STR-992: DAMAGE DETECTION OF UHP-FRC PLATES USING RANDOM DECREMENT TECHNIQUE

This paper is about structural health monitoring using Random Decrement (RD) technique for Ultra High Performance Fiber Reinforced Concrete (UHP-FRC) slabs. Five simply supported slabs with identical dimensions are tested using low-velocity impact technique. Multi-impact load is applied at the mid-point of the UHP-FRC slabs by dropping a 475 kg steel weight from a constant height of 4.15 m. Two parameters are considered: namely: the steel reinforcement ratio, and the steel fiber volume content. The natural frequencies (eigenvalues) and corresponding mode shapes (eigenvectors) of tested plates are extracted numerically using linear perturbation analysis available in ABAQUS (Lanczos solver) to verify the experimental values extracted using RD signatures. The dynamic behavior (natural damped frequencies and damping ratio) of intact slabs and after applying the impact load is determined. The random decrement signatures are extracted and compared at intact and damage state. RD technique is used successfully to extract the dynamic characteristics of tested slabs with reasonable accuracy. Changes in dynamic parameters identify the existence and intensity of damage. As additional results, it is observed that steel fibers enhance the vibration behavior of slabs and the mobilization of reinforcements cause a noticeable change in natural frequency