Relationship Between Damage and Dynamic Properties of a Short-Span Precast Concrete Slab

Abstract

This article presents a study on the relationship between damage levels and the dynamic properties of precast prestressed concrete slabs. The objective is to investigate the correlation between changes in natural frequency and damping ratio at various damage levels in the slabs. The findings aim to contribute to the development of an indirect structural health assessment approach based on dynamic property evaluation instead of traditional load testing. This method offers greater convenience, speed, and cost-efficiency. The study involved testing short-span precast concrete slabs with a thickness of 5 cm, a width of 35 cm, and reinforcement with four 4-mm PC wires. The span lengths of the slabs were 1, 1.5, and 2 meters, and they were subjected to point loads at mid-span to induce damage at different levels based on the ratio of deflection to load capacity. During the testing, the natural frequency and damping ratio of the slabs were measured. The results reveal that as slab damage increases, the natural frequency decreases, while the damping ratio increases. Notably, changes in the damping ratio were more sensitive to damage levels than changes in the natural frequency. Cracking in the slabs was observed when the natural frequency decreased by approximately 1–6%, while the damping ratio increased by about 10–20%. The proposed methodology can be extended to evaluate damage in slabs or beams of bridge structures using similar dynamic-based assessment techniques.