Cyclic out-of-plane behaviour of tall reinforced masonry walls under P-Δ effects

On the basis of experimental and numerical results, this paper discusses the out-of-plane behaviour of tall load-bearing reinforced masonry walls in a large-displacement regime, under the influence of vertical loads (P-Δ effects). Reinforced masonry systems can be advantageous for erecting one-storey commercial and industrial buildings 6-8 m high. These structures are often provided with deformable roofs and, as a consequence, in case of seismic actions out-of-plane forces can be significant in the wall behaviour and can lead to the onset of second order effects. For this structural configuration, a special set-up for out-of-plane cyclic tests was designed and built, to assess experimentally two reinforced masonry systems, gather information on their structural behaviour, and calibrate moment-curvature relationships to be implemented in numerical models. These models allowed the test results to be extended to different dead loads, degrees of wall slenderness, and quantities of reinforcement. The research validated the effectiveness of such systems and identified some limitations and procedures for modelling and design.