In this paper, the technology of attractor phase space in chaotic theory is introduced and applied in the structural damage detection. Firstly the phase plane is constructed with the displacement and acceleration responses. Using the changes of phase plane topology of intact and damaged responses, a new damage index is extracted, and the structural damage existence and severity are identified successfully. Since some of the state variables can not be measured, a method of phase space reconstruction is proposed using single dynamic response. The dynamic responses are directly displayed into phase space, realizing transforming the signals from time domain to space domain. Then using the reconstructed phase space, the damage is diagnosed. The results indicate that the phase space reconstruction method has good robustness to noise, and higher sensitivity compared with traditional modal-based methods. The phase space reconstruction method can calculate the value of the damage index using single dynamic response, so that a single sensor can monitor structural damage existence and severity.

A new damage identification method for arch bridge structures under a moving load based on the difference of deflection is presented. The function of the deflection at the mid span of the arch with the changing positions of the moving load is derived using the Moore integral method. It can be concluded from the results that when the moving load is in the area without damage, this target indicates to be linear functions with the cosine of an angle (θ) between moving load and horizontal. Nevertheless, this target is multinomial with the change of cosθ in the damage area. In order to validate the proposed damage detection algorithm, a steel arch modal is simulated, which is proved to be practicable in projects. The results indicate that the location and degree of single damage can be identified accurately.

Intensive research efforts have been spent on vibration-based structural condition monitoring since structural vibration parameters are closely related to structural stiffness which can be used to identify, locate and quantify structural damage. This makes the vibration-based methods quite attractive for structural condition monitoring. This paper proposes to use strain mode for structural damage identification. A new index named Breach Threshold Value of Damage Levels (BTVDL) is proposed to quantify damage. To demonstrate the proposed method, responses of a circular arch with single and multiple damages are simulated using commercial software ANSYS. The simulated dynamic responses are used to identify the location and degree of the damage of the arch. The results demonstrate that strain mode is more sensitive to damages than others indexes such as frequencies and curvature modes. To further verify the method, a scaled arch model was fabricated and tested in the laboratory. Experimental results also confirm the high sensitivity and accuracy of using strain mode in structural damage identification. It is found that the simulated damages can be reliably identified by using the first two strain modes. The proposed method is more sensitive to damages and can be applied to monitoring structural conditions.