Improving the seismic behaviour of reinforced concrete moment resisting frames by means of SMA bars and ultra-high performance concrete

Abstract

In the design of concrete buildings in seismic zones, ductility is normally used to reduce design efforts and as a form of energy dissipation. This implies structural damage to buildings in the form of interstorey drifts that need to be subsequently repaired or demolished.Twelve moment resisting frames (MRF) were designed with different geometrical configurations and new materials, and shape memory alloy bars and ultra-high performance concrete were used in the critical zones of the structure to improve their seismic behaviour. MRFs were subjected to a non-linear static pushover analysis and an incremental dynamic analysis to assess their behaviour. To do so, six real accelerograms were selected to study the response of the 12 MRFs, scaled at increasing peak ground acceleration (PGA). The base shear, the building’s overall plastic mechanism and the seismic response factors for the different geometrical and material combinations were analysed. The obtained values were compared with ASCE 7-05 and EC-8 proposals.It was concluded that the combination of shape memory alloys and ultra-high performance concrete allowed the behaviour factor to increase and residual drifts to decrease, which are advantages for both design and seismic behaviour.