Damage Detection Method Based On Fractal Correlation Dimension For Steel Truss Structure

In recent years, steel structure is widely used in large industrial, civil and public buildings and facilities.With the use of prolonged time, overload and other problems, it makes the steel appeared more and more damage, failure, and other related issues. Therefore, the steel damage detection can not be ignored. Researchers are looking for more efficient and more accurate detection method. For steel’s unique structural forms, this paper studies the following aspects:2) This article describes the development of fractal theory, correlation dimension at home and abroad in recent years. Classification and comparison are carried out on the stage theoretical studies; Important parameter variables such as the concepts of phase space reconstruction, embedding dimension, time delay, scale-free zone are introduce in this paper. As an example structure of steel truss, it propose structural damage detection method based on correlation dimension of fractal theory and verify the possibility and applicability of the theory in structural damage detection.2) Using ANSYS software establish truss model in intact condition, single damage cases, and mutil-damage cases and make transient analysis of all nodes in different conditions.Acceleration response signal under different conditions are collected on each node. According to fractal theory,it processed the correlations dimension directly on the each node’s vibration signal in different structural damage conditions and fitted its the ln(r)-ln(Cr) graphics,then find the the relationship between the embedding dimension m and correlation dimension D.Finally, the absolute value △D of correlation dimension in the different conditions were analyzed and compared for determining the damage location of bars and discriminating degree of injury preliminary.3) Taking into account the impact of the external environment in actual testing process,this paper simulate the stability of theory under ambient noise circumstances.By random function,15% random noise applied into the acceleration signal of the truss node.Through correlation dimension analysis it reprocessed △ D value of the new node vibration signal which superimposed noise signal for determining of the method’s noise immunity and stability in structural damage detection under noisy environments.