On the Nonlinear Response of Masonry Arches Strengthened with BTRM

This paper introduces a straightforward nonlinear finite element modeling technique to gain insight into masonry arches reinforced with BTRM (Basalt Textile Reinforced Mortar), tailored for inexperienced users. Nonlinearities are concentrated on the reinforcement and on mortar joints, both represented by elastic perfectly brittle truss elements (cutoff bars). Bricks, on the other hand, are simulated using 4-node elastic elements. The objective is to assess the increase of the load-bearing capacity of BTRM-reinforced arches, while also bearing in mind the effect of anchor spikes. The strengthening system is meshed by elastic perfectly brittle cutoff bars directly linked to extrados nodes of the arch. These cutoff bars are tuned using standard coupon tests, considering the maximum possible tensile strength of the textile. Meanwhile, mortar joints are modeled with shear panels and cutoff bars - with elastic perfectly fragile behavior -, oriented perpendicular to the joint to assess their performance under pure Mode I failure. Essential parameters for defining mortar joints, including elastic modulus, Poisson's ratio, and tensile strength, can be readily obtained from standard experimental tests. The model's efficacy is verified through testing on a masonry arch reinforced with BTRM in a laboratory setting, validated by comparing numerical results with available experimental data. Through meticulous analysis of global force-displacement curves and assessment of nonlinearities within the numerical model, the simplicity and reliability of the presented method are evaluated.