Title: High-Strength Headed Bars in Joints of Special Moment Frames under Cyclic Loading

Author(s): Hung-Jen (Harry) Lee, Fu-Chi Yu, Ker-Chun Lin, Jui-Chen Wang, Benjamin L. Worsfold, and John F. Silva

Publication: Structural Journal

Volume:

Issue:

Appears on pages(s):

Keywords: anchorage; beam-column joint; development length; headed bars; joint shear; high-strength reinforcement; reversed cyclic loading

DOI: 10.14359/51740866

Date: 6/4/2024

Abstract:
This paper presents cyclic test results of nine beam-column joints, fabricated with Gr. 60 (420), 80 (550), and 100 (690) No. 11 (D36) headed bars in joints with matching concrete strengths. With the exception of the joint shear determination, each specimen was designed in accordance with ACI CODE-318-14 provisions for special moment frame joints. The headed bar embedment length was determined using 1.0f_y in accordance with the ACI CODE-318-14, rather than the ACI CODE-318-19 requirement to use 1.25f_y to calculate the development length. Test results demonstrate that ACI CODE-318-14 development length can be used for closely-spaced high-strength No. 11 (D36) headed bars in joints with code-conforming transverse reinforcement. This paper also aggregates the test data with prior research and compares the data with descriptive equations and breakout methodology for assessing the development length and anchorage strength of headed bars. The results support several design recommendations for the ACI CODE-318 provisions.