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A wide range of reinforced concrete (RC) wall performance was observed following the 2010/2011 Canterbury earthquakes, with most walls performing as expected, but some exhibiting undesirable and unexpected damage and failure characteristics. A comprehensive research programme, funded by the Building Performance Branch of the New Zealand Ministry of Business, Innovation and Employment, and involving both numerical and experimental studies, was developed to investigate the unexpected damage observed in the earthquakes and provide recommendations for the design and assessment procedures for RC walls. In particular, the studies focused on the performance of lightly reinforced walls; precast walls and connections; ductile walls; walls subjected to bi-directional loading; and walls prone to out-of-plane instability. This paper summarises each research programme and provides practical recommendations for the design and assessment of RC walls based on key findings, including recommended changes to NZS 3101 and the NZ Seismic Assessment Guidelines.

The use of deformation capacity limits is becoming increasingly common in seismic design and assessment of reinforced concrete (RC) walls. Deformation capacity limits for RC walls in existing design and assessment documents are reviewed using a comprehensive database. It is found that the existing models are inconsistent and do not account for variation in deformation capacity with changes in the ratio of neutral axis depth to wall length ( c/ L w) and ratio of transverse reinforcement spacing to longitudinal bar diameter ( s/ d b) at the wall end region. A new mechanics-based model considering strain limits on the concrete and reinforcement is recommended. Concrete compressive strain limits for different levels of wall end region detailing are selected based on curvature ductilities for the walls in the database. Reinforcement tensile strain is limited based on a model for bar buckling. The proposed model, which accounts for c/ L w and s/ d b, is shown to have less dispersion and more accuracy than existing models when compared against experimental data and provides consistency between assessment and design provisions.

A number of finite element modeling approaches for reinforced concrete (RC) structural walls have recently become available for both research purposes and design applications. Five conceptually-different state-of-the-art finite element models for RC walls are described and evaluated in this paper, including models based on either a fixed-crack or a rotating-crack approach for simulating the biaxial behavior of concrete under plane-stress state, models characterized with either a single- or a multi-layered representation of the wall cross-section, and models with or without consideration of various individual failure mechanisms (e.g., buckling of reinforcement, out-of-plane instability). Modeling approaches were validated against experimental data obtained for five benchmark RC wall specimens, all with rectangular cross-sections, yet are differentiated by a range of salient response characteristics (e.g., aspect ratio, axial load, failure mechanism), in order to assess the capabilities of the models in representing the response of isolated planar walls under uni-directional lateral loading, as well as to identify future research directions. Results presented suggest that the models considered in this study can all capture the lateral load at yield and the peak lateral load capacity of the wall specimens with ±10% accuracy, while the initial stiffness and yield stiffness can be overestimated as much as 3.0 and 1.8 times, respectively. All models can capture nonlinear shear deformations and interaction between flexural and shear responses under cyclic loading, where the analytically-predicted flexural and shear deformations are within ±30% of the experimentally-measured values. Moderate differences between the predicted crack orientations and distributions are noted between the models, and the model results for the magnitudes of principal compressive stresses in concrete and the extent of stress localization are comparable. All models can capture the nonlinear distribution of vertical strains measured along the base of the walls, where the magnitudes of the predicted tensile and compressive strains are within ±50% of experimentally-measured strains for most models. Although some of the model formulations proved to be successful in capturing the experimentally-observed strength loss mechanisms for individual wall specimens, none of the models were capable of comprehensively simulating all of the strength degradation mechanisms observed during the tests.

Experimental testing was conducted on four large-scale, flexure-yielding walls with rectangular cross sections to investigate the impact of imposed axial load ratio (10, 14, and 20% of axia...