The 1.70 m (5.6 ft) high socket foundations were posttensioned to the strong floor of the lab and overdesigned to minimize their interaction with the frame as the experimental program focused mainly on beam-column and panel-to-structure connections. In current building practice, the height of the socket foundations is commonly assumed to be greater than 1⁄10 of the total height of the structure, in accordance with basic considerations related to secondorder effects. To prevent any local undesirable mechanism from taking place in the socket foundations, the height was chosen to be approximately 1⁄5 of the total height of the structure and the reinforcement was overdesigned to ensure an elastic response. For the connection between the column and the socket foundation, the column embedment depth into the foundation was selected to be approximately 1.40 m (4.6 ft) (approximately three times larger than column depth). The base of the column was set into the socket foundation by means of a centering pin grouted into the 300 mm (12 in.) deep plate at the base of the socket foundation. High-strength mortar was injected to fill the 100 to 50 mm (4 to 2 in.) gap between the column and the socket foundation at top and bottom, respectively.