Ductility and shear demands in reinforced concrete buildings with asymmetric walls

Abstract

This research aims to obtain envelopes of the ductility and shear demands in reinforced concrete (RC) wall buildings subjected to ground motions. These envelopes could be used in the future to provide design recommendations for RC wall buildings. A case study building with asymmetric walls (i.e. with non-rectangular cross sections) designed according to Eurocode 8 is analysed. In order to evaluate the seismic performance of the building, nonlinear response history analysis (NRHA) with increasing levels of ground motion intensity was performed. The asymmetric RC walls are modelled with two different approaches. The first model is characterised by concentrated inelasticity (MCI), since it considers the nonlinear behaviour only at the base of the walls. The second is a model with distributed inelasticity (MDI), which considers that the nonlinear behaviour can take place at any building level if the demand is larger than the wall yield capacity. In both modelling cases the nonlinear behaviour of the wall is represented using the tri-linear SINA hysteretic rule, calibrated with available experimental data. The computed distribution of the bending moments and shear forces along the wall height presents a significant discrepancy between MCI and MDI. However, the results obtained with the MDI are consistent with the provided moment strength. Finally, the curvature ductility demands at the base of the wall predicted by both models are similar. The main discrepancy between the two models is that ductility demands above the base of the walls are predicted by the MDI when the intensity of excitation increases.