Study on the bolting top-joint of substation truss–column

A new type of bolting top-joint of the substation truss–column was put forward and investigated in this paper. The top-joint is composed of one cover plate and two built-up tubes connected with high-strength bolts. The members of the bolting top-joint are much smaller than the common welding top-joint, the members are more convenient for fabrication, transportation and installation and the zinc process is much easier and cheaper. Firstly, as the dimensions and design loads of the welding truss–column in a 500 kV substation is concerned, the mechanic characteristics of 28 m long truss–columns including three bolting columns and one welding column were investigated numerically using finite element method. The results show that the mechanic characteristics of the proposed bolting truss–columns are comparative with those of the traditional welding truss–column. Then, the experimental model of bolting top-joint with 1:1 scale was built and the mechanic characteristics were studied experimentally. It was obtained from the numerical and experimental results that both the stiffness and the intensity of the proposed bolting top-joint depend on the thickness of the vertical plate as well as the number of bolt connections in the cover plate, and the bolting truss–column with this new kind of bolting top-joint could be used in substation structures instead of the common welding truss–column.