DESIGN DEMAND RECOMMENDATIONS FOR SELF-CENTERING ROCKING CORE WITH BUCKLING RESTRAINED COLUMNS

Abstract

Conventional lateral force resisting systems such as steel concentrically-braced frame (CBF) and steel moment resisting frames (MRFs) are designed for life safety performance during the design basis earthquake (DBE). The main properties of a CBF system are that it is economical and has considerable strength and stiffness. The system, however, has limited system ductility capacity prior to brace buckling. To remedy the systems shortcoming, A seismic resistant self-centering rocking core with buckling restrained columns (SC-RC-BRC) system, based on a self-centering CBF system, was developed by (Blebo & Roke, 2018) to withstand seismic lateral forces while limiting residual drift and structural damage. The system consists of steel members in a CBF configuration with buckling restrained columns (BRCs) at the first story level. The system can self-center due in part to post-tensioning (PT) bars located vertically along the external columns of the system. The system has suffers from under-predicting the design demand. This dissertation studies the effectiveness of the design demand procedure and two design demand approaches to improve design demand calculations. (1) load factor manipulation (Cline, 2021) and (2) Modified Modal Superposition (MMS) (Martin & Deierlein, 2021). This dissertation investigates multiple frames design demand, under multiple design procures. Overall results show an improvement in member design demand predictions, some members were overdesigned.