During the 1995 Hyogoken-Nanbu Earthquake, a large number of building structures sustained severe damage or even collapsed. The damage to steel buildings was also inevitable, particularly for old structures (ref.). Lessons learned from this and other recent earthquakes have critically motivated the structural engineering community toward the performance-based seismic design philosophy. Of various performance levels commonly considered, the provision against collapse is likely to be the most critical issue for building structures, considering high potential to cause a great loss of lives. In this regard, many strategies have been developed to improve the structural performance under a strong earthquake as well as to limit damage in the structure. This includes modifications of connection details and implementation of energy dissipaters. The latter is very promising especially for minimizing the structural damage. Due to the presence of energy dissipaters, the lateral stiffness and damping of the structure will be enhanced considerably. An improvement of the damped system to assure reliable seismic performance is a challenge topic awaiting for further development. As a new alternative for building constructions, an innovative damped weld-free steel framing system is proposed. This system is developed, in particular, to overcome uncertainties in the weld quality which were found to be a primary source of premature fracture of beam-to-column connections in moment-resisting frames (MRFs) damaged during the 1995 Hyogoken-Nanbu Earthquake (ref.). In the proposed system, high-strength bolts are mainly used instead of welds to connect beams and columns, and the conventional beam-to-column connection is replaced by a mechanical joint equipped with metallic-yielding damper. To verify the constructability and seismic performance of this system, a large experimental project entitled "Kyoto University Experimental Project of Steel Earthquake-Resistant Frames" has been launched at Kyoto University in collaboration with professional engineers from the industrial domain. The project is also aimed at reevaluating the seismic performance of improved MRFs (post-Kobe practice) and at characterizing the collapse margin of the MRFs. Two full-scale three-story steel building models will be tested using quasi-stactic and pseudo-dynamic loadings. Specimen 1 represents a conventional MRF constructed in accordance with post-Kobe practice. Specimen 2 is fabricated by using the developed mechanical joints and hysteretic dampers. Its superior performance over conventional MRFs is to be verified.