Moment Connections Between Steel Beams and Concrete Columns

Mixed steel-concrete structural systems are common for the construction of high rise buildings. The efficiency of mixed systems can be substantially enhanced by developing moment connections between structural steel beams and reinforced concrete columns. Two methods for transferring the steel beam flange forces to the connection panel, level mechanisms and face bearing plates (FBP), were experimentally investigated. FBPs are steel plates welded to the beam at the column faces. Steel panel thickness, and the thickness, width and configuration of FBP were chosen as variables. Nine, 1/2 to 2/3 scale steel beam-concrete column subassemblages, representing interior connections, were tested under simulated monotonic lateral loads to examine the strength and stiffness of the connections.

The test results show that face bearing plates substantially enhanced joint strength. Variations in the thickness of these plates did not affect the joint capacity. The joint capacity, however, was increased by increasing the width of the FBP. Extending the FBPs above and below the beam was most effective and increased both the joint strength and stiffness.

Based on the test data, a design model which identifies principal forces on the connection panel was developed. The resistance to joint shear is furnished by a) steel panel in pure shear and b) concrete panel through diagonal compression strut. A design approach is proposed which can be used to detail the connections.