Based on the extensive literature that has developed on structural health monitoring over the last 20 years, it can be argued that this field has matured to the point where several fundamental axioms, or gen eral principles, have emerged. The intention of this paper is to explicitly state and justify these axioms. In so doing, it is hoped that two subsequent goals are facilitated. First, the statement of such axioms will give new researchers in the field a starting point that alleviates the need to review the vast amounts of literature in this field. Second, the authors hope to stimulate discussion and thought within the community regarding these axioms.

The fundamental axioms of structural health monitoring

: This study investigated a number of different damage detection algorithms for structural health monitoring of a typical cable-stayed bridge. The Bayview Bridge, a cable-stayed bridge in Quincy, Illinois, was selected for the study. The focus was in comparing the viability of simplified techniques for practical applications. Accordingly, the numerical analysis involved development of a precise linear elastic finite element model (FEM) to simulate various structural health monitoring test scenarios with accelerometers. The Effective Independence Method was employed to locate the best distribution of the accelerometers along the length of the bridge. The simulated accelerometer data based on the FEM analysis was employed for the evaluation of the four damage identification methods investigated here. These methods included the Enhanced Coordinate Modal Assurance Criterion, Damage Index Method, Mode Shape Curvature Method, and Modal Flexibility Index Method. Some of these methods had been previously applied only to a number of specific bridges. However, the investigation here provides the relative merits and shortcomings of the damage detection methods in long-span cable-stayed bridges.

Numerical Evaluation of Vibration-Based Methods for Damage Assessment of Cable-Stayed Bridges

ii Acknowledgements iii List of Figures vii List of Tables x

Vibration Analysis of Cracked Composite Bending-torsion Beams for Damage Diagnosis

In this paper, a new approach based on the energy balance method is proposed for free vibration analysis of a cracked cantilever beam by taking into account both the structural damping and the damping due to the crack. Also, by taking into account the effect of opening and closing the crack during the beam vibration, the stiffness changes at the crack location are considered to be a nonlinear amplitude-dependent function which causes the frequencies and mode shapes of the beam to vary continuously with time. The results show that neglecting the effects of structural damping and nonlinear behavior of the crack will be a source of considerable error in obtaining the dynamic response and vibration characteristics of the cracked beam. In order to validate the results obtained through the proposed method, some experimental test have been conducted.

	 

	Key words: Damped vibration, nonlinear fatigue crack, structural damping, amplitude-dependent local stiffness, superharmonic, time-dependent mode shape.

https://academicjournals.org/article/article1380787970_Rezaee and Hassannejad.pdf

Damped free vibration analysis of a beam with a fatigue crack using energy balance method

Impact of time synchronization error on the mode-shape identification and damage detection/localization in WSNs for structural health monitoring

Over the past 25 years, the use of modal parameters for detecting damage has received considerable attention from the civil engineering community. The basic idea is that changes in the structure`s properties, primarily stiffness, will alter the dynamic properties of the structure such as frequencies and mode shapes, and properties derived from these quantities such as modal-based flexibility. In this paper, a method for nondestructive damage location in bridges, as determined by changes in the modal properties, is described. The damage detection algorithm is applied to pre- and post-damage modal properties measured on a bridge. Results of the analysis indicate that the method accurately locates the damage. Subjects relating to practical implementation of this damage identification algorithm that need further study are discussed.

Norris Stubbs

Papers

Field Verification of a Nondestructive Damage Location Algorithm