Double shear bolted bracket moment connections, part 1: Four-bolt configuration design methodology

Abstract

In this paper, a new rigid moment connection called Double Shear Bolted Brackets (DSBB) moment connection is introduced for use in Special Moment Frames (SMFs). The DSBB connection fastens each beam flange to column flange with three brackets including two internal brackets and one external bracket with pretensioned bolts. These brackets can be fabricated by casting or connecting bracket segments with welds. One of the main advantages of DSBB connection is the double shear performance of the connected bolts to the beam flange, and their less diameter of bolts compared to the other prequalified connections. Inherently, the less diameter of bolts in the DSBB connection reduces the bolt material usage and installation time of bolts. To develop the design method of the DSBB, first a precise analysis of the bracket thin-walled segments is conducted based on the yield line theory, then all applicable limit states of yield, rupture, and buckling failures subjected to corresponding actions are checked for the components of each bracket. In the following, the cyclic behavior of the connection introduced as a rigid moment connection is evaluated using high-fidelity finite element modeling. Then the study of energy dissipation is conducted on the connection's components and the beam and finally, the plastic hinge formation in the beam and the connection zone are controlled according to the plastic equivalent strain criterion. The results indicate that DSBB connection is acceptable as a fully restrained moment connection for application in SMFs and is an economical fast erection moment connection choice.