Full-Scale Experimental Validation of a DAD Post-Tensioned Concrete Connection Utilising Embedded High Force-to-Volume Lead Dampers
An experimental validation of a jointed precast prestressed concrete connection, fitted with embedded high force-to-volume damping devices is presented. A full-scale beam-column subassembly based on Damage Avoidance Design (DAD) principles is experimentally examined to assess its seismic performance and damage avoidance capability. The test specimen is a 3D exterior connection of a jointed precast concrete frame structure, with prestress provided by unbounded post-tensioned high-alloy high-strength thread-bars.. Beam and column junctions in the joint region are armoured to avoid damage by providing steel plates at the interface surfaces. Supplemental energy dissipation is provided by high force-to-volume (HF2V) dampers internally cast into the beams adjacent to the beam-column interface. Multiple displacement histories are applied to investigate the contribution of the dampers to overall joint hysteresis and stability of the joint hysteretic performance. Tests are performed with and without the dampers connected, at a range of different post-tensioning forces, to delineate the effects of the different structural elements. Under uni-directional loading, the HF2V dampers provide significantly more damping than the post-tensioned DAD system alone. No strength degradation is observed over numerous tests and results are seen to be displacement path independent, whereby large initial cycles did not affect strength or stiffness on subsequent smaller cycles. The DAD concept is considered to be further validated based on the results of these tests.