16 th World Conference on Earthquake, 16WCEE 2017 Santiago Chile, January 9th to 13th 2017 Paper N° 3900 Registration Code: S-E1461887831 NUMERICAL INVESTIGATIONS ON RECTANGULAR SQUAT RENFORCED CONCRETE WALLS UNDER BI-DIRECTIONAL LOADING A. Niroomandi (1) , M. Soleymani Ashtiani (2) S. Pampanin (3) , R. P. Dhakal (4) , (1) PhD candidate, University of Canterbury, arsalan.niroomandi@pg.canterbury.ac.nz (2) PhD, Structural Engineer, Ian Connor Consulting Ltd., ms.ashtiani81@gmail.com (3) Professor, University of Canterbury, stefano.pampanin@canterbury.ac.nz (4) Professor, University of Canterbury, rajesh.dhakal@canterbury.ac.nz Abstract In recent earthquakes in Chile and New Zealand (2010 and 2011, respectively), reinforced concrete (RC) walls underwent failure mechanisms which were not observed/reported in previous earthquakes. Some of these failure modes included out-of-plane displacements, which could potentially result from bi-directional excitations. As a result, a global concern has risen on the contribution of bi-directional loading towards performance and failure mechanisms of RC walls. Nevertheless the effects of bi-directional loading on design/assessment of rectangular walls have not yet been scrutinized. Squat RC walls are widely used as lateral load resisting system in different structures. Few investigations are carried out on seismic behaviour of such walls. There is still a significant uncertainty regarding the behaviour of these walls under earthquake loading as well as their failure mechanisms, and strengths and deformation capacities. This paper presents results of a preliminary numerical investigation on the effect of bi-directional loading on rectangular squat RC walls. The numerical study is conducted using Finite Element (FE) analysis by DIANA. The FE model has been verified against experimental tests in another study. This preliminary parametric study is performed in order to identify the key parameters influencing seismic performance of rectangular squat RC walls under uni- and bi- directional loadings. Parameters such as confinement length, thickness, shear reinforcement and longitudinal reinforcement ratios are investigated in this study. The study also evaluates the effect of bi-directional loading on the stiffness, strength and drift capacity and failure modes of squat walls. More walls will be investigated for each parameter in a future study by the authors. Keywords: rectangular squat RC walls; numerical parametric study; bi-directional loading; crack width; failure mode