Using Nonlinear-Elastic Stiffness at Small Displacement to Identify Damage in a Full-Scale Reinforced Concrete Building

Abstract

In this paper, sensitivity of small-amplitude stiffness of a full-scale, three-story reinforced concrete flat-plate structure is investigated to assess development of damage during cyclic lateral load with up to 3.0% lateral drift ratio. The small-amplitude displacement tests were made at a maximum 0.03% drift ratio between the cycles of lateral loads causing mean roof drifts of 1.5% and 3.0% drift ratios. Results of the small-amplitude experimental program suggest that the building behaves as a nonlinear-elastic system at small displacement (i.e., drift ratio below 0.03%), and the small-amplitude stiffness compared at identical displacements can indicate damage from previous large-displacement cycles. It is shown that there is a robust and consistent relationship between stiffness and varying natural frequency measured at small displacements. As demonstrated, small-amplitude vibration properties may be an effective indicator of damage as long as a nonlinear-elastic model is used instead of a traditional linear model.