During the past decade numerous researchers have investigated the dynamic behavior of structures with magnetorheological (MR) dampers using various semi-active control laws. A majority of the conclusions focused on the superiority of semi-active controllers over passive control. Large-scale MR dampers have not been studied extensively in conjunction with semi-active control laws since only a few experiments have been conducted with large-scale dampers. The assessment of semi-active controllers however needs to be verified more rigorously by using large-scale MR dampers. In this paper, real-time hybrid simulations using large-scale MR dampers are conducted to evaluate the effectiveness of various structural control strategies in enabling the seismic performance objectives of a building structure to be achieved. A prototype structure of a 3-story building is designed in accordance with the ICC code to satisfy the strength requirement, and an MR damper is installed to control the drift of the structure. Three diffe rent control strategies are considered: (1) passive control; (2) linear quadratic regulator (semi-active control); and (3) sliding mode control (semi-active control). Six ground motions scaled to the same design basis earthquake are used for the real-time hybrid simulations and statistical responses of the structure are obtained to compare the performance of each controller.