The hybrid test was composed of an experimentally tested isolated two story moment frame that represented a superstructure and a numerically simulated lumped mass substructure. A unidirectional shake table was constructed for the real time loading. The shake table, shown in Figure 1, consists of a large steel platform isolated on linear guide rails. The friction in the rails was specified as less than 10%. The steel platform is 5.8 m long by 2 m wide. The platform is supported at six points, directly below the locations of the frame columns. The shake table is driven by an MTS actuator with +/- 50 cm of stroke and 667 kN force capacity. The table is controlled using an MTS 493 Real-Time Controller. The digital controller provides closed-loop PID, differential Feedforward, and Delta-P control capabilities.