Index ◽  
Bending Stress ◽  
Box Girder ◽  
Cable Tension ◽  
Flexibility Matrix ◽  
Tension Index ◽  
Modal Flexibility ◽  
Curvature Index ◽  
Modal Curvature

A comparative study of the girder damage identification of Jintang Cable-stayed Bridge in Zhoushan Island-Land Project using the deflection index, the cable tension index, the beam bottom bending stress index, the modal curvature index and the modal flexibility matrix is introduced. By means of finite element method, a series of damage cases associated with the box girder are analyzed. The result shows that, for different damage types, the best effect of the girder damage identification is the modal curvature index, followed by the cable tension index, the beam bottom bending stress index is nearly of the same effect as the modal flexibility matrix index, and the worst is the deflection index.

scholarly journals Locating and Quantifying Damage in Beam-like Structures Using Modal Flexibility-based Deflection Changes

2020 ◽  
Vol 20 (10) ◽  
pp. 2042008
Author(s):  
N. T. Le ◽  
A. Nguyen ◽  
D. P. Thambiratnam ◽  
T. H. T. Chan ◽  
T. Khuc
Keyword(s):  
Strain Energy ◽  
Damage Identification ◽  
Real Life ◽  
Detection Methods ◽  
Beam Model ◽  
Structural Components ◽  
Modal Strain Energy ◽  
Modal Flexibility ◽  
Modes Of Vibration ◽  
Identification Tool

This paper presents an enhanced method to locate and quantify damage in beam-like structures using changes in deflections estimated from modal flexibility (MF) matrices. The method is developed from explicit relationship between a series of MF-based deflection change vectors and the damage characteristics. Based on this, three damage locating criteria are defined and used to detect and locate damage. Once the damage is located, its severity is estimated conveniently from a closed-form function. The capability of the proposed method is examined through numerical and experimental verifications on a steel beam model. The result shows that the method accurately locates and quantifies damage under various scenarios using a few modes of vibration, with satisfactory or even better results compared to those obtained from traditional static deflection-based method. The performance of the proposed method is also compared with three well-known vibration-based damage detection methods using changes in MF and modal strain energy. It is found that the proposed method outperformed the other three methods, especially for multiple damage cases. As beams can represent various structural components, the proposed method provides a promising damage identification tool targeting the application to real-life structures.

Detection Indicator of Structural Nondestructive Damage Based on Flexibility Curvature Difference Rate

2015 ◽  
Vol 744-746 ◽  
pp. 46-52 ◽  
Author(s):  
Chang Sheng Xiang ◽  
Yu Zhou ◽  
Sheng Kui Di ◽  
Li Xian Wang ◽  
Jian Shu Cheng
Keyword(s):  
Structural Damage ◽  
Damage Identification ◽  
Continuous Beam ◽  
Change Rate ◽  
Modal Frequency ◽  
Numerical Examples ◽  
Modal Flexibility ◽  
Structural Damage Identification ◽  
Before And After ◽  
Better Than

Applied to the structural damage identification, Modal Flexibility is better than the Modal Frequency and Modal Displacement, the indicators of Flexibility Curvature are effective and sensitive. This paper proposes a new detection indicator which is Flexibility Curvature Difference Rate (FCDR) that by using the change rate of diagonal elements of flexibility curvature difference when before and after damage. The numerical examples of a simple beam, a continuous beam and a frame with the damage conditions of the different positions and different degrees are used to verify FCDR. The result shows that FCDR can well identify the numerical examples damages, and sensitively diagnose the damage near the supports of beam and the nodes of framework.

Research on Damage Identification of Cable-Stayed Bridge with Model Test Based on Dynamic Characteristics

2014 ◽  
Vol 501-504 ◽  
pp. 1228-1232
Author(s):  
Zhao Hui Lu ◽  
Wei Peng ◽  
Quan Hui Chang ◽  
Jian Guo ◽  
Lu Lu Wang
Keyword(s):  
Damage Identification ◽  
Damage Location ◽  
Cable Stayed Bridge ◽  
Placement Optimization ◽  
Damage Recognition ◽  
Sensor Placement Optimization ◽  
Modal Flexibility ◽  
Proper Number ◽  
Design And Manufacture ◽  
Different Parts

Based on the change coefficient of modal flexibility curvature, an experimental research on damage recognition of cable-stayed bridge was conducted. The working conditions are introduced, as well as the design and manufacture of the model that can serve as an important guide to the similar experiments. In the design of this experiment, the optimization of cable tensions and the sensor placement optimization were discussed and the suitable methods were chosen and verified. The results verify the sensitivity of the change coefficient of modal flexibility curvature and compare the identification ability on different parts of the same damage location. In addition, how the number of modes required affects the change coefficient of modal flexibility curvature was discussed and the proper number is given.

Sign in / Sign up

Export Citation Format

Share Document