The Analyses of Extended Shear Tab Steel Connections Part II: Stiffened Connections

The objective of this paper is similar to the companion paper published in the same issue of the Engineering Journal, to develop a viable, comprehensive 3-D finite element model capable of predicting the nonlinear behavior of shear tab connections, except this paper addresses in detail the analyses and failure prediction of the stiffened shear tab connection versus the unstiffened connections discussed in Part I. Correlation between the results of the computational finite element method and the experimental investigation is established and verified. Past experimental investigations have shown that the unstiffened shear tab connections are prone to twisting failure and low load-carrying capacity. Therefore, the use of stiffened shear tab connections is a viable design approach to overcome these problems. This paper compares various predicted failure modes from a finite element analysis with those observed in a recent experimental study performed by Sherman and Ghorbanpoor. In this paper, three, six, and eight-bolt stiffened extended shear tab connections are analyzed and compared. In addition, five FE models of 2-bolt and deep connections are analyzed in the plastic range to predict their failure modes. These models are two-bolt beam-to-column, 10-bolt beam-to-girder connection, 10-bolt beam-to-column connection, 12-bolt beam-to-girder connection, and 12-bolt beam-to-column connection.The three- and the five-bolt connections failed primarily in shear yielding, bearing failure of the holes around bolts, and in bolt shear. Secondary failure was observed in the form of girder web mechanism and shear tab twist. The eight-bolt connection failed primarily in bolt shear and bearing of holes around bolts. The failure modes predicted by the FE analysis were in agreement with those from the experimental investigation. The locations of high plastic strain, bearing failure of holes, plate twisting mechanism, and the web deterioration were identical in the FE model and the experimental observations. The FE model generated in this analysis proved to be accurate in predicting the failure mechanism of the extended shear tab connections.