Reinforcement of Masonry Structures

Abstract

A large part of all real estate properties is represented by masonry structures, which, in many cases, have a historical significance. The reinforcement, improvement, or seismic adjustment of such structures can often be carried out by using composite materials. Such reinforcement is obtained by applying to the masonry structural members a material characterized by a high tensile stress resistance, provided with a technologically compatible interface that, by ensuring adhesion to each single brick, can reduce shear stresses in the mortar interstitial beds, thus causing a single block-like behavior of the structure up to breaking.

Damages to masonry due to horizontal stresses, such as those caused by seismic events or slow ongoing settlements, are then attributed either to damaged mortar joints or to the breaking of masonry quoins. In particular, they are anticipated by the slipping of blocks towards the interface, after debonding.

The possible uses of composite materials available for the strengthening of structural members with a great number of technologies and geometries are numerous, and range from the use of fiber-reinforced polymer (FRP) or steel-reinforced polymer (SRP) sheets and fabrics, and the use of a mortar-based matrix system or also the lay-up of FRP-sized nets on masonry supports. For the reinforcement of masonry structures, the use of systems with matrices different from the epoxy matrices like the fiber-reinforced grout (FRG) or steel-reinforced grout (SRG) systems has gained more and more attention or, as an alternative to them, the use of systems consisting of FRP nets absorbed in specially prepared mortar matrices has been suggested.

The FRP reinforcement of masonry structures, along with improving the mechanical characteristics of the single structural members, allows for a large improvement in the structure undergoing seismic events and can be positively used in case they do not satisfy the safety requirements provided by the regulations in force concerning one or more limit states.

This chapter covers the techniques of reinforcement of masonry structures. It analyzes the method of calculating reinforcement systems and the most common applications.