Tensile resistance and design model of an external double-layered flange connection

Abstract

This paper puts forward a new type of flange connection to overcome the brittle fracture and lamellar tearing of traditional flange connections in long-span transmission towers. This new flange is called external double-layered (EDL) flange connection, which is usually applied to the connecting of circular hollow sections. Scale-down experiments and finite element analysis (FEA) were conducted to investigate the failure mode and bearing capacity of EDL flange connection under tensile load. Stress distributions and deformations of each component in the connection were measured and discussed. Parameter analysis was carried out to study some major influencing factors on the mechanical behaviours of the connection. Results manifested that the EDL flange connection had good ductility and failure mainly appeared in the upper flange plate. The flange plates were mainly subjected to compression in the thickness direction, so the lamellar tearing problem was avoided. The diameter of the bolts and the thickness of the upper plate had significant effects on the bearing capacities of the connection, while the thickness of the stiffened plates mainly affected the ductility. In the end, design methods of the flange plates, the stiffened plates, and the bolts were proposed based on the rigid plastic theory as well as the results of experiments and FEA.