Assessment of Historic Masonry by Cutting and Fracture Tests

Abstract

The existing stress and strain conditions of historic masonry structures are unknown due to several influences (e.g. damages, settlements, permanent loads). Their actual load carrying safety can only be assessed analytically by a conservative estimation of all imponderables. The result is often insufficient and may lead to a reduction of the allowed live load. By assessing experimentally the existing strain conditions using a slightly destructive method, the allowed live load may be increased. Thus some masonry structures can be prevented from demolition or be admitted to higher live load. The new developed method is based on the well known "Flat-Jack-Procedure" and shall improve the applications as well as the accuracy. It involves attaching measurement devices to the masonry surface, cutting longitudinally and horizontally and measuring the relief of strain. A mobile load device is used to collect information of the inhomogeneous specimen (consisting of brick and mortar). Thus Young's Modulus of Elasticity as well as the ultimate strain ε u are assessed. In this paper the theoretical background and the experimental set-up is described and examples show the achieved results.