Impulsive Actions Due to Seismic Jerk and Design of Reinforcements to Counteract Their Effects in Masonry Buildings

Abstract

Studies on the impulsive content of seismic acceleration have highlighted the close correlation between damages caused by jerk and local failures with eventual trigger of chaotic collapses. The impulsive hammering actions can in fact generate stress concentration and consequently disaggregation. This study investigates the potential causes of structural node failures and identifies the interventions able to counteract the effects of jerk, particularly in the case of rubble stone masonry with low-quality mortar. Containment of masonry and placement of tensileresistant elements designed to absorb the impulsive stresses proved necessary. Placement of additional transversal elements constitutes a natural extension of reinforced plaster interventions, both with traditional and modern techniques such as FRCM. Through additional bentelements, the continuity of the reinforced plaster at the structural connections can be ensured. This aspect is often overlooked particularly in the connections between load-bearing walls and internal floor slabs. The interruption of reinforced plaster at the extrados and intrados of floor slabs constitutes, in fact, an important cause of local vulnerability.