Structural Crack Identification Based on the Variational Mode Decomposition

Abstract

In order to enrich the method of bridge damage detection and further improve the accuracy of bridge damage identification, a detection method of simply supported beam with crack under dynamic load is proposed, which is not based on the complete finite element model. Under the premise of not blocking traffic, the method only needs to analyze and deal with the acceleration response of simply supported beam span, which reduces the loading, unloading and maintenance of sensors in practical engineering. At the same time, based on the model, an analytical formula of acceleration in the mid-span of simply supported cracked beam is derived. Supported by theoretical derivation, instantaneous energy and mean energy difference are constructed by using variational mode decomposition and Hilbert transformation, which can effectively identify small cracks with 5% crack depth. Based on this, the influences of different wheel load, environmental noise and damage degree on detection results are studied. The results show that: ① The instantaneous frequency has a better recognition effect on crack location; ② The mean energy difference is sensitive to different crack depth ratio δ and wheel load; ③ This method has strong noise robustness.