Evaluation of Column-Tree Moment Resisting Connection with End Plates and Haunched Beam (RESEARCH NOTE)

The column-tree constructional schemes allows for a reliable and convenient erection of moment resisting steel frames. Strengthening of column-tree connection with a haunch part can significantly improve seismic behavior of whole system. In the current study behavior of column-tree connections with haunched beams and end plate splices have been investigated. Special attention was paid for evaluation of the effect of haunch section length and presence of the beams bottom flange. Nonlinear finite element analysis has been used for numerical analyses. The results indicate an improvement of the load bearing capacity of specimens when a longer haunch was used and also when beam bottom flange existed in the haunch part. A direct relation between haunch length and the amount of stress in splice plates was also observed. However all connections showed ductile behavior during cyclic analysis, specimens with longer haunch revealed more desirable behavior. It was concluded that despite some deficiencies observed during the numerical tests, in presence of a longer haunch and also the beam's bottom flange, a noticeable improvement of the general behavior of connection can be achieved.