Providing life safety in major earthquakes has been the primary concern in current seismic design practice. However, maintaining the functionality of a building with minimal damage and negligible residual drifts after an earthquake event is the primary attribute for a resilient design. Beginning with the PREcast Seismic Structural Systems (PRESSS) program, several researchers have investigated the use of unbonded post-tensioned concrete walls to improve the earthquake performance of precast buildings beyond life safety. In this case, the post-tensioned strands are designed to remain elastic up to the design-level earthquake loading, thus providing a restoring force for the system. To ensure adequate amount of energy dissipation, additional damping elements are used that may undergo inelastic deformation to dissipate seismic energy imparted to the rocking wall. Precast Walls with End Columns, known as the PreWEC, is one such system. It uses a number of replaceable external energy dissipating steel connectors, namely O-connectors. Although these systems have produced satisfactory response when subjected to quasi-static lateral loading, their behavior has not been studied under dynamic loading. To address this concern, a large-scale shake table experimental program was undertaken as part of the NEES Rocking wall project to test four PreWEC systems using ground motions of different intensities. The main test variables included the amount of prestressing, numbers of connectors and base shear. This paper presents the experimental observations and preliminary results including global lateral responses, local responses and evidence for PreWEC to serve as a primary structural system in future resilient buildings.
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