Fibre Reinforced Polymers (FRP) strips in series with Shape Memory Alloy (SMA) wires: theory, application and experimental results of a prototypal anti-seismic device in the framework of the MAMAS project

In the framework of the MAMAS Project (“Advanced Multi-task Materials for Structural Applications in Construction”), a scientific team (CETMA, ENEA, Ferrara and Florence Universities) realised a prototypal device made by CFRP (Carbon Fibre Reinforced Polymers) strips in series with SMA (Shape Memory Alloy) NiTi wires, devoted to strengthening masonry structures when quick prompt ringing is needed to face wall overturning in the post-earthquake emergency. In fact, the fibre delamination (i.e. decrease of stiffness and load bearing ability) should be avoided, because the repair effectiveness is not guaranteed if the accumulated effect of several seismic aftershocks leads to CFRP permanent damage and subsequent failure. Thanks to the intrinsic property of super-elasticity, the SMA device provides an undamaged CFRP behaviour during all the seismic sequence, with the additional advantage of re centring the wall subjected to out-of-plane actions. This paper describes the work from the CFRP+SMA device design to its final positive testing.