Deformation Patterns and Behavior of Reinforced Concrete Walls with Low Aspect Ratios

The assessment of wall structures featuring low aspect ratios remains
a challenging problem due to their complex deformation patterns and susceptibility
to sudden shear failures under seismic actions. To address this issue, a
three-parameter kinematic theory (3PKT) for shear-dominated walls has been
recently proposed by Mihaylov et al. (2016). This rational approach uses only
three degrees of freedom to predict the complete load-displacement response of
a member, and captures shear failures occurring prior to or after the yielding of
longitudinal reinforcement. Due to its relative simplicity and computational
effectiveness, the 3PKT can be used for the performance-based evaluation of
existing structures. To further validate and extend the kinematic approach, an
experimental program was performed at the University of Liege, and is the focus
of this paper. The test campaign consisted of testing to failure of three cantilever
walls with an aspect ratio of 1.7, which featured uniformly distributed longitudinal
and transverse reinforcement. The main test variable was the level of
axial load which has a significant impact on the failure mechanism and lateral
displacement capacity. In addition to more conventional measurements using
displacement transducers, the experiments involved the measuring of the complete
deformation patterns of the walls using an optical LED system. This paper
presents the main test results in terms of load-displacement responses, crack
patterns and failure modes. The walls developed major diagonal cracks but
failed in flexure-dominated modes. The measured deformation patterns are
compared to the patterns predicted by the kinematic model for shear-dominated
walls. Even though the failure of the test specimens was governed by flexure,
their deformations were predicted well by the model.