Influence of Structural Parameters on the Buckling of Longitudinal Steel Bar in RC Structural Wall

Reinforced Concrete (RC) structural wall is widely used in multistoried RC frame buildings to enhance lateral stiffness and lateral strength for earthquake resistance. One of the possible failure modes, observed during strong earthquake shaking, is the buckling of longitudinal steel reinforcement in the boundary elements of the wall. This also assumes importance in establishing damage states for seismic fragility analysis of RC wall. Although a few past studies have focussed on longitudinal bar buckling in RC members, detailed parametric study is absent particularly for such instability of bars in the boundary elements of the wall. In the present study, displacement-controlled nonlinear static analysis of several wall specimens is carried out using fibre-discretization of cross-section and distributed plasticity modelling in OpenSEES. Here, 27 different models of the isolated slender wall are created considering variations in six structural parameters, namely (a) length ratio of the boundary element to the wall, (b) axial force ratio, ratios of (c) longitudinal steel in web, and (d) transverse steel and (e) longitudinal steel in the boundary elements. The effect of wall thickness is accounted for through variation in axial force ratio. Using the analytical results from the nonlinear analysis of the wall models, the trends in drift ratio at the onset of longitudinal bar buckling damage states as functions of various key structural wall properties, has been investigated.