Experimental and numerical study of precast posttensioned walls with yielding-based and friction-based energy dissipation

Abstract A precast posttensioned concrete wall system with supplemental yielding-based and friction-based energy dissipation is proposed, in which rectangular precast panels are stacked along horizontal joints, and unbonded posttensioning (PT) strands are placed inside ungrouted ducts to connect the panels to the foundation. Specially designed yielding-based and friction-based energy dissipation components are externally connected at the wall base using thru-bolts, thus allowing these components to be replaced after a large earthquake for the wall to regain most of its original lateral strength, stiffness, and energy-dissipating capacity. The proposed walls have a significantly expedited erection process by eliminating the casting and curing time of grout for splicing mild steel bars inside sleeves or corrugated metal ducts. The wall toes are protected by steel jackets from crushing as the walls rock along the horizontal panel-foundation joint at the base. Three wall specimens with varied initial prestress levels in PT strands, amounts of yielding-based and friction-based energy dissipation, and heights of the jacketed region, were experimentally investigated using quasi-static cyclic lateral loading. The test results demonstrated important features of the walls, including low damage and large self centering. The specimens were able to sustain drift levels (4%) much larger than the validation-level drift required by ACI ITG-5.1, with almost no reduction in lateral load from the overall peak applied load in each direction. Both the yielding-based and friction-based energy dissipation components worked as designed, and their combination significantly enhanced the energy dissipation capacity of the walls. A three-dimensional (3D) finite element model was also developed by comprehensively including all structural components and their interactions at the wall base. The model was able to capture not only the global hysteretic response of the walls, but also important local responses, such as concrete damage patterns, strain results, behaviors of yielding-based and friction-based energy dissipation components, and behaviors along the horizontal panel-foundation joints.