Two-stage damage identification method based on fractal theory and whale optimization algorithm

Abstract

Structural damage identification based on time domain method of vibration response has been widely developed in the recent decades, however, it still confronts some difficulties, such as measurement noise and model error. This paper proposes a novel two-stage damage identification method based on fractal dimension and whale optimization algorithm (WOA). In this study, based on vibration data, the difference in curvature of fractal dimension (DCFD) is used as the damage index to identify the location of suspicious damage elements in the first stage. A new objective function is proposed based on the curvature of fractal dimension (CFD) of acceleration signal, and the WOA is used to estimate the severity of the suspicious damaged element in the second stage. Firstly, the validity of the proposed method is verified by a numerical simply supported beam, and the results exhibit good damage identification ability. Then different noise levels (5% ~ 20%) are introduced into the dynamic responses to verify its robustness, the result shows that the method is of good anti-noise ability in the first stage. Although the second stage is slightly sensitive to noise, it can still effectively identify the severity of damage. Secondly, the vibration testing of a steel I-beam is designed to verify the rationality of the method in the application of actual structure. Finally, based on the simulated vibration test data of the I-40 Bridge, the applicability of the method to complex civil structure is verified, which shows that the method still has good ability to identify the location and severity of damage in complex structure and is of great significance in practical application.

The Current Development of Structural Health Monitoring for Bridges: A Review

“…The experimental results showed that the proposed method was effective without noise, but it was slightly sensitive to noise when quantifying the damage degree. Later, Huang et al [159] proposed a new objective function based on fractal dimension (FD) for WOA. In the simulation test, WOA could effectively identify the damage degree under noise conditions.…”

Temperature Effect on Vibration Properties and Vibration-Based Damage Identification of Bridge Structures: A Literature Review

“…Genetic Algorithm [59] The first one used in SDD Particle Swarm Optimization [60] Elite orientation for position updating Cuckoo Search [61,62] Random elimination mechanism Jaya Optimization [63,64] Parameter-free Moth-flame Optimization [65,66] Logarithmic spiral function for position updating Whale Optimization [67][68][69] Sunflower Optimization [70] Inverse square law radiation and random pollination Echolocation Search Algorithm [71] Dislocalization technique to avoid local optima Tug-of-war optimization [72] Originally proposed for SDI Gray Wolf optimization [73] Gray wolf hierarchy for the selection of the best agent Experience-based Learning (EBL) algorithm [74] Two modes to balance the exploration and exploitation Improved Optimization Tools PSO-CS [75] Better global search performance (PSO)-Simplex Algorithm [76,77] Improvement in the local search Enhanced MFO [78] Both global and local search abilities are enhanced Hybrid Jaya and Tree Seeds Algorithm [79] Avoiding local minimal Improved Jaya algorithm [80] Clustering strategy to enhance the global optimization capability Huang et al [59] introduced a genetic algorithm and an objective function constructed based on frequencies and mode shapes with different weight coefficients to address the issue of damage identification considering varying temperature effects. A three-span continuous beam and a two-span steel grid under temperature variation conditions were exploited to validate the method's feasibility.…”

Structural damage identification under ambient temperature variations based on CNN and normalized modal flexibility-autoregressive coefficients hybrid index

“…Structural damage identification (SDI), as an important part of structural health monitoring (SHM), aims to identify structural damage timely. During several decades, many methods have been proposed to solve this problem, one of the most popular is the vibration-based damage identification (VBDI) method (Guo et al, 2020; Huang et al, 2022). Although this kind of method has obtained good results, it still faces a challenge, namely, some external interference in the natural environment will cause fluctuations of measured dynamic characteristics.…”