ABSTRACT
Steel moment frames have been widely used in earthquake sensitive regions due to their lightweight and ability to resist lateral forces induced by earthquakes. Although most seismic moment frames utilize wide flange beam to column connections, there has been recent interest in the development of square and rectangular tube-based moment frame systems to take advantage of the beneficial properties of closed sections, particularly low-rise systems. Previous studies showed the viability of tube-based moment connections, but the connection configurations can be improved by limiting the need for field welding. As a result, a tube-based collar connection concept is proposed and two collar connections are designed, fabricated and tested under cyclic loads. The findings from the two full scale cyclic tests provide important details on the hysteretic behavior, failure modes and sources of plastic rotation for these connections and suggest that they are able to meet current special moment frame requirements.
