Sensitivity analysis of frequency-based tie-rod axial load evaluation methods

Abstract

Abstract Tie-rods are often crucial elements for the safety of cultural heritage assets, having been employed both in new constructions and as a retrofitting intervention along the centuries. Several experimental techniques exist to estimate their axial load, with frequency-based ones being the most common. Axial load evaluation depends on several parameters, related to the geometry, mechanical properties and boundary conditions of tie-rods. In engineering practice, uncertainties affect the measurement of such parameters, and may compromise axial load evaluation. The present research focuses on a sensitivity analysis of the eigenfrequency computing model on which many dynamic tie-rod axial load estimation methods are based. Through the application of general Polynomial Chaos Expansion and the calculation of Sobol’ indices, the influence of relevant parameters on eigenfrequencies is investigated. The results, together with a real-life application on tie-rods of the historical buildings in Pisa (Italy), are then used to derive practical recommendations for practitioners and researchers in the field of cultural heritage preservation.