Title: Effect of Bend Radius of Reinforcing Bars on Knee Joints under Closing Moments

Author(s): Hwa-Ching Wang, Christopher S. Williams, and Gary J. Klein

Publication: Structural Journal

Volume: 117

Issue: 5

Appears on pages(s): 315-326

Keywords: bend radius; curved-bar node; frame corners; knee joints; strut-and- tie method

DOI: 10.14359/51725847

Date: 9/1/2020

Abstract:
An experimental program was conducted to investigate the behavior of reinforced concrete (RC) knee joints under closing moments. The geometry of knee joints creates a discontinuity region (D-region). Therefore, RC knee joints can be appropriately modeled and designed using the strut-and-tie method. At the outside of a knee joint under closing moments, a unique CTT node, known as a curved-bar node, develops. The evaluation of curved-bar nodes requires consideration of the bend radius of continuous longitudinal bars located along the outside of the joint. The experimental program described in this paper consisted of eight tests on knee joints under closing moments that were performed to study the effect of the bend radius of the longitudinal bars on the strength and behavior of the specimens and to evaluate a design equation for curved-bar nodes. An investigation into the effect of the mechanical reinforcement ratio of the longitudinal bars was also included.