Structural damage detection based on natural frequency vector

The fact that for a structure with certain extent of damage, the natural frequencies change accordingly compared to its primary intact structure, motivates to propose a novel concept of natural frequency vector. The natural frequency vector of the structure is simply formed by listing the natural frequencies as elements of the vector and for each damaged structure the natural frequency vector is unique. Following this, the natural frequency vector assurance criterion (NFVAC) is introduced and the principle of damage detection regarding NFVAC as damage index is described in details. An 8-stories shear frame is adopted as numerical simulation model to show the feasibility and validity of the proposed method. If the measuring noise, is neglected, the damage location and extent can be detected successfully when the damage exceeds the minimum detectable value which is simulated by a layer strut stiffness reduction. And when the random measuring noise of the natural frequencies is considered, the damage detecting results demonstrated that based on the concept of Damage Detection Probability, the structural damage can be successfully detected with high probability by NFVAC.