Type PR(partially restrained 'simple framing') is one of the methods of design specified in the AISC LRFD(1986) Design code for the design of unbraced steel building frames. In this method the connection restraint is ignored when resisting gravity loads, however, the same connections are assumed to be moment-resistant rigid connections when resisting loads due to earthquake or wind. This paper establishes the seismic performance of an eight story unbraced steel building frame designed based on Type PR design assumptions. Using realistic moment-rotation behavior for beam-to-column connections, the nonlinear dynamic responses of such frame subjected to a collection of earthquake records have been established. Floor lateral displacement envelopes and story shear envelopes have been presented.