Review of the flat-jack method and lessons from extensive post-earthquake research campaign in Croatia

Abstract

Masonry structures are usually much vulnerable to seismic excitations and their behavior depends on numerous factors. The focus of this research is the determination of masonry mechanical properties by an on-site testing campaign. Commonly used methods and procedure proposals are briefly explained and then the flat-jack method is described in detail. The flat-jack method is based on stress transfer from a flat-jack to the masonry and it provides valuable information regarding vertical stresses, modulus of elasticity and shear strength of masonry walls. The main goal of this paper is to introduce the theoretical background and practical issues of the flat-jack method. The potential shortcomings, practical advice and several improvements of the method are presented. Conclusions are based on the extensive experimental campaign in post-earthquake assessments in Croatia. The flat-jack tests were performed on seventeen case study buildings and over thirty-five test locations.