Shear behaviour of old unreinforced masonry walls under seismic loading

Shear behaviour of old unreinforced masonry walls under seismic loading The determination of the safety of old masonry structures against earthquakes is a complex challenge. For instance it depends on the resistance of the structure, the seismic action and on many of uncertain structural details. Therefore the seismic impact itself and the behaviour of masonry under seismic loads is of high interest. The design of masonry structures, to resist earthquakes is normally a combination of experience and modern engineering knowledge, which is based on experimental research. Normally the design of a building is released in order to structural requirements and the seismic resistance which is verified by calculations according to valid standard, i.e. in Europe, Euro code 8 (EC 8). A lot of research and experimental work has been done in seismic behaviour of masonry structures in the last decades. Thereby new methods for seismic resistance evaluation and design, as well as new seismic resistant technologies and construction systems have been developed. Never the less these research studies and methods are mainly focused on new brick material. In case of new masonry structures the criteria against earthquake impacts, according to EC 8 standard, can be easily fulfilled. On the other side it is rather difficult to fulfill the EC 8 demands and reliability requirements for old masonry structures and heritage buildings without adequate strengthening. Laboratory tests on large unreinforced masonry walls have been performed to determine characteristic material parameters, like energy dissipation, stiffness, available resistance capacity and behaviour factor of old masonry. Based on these investigations a material model was calibrated for further numerical assessments. Finally the material model was used for the evaluation of the earthquake resistance of a typical residential masonry building. Thereby a finite element model was used. The objective of this paper is to present and discuss the experimental program as well as results of these tests and numerical application, using capacity spectrum-method.