Seismic Performance of 2D Regular Reinforced Concrete Frame Buildings Strengthened by Using Shape Memory Alloys

Reinforced concrete frame buildings are at risk of earthquake. Improving their response by adequate strengthening provision is an issue of major importance. Among the recent techniques introduced to increase the seismic resistance of this type of structure, shape memory alloy materials were found to be promising. They have large damping properties and significant re-centering capacity that reduce seismic efforts and limit damage. This work was dedicated to assessing the enhancement of building seismic capacity based on shape memory alloys of different sorts. Reinforcement consists of using rebars made from this material to replace longitudinal steel rebars in the critical zones of beams. A comparison of seismic performance induced by this technique with that associated with the conventional option relying entirely on steel as reinforcement was conducted. This was performed in the case of a medium-rise regular building subjected to medium and strong earthquakes when strengthened using four different shape memory materials including nickel titanium and ferrous-based alloys. SeismoStruct software was used to simulate the building through the static pushover analysis and the nonlinear time-history dynamic analysis. The building was anchored in the soil assumed to be rigid and the inelastic displacement-based beam element was used to discretize the structural members by setting up five integration sections and 150 fibers. In comparison with the steel-based option, it was found in both sites of construction that the use of shape memory yields an improvement in seismic resistance and re-centering performance. By using these smart reinforcements, the residual maximum inter-story displacement was reduced to less than a quarter of its value associated with the steel-based reinforcement. Furthermore, ferrous-based shape memory alloys were identified to yield a cost-effective strengthening alternative with regards to the common nickel titanium option and less than 10% of relative variation was observed in comparison with this latter.