Critical Bending Strain of Reinforcing Steel and the Buckled Bar Tension Test

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Title: Critical Bending Strain of Reinforcing Steel and the Buckled Bar Tension Test

Author(s): Leo Barcley and Mervyn Kowalsky

Publication: Materials Journal

Volume: 116

Issue: 3

Appears on pages(s): 53-61

Keywords: critical bending strain; fatigue; high-strength steel; reinforced concrete; reinforcing steel; seismic design

Date: 5/1/2019

Abstract:
The fracture of longitudinal reinforcing steel causes the loss of load-carrying capacity in reinforced concrete (RC) members. Results of large-scale reverse cyclic column tests have indicated that the fracture of longitudinal reinforcement is influenced by the amount of buckling experienced by the reinforcing steel. Similar behavior was observed in a material test as reinforcing bars fractured in a brittle manner when pulled in tension after buckling. Brittle fracture occurred after the bending strain from buckling exceeded the critical bending strain. A material test was developed to quantify the critical bending strain, called the buckled bar tension test. The rib radius of the reinforcing bar was found to influence the magnitude of the critical bending strain. Additionally, the results of column tests indicated that the critical bending strain of the longitudinal reinforcement affected the column displacement capacity. Finally, a relationship between axial displacement and strain from bending was developed.