A multiscale experimental characterisation of Dutch unreinforced masonry buildings

In recent years, induced seismicity in the north of the Netherlands significantly increased. As a consequence, the seismic assessment of the built environment, which mainly consists of unreinforced masonry (URM) structures not designed for seismic loads, became of high relevance. Within this context, an extensive multiscale testing program has been performed at the laboratory of Delft University of Technology since 2014 to characterize the behavior of URM buildings from structural down to material level and provide benchmarks for the validation of numerical and analytical models. The paper presents an overview on the experimental campaign, which was structured in three phases: characterization of existing buildings; study of the structural response up to near collapse on replicated specimens; study of light damage state, also on replicated URM walls. The experimental campaign was characterized by a multiscale approach, with tests at structural, component, connection, and material level. At structural level, the campaign comprehended two quasi-static cyclic tests on full-scale two-story high assembled structures and a large number of both in-plane and out-of-plane tests performed either on single piers or on walls with openings. The in-plane stiffness and capacity of as-built and retrofitted timber floors was also assessed. At material level, destructive and slightly-destructive laboratory tests were performed on both existing and replicated masonry and timber specimens. Existing and retrofitting connections between the leaves of cavity walls and between concrete slabs and masonry veneers were studied. To study the initiation and propagation of cracking in URM structures, Digital Image Correlation (DIC) was used during dedicated in-plane tests.