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Experimental assessment of the out-of-plane stability of ductile RC structural walls

Abstract:

Unexpected behaviors of rectangular reinforced concrete structural walls, reported during the 2010 Chile and 2011 New Zealand earthquakes, highlighted the significance of out-of-plane instability, which had been observed in laboratory tests many years prior. The local buckling mechanism of reinforced concrete structural walls (RCSW) was identified first in the 1980s. Phenomenological models were subsequently developed to relate in-plane tensile strains in the end region to the out-of-plane buckling deformations of the wall. The models comprise a respective out-of-plane curvature distribution along the potential plastic hinge region, mechanical properties of the materials, and geometry of the compression zone. Calibration of these models using prisms subjected to axial tensile and compressive cycles showed good promise in pbkp_redicting wall instability. However, these models did not consider the potential impact of different loading paths, for instance, the simultaneous occurrence of large tensile/compressive strains from in-plane loading and large interstory drift in the transverse out-of-plane direction on the buckling mechanism of RCSW. Prisms representative of the boundary elements of typical walls in Chile and New Zealand were built and tested in the Constructed Facility Laboratory at the NC State University. The experimental results showed that the onset of out-of-plane buckling instability of planar RCSW is mainly governed by the longitudinal steel content and the in-plane loading demands.