| Pier walls are occasionally used by Alaska DOT because of their in-plane lateral rigidity. The height-to-thickness ratios found in building applications can also be found in piers walls, increasing the possibility of buckling instability. Unexpected nonlinear behavior in planar reinforced concrete structural walls, reported during the 2010 Chile and 2011 New Zealand earthquakes, highlighted the significance of out-of-plane stability, which had been observed in laboratory tests many years prior. The local buckling mechanism of reinforced concrete structural walls (RCSW) was defined first in the 1980s. In-plane lateral loading causes large inelastic tensile strains in one of the boundary elements, accompanied by cracking at the level of the plastic hinge region. Under load reversals, out-of-plane deformations can be generated in the compression zone as a result of residual crack widths and eccentricity in the compression force at the wall toes. If the lateral deformation is sufficient, instability can occur followed by the loss of lateral and vertical load carrying capacity of the wall.;Analytical models created in the 1990s correlate in-plane tensile strains to out-of-plane buckling wall deformations resulting in instability. The models comprise a respective curvature distribution along the plastic hinge region, mechanical properties of the materials, and geometry of the compression zone. Past studies on prisms subjected to axial tensile and compressive cycles have demonstrated how promising the existing models are. However, these models do not consider the potential impact of different loading paths on the buckling mechanism of RCSW, suggesting further investigation.;Prisms representative of the boundary elements of prototype typical pier walls from Alaska DOT and structural walls from Chile and New Zealand were built and physical tests were conducted in the Constructed Facility Laboratory at the North Carolina State University. The aim of the tests was to evaluate the effect of different longitudinal reinforcement ratios in combination with different load paths on the onset of out-of-plane instability of planar special RCSW. Subsequently, a fiber-based computational model was developed and calibrated based on the response of the tested specimens. Later, a parametric study was conducted, where formerly identified critical parameters were considered in order to establish an out-of-plane buckling stability limit state as a function of longitudinal tensile strains reached at the end regions of RCSW.;The principal outcomes of the experimental program and the details of the fiber-based computational model are discussed in this report, along with the results of the parametric study, which indicated that imposed out-of-plane displacements do not impact stability. However, inplane loading history and longitudinal reinforcement ratio do impact the onset of the local buckling limit state. Finally, a new approach is proposed to prevent buckling instability of RCSW based on previous models, which confirmed to be less conservative for design purposes. |
