Peak shear strength of squat reinforced concrete walls with boundary barbells or flanges

Squat reinforced concrete walls are important structural components of both conventional and safety-related nuclear structures because they may provide much or all of a structure's lateral strength and stiffness to resist earthquake and wind loadings. Equations are provided in the literature to compute the peak shear strength of squat walls. The utility of five such equations is evaluated using data from tests of 247 solid squat walls with barbell or flange boundary elements. Of the five equations studied, the use of the ASCE/SEI 43-05 equation resulted in a median ratio of predicted to measured strength slightly less than 1.0 with a relatively small coefficient of variation, although this equation does not include variables to account for the contribution of the barbells (flanges) to the peak strength. Importantly, the ASCE/SEI 43-05 equation underpredicts or overpredicts peak shear strength by a wide margin for many of the test specimens. Test data are also used to quantify the loss of maximum wall resistance with repeated cycling. The intercycle drop in strength and stiffness is significant, with the largest reductions observed for walls with aspect ratios less than 0.5.