Seismic behaviour of different types of masonry spandrels

Most residential buildings that were constructed during the last century in Switzerland are 2-6 storey unreinforced masonry (URM) structures. At the beginning of the century, houses were constructed with timber floors and small bricks. This type of construction was later replaced by one which used larger, perforated bricks and reinforced concrete slabs. When assessing the seismic risk in Switzerland, a good understanding of the performance of the different types of URM buildings is mandatory. Numerical analyses have shown that spandrel beams have a significant influence on the seismic behaviour of URM structures since they influence strongly the stiffness and strength of the structure. However, until today, spandrel elements are often not considered when modelling URM structures because only very limited information on their force-deformation characteristics is available. For this reason a research project was initiated that aims at investigating the behaviour of different configurations of spandrel beams in URM walls using numerical and experimental methods. As part of the project large-scale, quasi-static monotonic and cyclic tests of spandrel beams were carried out. The test units represented spandrel beams in modern URM structures with reinforced concrete slabs or ring beams as well as spandrel beams in older URM structures with wooden floors. This paper presents the results of the test campaign on masonry spandrels in URM structures with wooden floors. Four spandrels were subjected to a quasi-static cyclic loading regime. The masonry spandrels were supported by either a timber lintel or a shallow masonry arch.