A Study on the Behavior of Beam to Boxed Column Connections with Peripheral Diaphragms

In this work, with the consideration of difficulties associated with the fabrication of boxed columns with internal continuity plates at the position of the beam to column connections, the behavior of connections with peripheral plates has been investigated with the aid of the finite element method. The following types of connections and suggested details have been studied: Model 1) beam to boxed column connection without any continuity plate, with direct welding to the column? Model 2) as above, with the column in-filled with concrete? Model 3) as the first model with added triangular horizontal plates to form a peripheral diaphragm in collaboration with the flanges of the beams? Model 4) same as the model 3 without welding at the juncture of the added plate to the corner of the column in order to reduce stress concentration? Model 5) same as the model 3 with the column in-filled with concrete? Model 6) same as the above with reduced weld at corners? Model 7) with the use of internal continuity plates? Model 8) same as the model 7 with the column in-filled with concrete? Model 9) same as the model 7 with beams of reduced flange sections (dog bone flanges), and Model 10) same as the model 3 with reduced flange sections (dog bone flanges). A comparison of the results indicates that the connections with the peripheral diaphragm plates, as suggested here, represent a desirable behavior/performance in terms of both strength and ductility. An increased ductility and reduced stress concentration may be achieved in the case of the use of the dog bone connections together with the peripheral triangular plates. In-¬filled concrete will also help to reduce the column plate deformations and increase the moment transfer capabilities of the beam to boxed column connections.