Title:
Performance of Mechanical Couplers in Hinge Regions of Concrete Walls with Grade 80 (550 MPa) Bars (Prepublished)
Author(s):
Narayan Budhathoki, Latip Kumar Sharma, Sudhir Niroula, Arjun Basnet, Wrya Abdullah, and Wassim M. Ghannoum
Publication:
Structural Journal
Volume:
Issue:
Appears on pages(s):
Keywords:
couplers; grade 80 (550 MPa); inelastic cyclic tests; low-cycle fatigue; mechanical splices; reinforcing bars; seismic performance
DOI:
10.14359/51751851
Date:
7/23/2026
Abstract:
The national concrete building code ACI CODE-318-19 permits the use of mechanical splices for Grade 60 (420 MPa) bars in hinge regions, but not for higher grade bars due to concerns over ductility and fatigue performance under reversed cyclic loading in the inelastic range of behavior. This study evaluates the seismic performance of mechanical splices with Grade 80 (550 MPa) ASTM A706 longitudinal bars through full-scale testing of four concrete walls detailed to satisfy ACI CODE-318-19 requirements for special structural walls. Walls were tested under constant compressive axial load and reversed cyclic displacements until loss of lateral strength and instability. Mechanical couplers were placed at the base of the cantilever walls. Coupler types and the manufacturing process of the coupled Grade 80 (550 MPa) longitudinal reinforcing bars were varied. The low-cycle fatigue performance of mechanical splices in the walls was compared with that of nominally identical mechanical splices tested under reversed inelastic cycles in air. Mechanical splices exhibited similar fatigue performance trends in both in-air and in-concrete tests. Findings support the development of a new seismic category for mechanical splices, incorporating strain-based pre-qualification using a reversed inelastic cyclic protocol representative of seismic demands in hinge regions.