Model Updating Procedure to Enhance Structural Analysis in FE Code NOSA-ITACA

Abstract

This paper describes the model updating procedure implemented in NOSA-ITACA, a finite-element code for the structural analysis of masonry constructions of historical interest. The procedure, aimed at matching experimental frequencies and mode shapes, allows fine-tuning calculation of the free parameters in the model. The numerical method is briefly described, and some issues related to its Final Draft of the paper https://doi.org/10.1061/(ASCE)CF.1943-5509.0001303 2 robustness are addressed. The procedure is then applied to a simple case study and two historical structures in Tuscany, the Clock Tower in Lucca and the Maddalena bridge in Borgo a Mozzano.

Ambient Vibrations of Age-old Masonry Towers: Results of Long-term Dynamic Monitoring in the Historic Centre of Lucca

“…The instruments were moved along the tower's height by adopting three different layouts and combining data in order to identify four natural vibration frequencies and mode shapes of the tower, as described in . Data collected in this experiment also allowed evaluating the mechanical properties of the tower's constituent materials via model updating procedures, as described in (Girardi et al, 2019).…”

Nonlinear Fe Model Updating for Masonry Constructions via Linear Perturbation and Modal Analysis

“…The model updating algorithm allows for minimizing the discrepancy between the experimental and numerical frequencies, as the materials' constants vary within a given set. As in the case of linear elastic materials addressed in [18,19] the minimum problem to be solved is a nonlinear least squares problem. In the presence of masonry materials a further nonlinearity, due to the dependence of the tangent stiffness matrix on the solution to the equilibrium problem, affects the objective function and makes it impossible to resort to the efficient model reduction techniques adopted in [18,19].…”

“…with f the vector of the measured frequencies, f (x) the vector of numerical frequencies obtained from (1) and w i suitable weights. A numerical method for FE model updating of structures made of linear elastic materials has been described in [18,19]. The minimum problem addressed in [18,19] is a nonlinear least squares problem: the objective function, having the form (2), is nonlinear as the frequencies f (x) depend nonlinearly on the vector x of material properties.…”

“…A numerical method for FE model updating of structures made of linear elastic materials has been described in [18,19]. The minimum problem addressed in [18,19] is a nonlinear least squares problem: the objective function, having the form (2), is nonlinear as the frequencies f (x) depend nonlinearly on the vector x of material properties. In this paper, another source of nonlinearity of Φ(x) is the dependence of K T (x), and then of f (x), on the solution of the equilibrium problem in step (1).…”

Dynamic characterization of progressively damaged segmental masonry arches with one settled support: experimental and numerical analyses

“…10 shows the FE mesh generated by the code, where the individual masonry components, bricks and mortar joints, are highlighted in cyan and red, respectively, while the parts loaded with lime bags are displayed in yellow. A model updating [40] is performed on the FE model with the aim of estimating the Young's moduli E of the two masonry components (mortar and brick). The algorithm used and implemented in the NOSA-ITACA code for model updating is based on the construction of local parametric reduced order models embedded in a trust-region scheme.…”