Title: Effect of Aspect Ratio, Flanges, and Material Strength on Squat Reinforced Concrete Shear Walls

Author(s): Robert D. Devine, Steven M. Barbachyn, Ashley P. Thrall, and Yahya C. Kurama

Publication: Structural Journal

Volume: 117

Issue: 5

Appears on pages(s): 283-300

Keywords: flanged walls; high-strength concrete; high-strength steel reinforcement; low aspect ratio; nuclear structures; reinforced concrete; shear design; shear walls; squat walls

DOI: 10.14359/51725845

Date: 9/1/2020

Abstract:
This paper investigates the effect of moment-to-shear ratio and flanges on the behavior of squat reinforced concrete (RC) shear walls with high-strength materials. Pseudo-static, reversed-cyclic lateral load behavior of three squat walls—two rectangular walls with uniform thickness and different moment-to-shear ratios, and one I-shaped wall—are compared. The walls used high-strength reinforcement (fy ≈ 850 MPa [123 ksi]), high-strength concrete (fc' ≈ 100 MPa [14.5 ksi]), and the same uniformly distributed vertical and horizontal web reinforcement ratio, ρsw ≈ 0.83%. It is shown that: 1) squat rectangular walls without boundary regions can develop flexural failure, especially when using high-strength concrete; 2) the addition of flange regions at the wall ends increases shear-critical behaviors, such as increased shear deformations, steeper diagonal cracks, and crushing in the wall web; 3) web regions in flanged walls with high-strength concrete can have greater capacity than current ACI limits for normalized shear stress; and 4) current ACI (318-19 and 349-13) and ASCE/SEI (43-05) nominal lateral strength equations and relevant commentaries for squat walls may need to be updated to include the effects of moment-to-shear ratio, flanges, and high-strength materials.