Retrofitting of Severely Damaged Concrete Piers using Ultra-High Performance Concrete

The use of Ultra-High Performance Concrete (UHPC) is gaining popularity for bridge applications in North America. UHPC has been used both in the construction of new and retrofitting of existing bridges. In this research, a novel use of UHPC as a concrete jacket for retrofitting of plastic hinge zones in cast-in-place and precast piers is proposed. Four large-scale cantilever pier specimens, two cast-in-place and two precast, are tested under cyclic quasi-static loading to drift ratios beyond Maximum Considered Earthquake (MCE). The piers are then retrofitted with UHPC jackets in their plastic hinge zones. The design philosophy for retrofitting is to shift the plastic hinge above the damaged region of a pier, thus re-instating capacity, stiffness, and ductility to the piers. Experimental results from testing of the piers along with guidelines on retrofitting and construction techniques are presented. It is shown that UHPC is indeed a competitive solution for retrofitting of concrete piers subjected to severe earthquake damage.