SEISMIC BEHAVIOUR OF METAL DUCT CONNECTIONS IN PRECAST CONCRETE PANELS

The seismic performance of grouted connections between precast concrete panels was questioned in New Zealand following the 2010/2011 Canterbury earthquakes. Inadequate connection detailing contributed to the failure of some panel connections, and recommendations for more robust detailing of grouted metal duct connections were published by the Structural Engineering Society of New Zealand. In the research reported here a set of experimental tests was conducted in order to evaluate the seismic behaviour of both previously used detailing and of currently-recommended detailing of precast concrete walls with grouted metal duct connections. A total of seven full-scale precast concrete walls were subjected to reverse cyclic in-plane lateral loading. The geometry and reinforcement detailing of the walls was based on a review of over 4800 constructed precast concrete panels in order to test realistic panel detailing. Various parameters such as the wall thickness, aspect ratio, axial load, number of layers of reinforcement, and the use of transverse reinforcement around the connections were included in the experimental programme. The tests confirmed that in-plane wall response was dominated by connection behaviour, with significant rocking at the wall-to-foundation interface. Failure was typically controlled by fracture of the vertical reinforcement at the connection. The existing connections performed adequately when subjected to in-plane cyclic loads, but performance was found to diminish as the axial load and the wall dimensions increased. The use of transverse confinement reinforcement around the grouted metal ducts was observed to improve the robustness of the reinforcement splice at large lateral drifts.