Damage quantification using spectral response of a multi-degree-of-freedom system with spatial and temporal stiffness variations: Application to shear-type frames

The present study is aiming to develop a spectral response-based closed-form expression of maximum damage intensity in a multi-degree-of-freedom system considering temporal and spatial variations of stiffness. The time-dependent variation of stiffness is incorporated in the formulation to simulate opening–closing mechanism of crack. In addition, an expression for multiple damage severity at consecutive stories is also derived. For the validation of the present method, numerical model of a shear-type frame is thoroughly investigated. It is observed from the analysis that incorporation of spectral amplitudes at modulated frequencies in the formulation, improves the assessment of damage severity. Further, an experiment on a scale-down 6-story steel building is performed for practical insights followed by two case studies with real data of a full-scale tower and an instrumented building. As the assumed temporal variation of stiffness is not generic, it may mislead the accuracy of estimated damage quantity in other incompatible scenarios.