Finite element modeling of masonry elements reinforced with the CAM system

Since most of the historical building heritage of many countries consists of masonry, such structures are of great interest in civil engineering. Unfortunately, the intrinsic chaotic nature of the masonry material results in poor tensile strength and poor ductility, from the mechanical point of view, and great modeling difficulties, from the engineering standpoint. Moreover, due to seismic events, human interventions and natural aging, masonry structures require the adoption of effective solutions aimed at the conservation, recovery, or preservation. Among the various techniques already available in the literature, this work focuses on the CAM® System. The CAM system is analyzed through a finite element macro-modeling approach, involving nonlinear constitutive laws. The proposed model is an enhancement of a formulation already available in the literature for unreinforced elements: masonry elements consider both plastic and damage effects and are based on a three-dimensional description of the stress–strain relationships, whereas the reinforcing tie ribbons (stainless-steel stripes) are discreetly modeled with truss elements, endowed with a tension-only bilinear constitutive law. In this computational framework, the main novelty regards the introduction of two new control parameters, able to sharply reduce the numerical instabilities revealed during some preliminary sensitivity studies. The outcomes given by the proposed model are also compared with the results gathered with experimental tests and other procedures: from the comparison, significant findings are collected from the perspective of structural modeling and design.