Seismic response of precast bridge columns with composite non-proprietary UHPC filled ducts ABC connections

Accelerated bridge construction (ABC) utilizes advanced planning, new construction techniques and innovative detailing to expedite construction of new bridges or rehabilitation and replacement of old deteriorated bridges. ABC has been widely used in low seismic regions and mostly implemented in the superstructure elements but much less considered for substructure elements such as column-base connections, especially in moderate and high seismic regions. While robust seismic ABC connections have been developed using ultra-high performance concrete (UHPC), sole sourcing of robust commercial UHPC mixes is causing bidding issues and limiting the wide adoption of such seismic ABC connections. Thus, validating alternative solutions that use non-proprietary materials could help overcome such challenges. This paper presents experimental and analytical investigation of the structural and seismic behavior of precast bridge columns with non-proprietary UHPC-filled ducts column-to-footing connections. For this study, a recently developed non-proprietary UHPC mix at the University of Nevada, Reno (UNR) is used. Two large-scale column models, varied only in reinforcement debonding, were tested at UNR under combined axial and cyclic lateral loading to evaluate their seismic performance. The column models were compared with reference cast-in-place column models and another column model incorporating proprietary commercial UHPC-filled duct connection from previous studies. The test results showed that the column models were emulative of conventional connections. Analytical modeling for the two tested columns was also conducted and shown to successfully reproduce the local and global behaviors of column models with acceptable accuracy when bond-slip and bar debonding effects are properly considered.