1st Croatian Conference on Earthquake Engineering 1CroCEE 2021

Wall Index (WI), also known as “wall density”, is a ratio of the total cross-sectional area for all structural walls aligned in one direction of the building’s floor plan and the gross floor plan area. Reconnaissance studies after past earthquakes in countries like Chile, Mexico, and China, confirmed that WI is one of the key parameters related to seismic performance of loadbearing masonry structures which influences the extent of earthquake damage. The WI requirements have been included in several international codes and guidelines. According to Eurocode 8 (EN 1998:1-2005), WI can be used as a design parameter for seismic design of simple masonry buildings with regular configuration and limited height up to 5 storeys, as an alternative to a more elaborate and complex seismic analyses approaches. The required WI for a building depends on the seismic hazard for the building site, number of storeys, type of masonry (unreinforced/reinforced/confined) and the mechanical properties of masonry (compressive/shear strength). WI can be also used for seismic assessment of existing masonry buildings in pre- and post-earthquake situations, as documented by studies from Chile and Mexico. The paper will provide a comparison of the masonry design requirements from selected codes, including the 1964 and 1981 Yugoslav technical regulations for design and construction of buildings in seismic regions and Eurocode 8. A case study of a masonry residential building which was damaged in the 2010 Kraljevo earthquake (M 5.5) and evaluated using different codes is also presented in the paper.