Currently there are many use of threaded reinforcing
bars in construction fields because those do not need additional screw
processing when connecting reinforcing bar by threaded coupler. In
this study, reinforced concrete bridge piers using threaded rebar
coupler system at the plastic hinge area were tested to evaluate seismic
performance. The test results showed that threads of the threaded rebar
coupler system could be loosened while under tension-compression
cyclic loading because tolerance and rib face angle of a threaded rebar
coupler system are greater than that of a conventional ribbed rebar
coupler system. As a result, cracks were concentrated just outside of
the mechanical coupler and stiffness of reinforced concrete bridge pier
decreased. Therefore, it is recommended that connection ratio of
mechanical couplers in one section shall be below 50% in order that
cracks are not concentrated just outside of the mechanical coupler.
Also, reduced stiffness of the specimen should be considered when
using the threaded rebar coupler system.
 ACI Committee 318, “Building Code Requirements for Structural
Concrete (ACI 318-11) and Commentary,” American Concrete Institute,
Farmington Hills, MI, 2011, 503 pp.
 Korea Concrete Institute, “Code Requirements for Structural Concrete
(KCI-2012),” Korea Concrete Institute, Seoul, Korea, 2012, 342 pp. (In
 ASTM A706 / A706M-14, “Standard Specification for Deformed and
Plain Low-Alloy Steel Bars for Concrete Reinforcement,” ASTM
International, West Conshohocken, PA, 2014, 7 pp.
 Korea Standards Association, “KS D 0249:2003 - Method of Inspection
for Mechanical Splicing Joint of Bars for Concrete Reinforcement,”
Korea Standards Association, Seoul, Korea, 2003, 8 pp.
 Park, R., “Evaluation of Ductility of Structures and Structural
Assemblages from Laboratory Testing,” Bulletin of the New Zealand
National Society for Earthquake Engineering, vol. 23, no. 3, 1989, pp.