Title:
Prepublished: Effect of High Axial Load on Cyclic Response of Exterior Beam-Column Joints with High-Strength Reinforcement
Author(s):
Hung-Jen Lee, Fu-Chi Yu, and Ker-Chun Lin
Publication:
Structural Journal
Volume:
Issue:
Appears on pages(s):
Keywords:
axial load; beam-column joint; confinement; joint shear; high-strength reinforcement; reversed cyclic loading.
DOI:
10.14359/51745667
Date:
3/6/2025
Abstract:
This paper investigates the seismic performance of exterior beam-column joints in special moment frames (SMFs) with varying axial load ratios. Cyclic testing of four additional specimens with an axial load ratio of 0.45 is compared with four companion specimens at 0.10. Each specimen was designed and constructed with Gr.60 (420), Gr.80 (550), or Gr. 100 (690) reinforcement in accordance with ACI CODE-318 provisions for special moment frame joints, except for the provisions of joint shear and confinement. While ACI CODE-318 tightens confinement requirements for SMF columns and joints, especially under high axial loads, this study reveals that increasing the axial load ratio benefits joint behavior. The study also demonstrates the feasibility of using high-strength reinforcement in exterior beam-column joints of SMFs, provided that appropriate modifications are made. The findings in this study have influenced modifications from ACI CODE-318 to the Building Code Requirements for Concrete Structures in Taiwan.