Limit analysis of CFRP reinforced masonry vaults: an appoximated incremental algorithm

A novel approximate methodology to approach the lower bound limit analysis [1] of masonry arch (and barrel vaults), reinforced by CFRP[2], is proposed. The masonry is no tension resistant with limitation of the compression strength. The model takes into account the shear failure, with sliding, along the mortar joints [3]. The shear resistance is the sum of the Mohr- Coulomb contribution of the mortar bed and the dowel-effect due to the CFRP reinforcement[4]. The basic idea on which the proposal methodology founds is to carry out a series of lower bound limit analysis. In each one the shear strength is constant and given by the Mohr-Coulomb friction law at the corresponding compression force, at each mortar joint, resulting from the previous step. In this way the associated flow rule holds at each step for the shear failure mechanism also without dilatancy. As well known the interface CFRPmasonry behavior is very far from being elastic-perfectly plastic but rather it’s strongly non linear with softening, as is typical for fracture cohesive mechanics, furthermore the iterative procedure presented is not rigorous. Therefore the results is to be considered only an approximation of the real load-bearing capacity of the masonry vaults reinforced by CFRP, especially under cyclic/seismic loads. Despite the necessary aforementioned consideration, the methodology results in very good agreement with available original experimental data’s from monotonic tests carried out by the authors on calcareous voussoirs masonry barrel vaults.