Numerical investigation in detection of prestress losses in prestressed concrete slab by modal analysis

Abstract

The paper presents a non-destructive method to detect prestress loss in prestressed hollow core slabs using a few modal frequencies. Loss of prestress is investigated by the 3D finite element model, using ANSYS software. A numerical model is used to estimate the percentage change in modal frequencies of prestressed slabs under various initial stresses induced in the tendon. Applicability and effectiveness of the proposed method are investigated by using various span lengths of slabs and elastic modulus of concrete. The parametric study shows that the minimal length of slab and maximal elastic modulus has the smallest influence on the percentage change in the modal frequencies. The results of this investigation thus indicate that proposed method can potentially be used to identify the initial stress reduction in concrete structures with minimal elastic modulus of concrete and the largest length of span.