Sponsors:  

Mountain-Plains Consortium (MPC) – University Transportation Center (UTC) 

Project Funds:  $285,146 ($142,509 from MPC and $142,637 match from SDSU)

Year:  2015-2018

Personnel:  

PI:  Mostafa Tazarv, PhD, PE

Co-PI:  Nadim Wehbe, PhD, PE

Graduate Research Assistant:  Puskar Kumar Dahal

Industry Collaborators/Donors:  Barsplice Products, Inc.,  Dayton Superior Corp.,  Dextra America, Inc.,  Erico International Corp.,  Epsilon Technology Corp.,  Headed Reinforcement Corp.,  and Splice Sleeve North America, Inc.

Project Summary:

Accelerated bridge construction (ABC) is a new paradigm in the USA mainly to expedite construction using new techniques, advanced planning, and novel detailing.  One method to connect precast columns to adjoining members is through the use of mechanical bar splices commonly referred to as couplers.  Even though current codes prohibit the application of couplers in the critical area of columns, recent studies have revealed the feasibility of precast columns utilizing couplers in the plastic hinge regions helping expanding ABC in high seismic zones.  The seismic performance is not a concern for none- or low-seismic states.  Nevertheless, the application of bar couplers in precast bridge columns located in these states is also scarce probably because of the uncertainty pertaining to the coupler performance, column connection performance, and an engineering precaution.  Utah, Florida, Colorado, and Washington have incorporated grouted sleeve bar couplers for bridge columns.  

There are several types of couplers in the market and new coupler types are emerging.  Their prime role is to shorten the splice length and to reduce bar congestion in connections.  Since bridge columns are the focus of the present study, couplers that transfer both tensile and compressive forces are investigated.  Five suitable coupler types for precast column connections are: shear screw couplers, (2) headed bar couplers, (3) grouted sleeve couplers, (4) threaded couplers, and (5) swaged couplers.  An extensive experimental program is undertaken to test all five types of mechanical bar splices available in the US market to obtain their properties and to generate a comprehensive database.  

Project Work Plan:

Task 1:  Prepare test matrix and test setup

Task 2:  Contact all the US mechanical bar coupler manufacturers to provide test samples

Task 3:  Develop a loading protocol and testing standard for couplers

Task 4:  Instrument all the samples then perform monotonic and cyclic tensile testing

Task 5:  Develop a comprehensive database for bar couplers

Task 6:  Develop a guideline including constructability, performance, and feasibility of each coupler type for ABC column construction

Task 7:  Prepare a final report including an executive summary, measured test data in the form of figures and tables, and recommendations.

Publications:

1. Dahal, P.K., and Tazarv, M. (2020). “Mechanical Bar Splices for Incorporation in Plastic Hinge Regions of RC Members,” Construction and Building Materials, Vol. 258, 120308, 17 pp. 

2. Dahal, P.K., Tazarv, M., and Wehbe, N. (2019). “Mechanical Bar Splices for Accelerated Construction of Bridge Columns,” North Dakota State University - Upper Great Plains Transportation Institute, Fargo: Mountain-Plains Consortium (MPC), MPC Report No. 19-372, 142 pp (Link). 

3. Dahal, P.K. "Mechanical Bar Splices for Accelerated Construction of Bridge Columns," MS Thesis, South Dakota State University, 155 pp., (Link).

Video of Monotonic Tests on No. 8 Couplers