Cyclic Behavior of End-Plate Moment Connections

Three tests on large-size beam end-plate moment connections to column flanges under severe cyclic loading are reported. Such connections are used in the erection of low-rise Steel frames. Their use is advantageous where field welding is not advisable. In a conventionally designed end-plate connection, premature fracture of one of the inside bolts in a four-tension bolt type specimen occurs at a small number of cyclic load reversals. This clearly indicates unequal force distribution among the four-tension bolts. The end plate of this specimen is then reinforced with rib stiffeners in line with the webs, and stronger bolts are installed. This specimen shows excellent behavior under large cyclic loads. An additional specimen with larger bolts and a slightly thicker end plate also shows superior performance. It is evident that because of beam strain hardening, the required bolts must be larger than in a conventional design. Recommendations for increasing the strength of connecting bolts for four-tension bolt type of end-plate connections in seismic design conclude the paper.