Damage assessment of modern masonry buildings after the L’Aquila earthquake

Abstract

This paper deals with the structural behaviour and the damage assessment of Italian “modern” masonry buildings during seismic events. “Modern” masonry buildings are characterized by a box-like structural behaviour, due to the presence of effective connections between horizontal floors and vertical load-bearing walls, which prevents local mechanisms such as the overturning of external facades during earthquakes. “Modern” masonry buildings were built in Italy since the first decades of XX century in those regions classified as seismic zone and since 1937 in the whole country, following the Italian code prescriptions that implicitly interdicted the erection of “ancient” masonry buildings. Starting from an in deep historical analysis of the Italian seismic codes’ prescriptions for the design of “modern” masonry buildings, the typical characteristics of the most frequent structural typologies of unreinforced masonry buildings are outlined. Then, the typical damage mechanisms observed in “modern” masonry buildings damaged after the L’Aquila earthquake (2009) are reported in relation with both the global and local behaviour of the whole building and its structural elements. The analysis demonstrated that “modern” masonry buildings experienced a good box-like seismic performance, which avoided global or local collapses, but shown severe damage to piers and spandrels related to their reduced in-plane shear capacity. Given the lack of data on such kind of structural typology, this study is fundamental for understanding and modelling the seismic behaviour of “modern” masonry buildings designed before ‘80s according to different seismic design prescriptions and for defining effective strengthening solutions for reducing their seismic vulnerability.