Studies on resistance behavior of modified blind-bolts under pure tension and shear

Abstract

Blind-bolts offer a feasible way for connecting a steel member with closed-hollow section to a member with open-section. However, the relatively higher cost of the available blind-bolts is an obstacle to practical application. For reducing the production cost, a modified Hollo-Bolt with standardized slotted sleeves (MBB) was proposed. To investigate the load-resisting behavior of the proposed MBB and conduct comparative studies with the normal blind-bolt (NBB), extensive experimental tests under pure tension and shear were performed on NBB and MBB of three different diameters and two common strength grades. The results indicate that MBBs and NBBs showed similar load-resisting behavior under tension as the fracture strength of the bolt shank solely controlled the ultimate tension-resisting capacity of the blind-bolt unit. Under simple shear, however, the load-resisting capacity of MBBs was slightly lower than that of NBBs due to the relatively shorter embedment length of its unslotted tube. Nonetheless, the load-resisting capacities of both MBBs and NBBs under simple shear were significantly higher than those of common high strength bolts, owing to contributions from the sleeve and unslotted tube. Moreover, finite element models incorporating ductile fracture criterion were established to replicate the load-resisting behavior of the blind-bolts under tested scenarios. It was revealed that the differences in the shear resistance of NBB and MBB were mainly attributable to the significant tensile stress of the bolt shank and the delayed damage of unslotted tube, which is essentially related to the embedment length of unslotted tube.