Quasi-static cyclic tests of two mixed reinforced concrete–unreinforced masonry wall structures

In several seismic countries, residential buildings are constructed using both reinforced concrete (RC) and unreinforced masonry (URM) walls. Despite their popularity, there is a general lack of knowledge concerning the seismic behaviour of such mixed systems and they are often designed using oversimplifying assumptions. For this reason, a research programme was initiated at EPFL with the objective of contributing to the understanding of the seismic behaviour of such structures. This paper presents two quasi-static cyclic tests on two-third scale models of a prototype structure. The two specimens are composed of a two-storey RC wall coupled to a two-storey URM wall by means of RC beams. The horizontal forces were applied at the two floor levels. The main difference between the two test units was the axial load applied at the top of the walls. A particular test set-up allowed measuring the reaction forces (axial force, shear force and bending moment) at the base of the URM wall. From the applied horizontal and vertical loads the reaction forces at the base of the RC wall were computed. It was hence possible to back-calculate the distribution of the reaction forces between the two walls. The article describes the design of the test units, the test set-up and the damage evolution during testing. The main results are summarised and behaviour patterns of mixed RC-URM wall structures identified.