THE SLIP CHARACTERISTICS AND PARAMETRIC STUDY OF BOLTED CONNECTIONS FOR TRANSMISSION TOWERS

Tension tests of twenty-one bolted joint samples in transmission towers were carried out. Finite element simulation analyses on some typical bolted joint samples were completed by ABAQUS software. Effect rules of some parameters on the load-deformation curves of bolted connections were analyzed. The main parameters include initial slippage, installation torque, roughness of contact surfaces, bolt-hole diameter and strength of the connected members. Based on the exponential model and the enhanced piecewise polynomial model respectively, nonlinear fitting analysis on the experimental load-deformation curves of bolted joints with one, two and three bolts at the fixed ends were carried out. The fitting parameters for two types of slippage models of bolted joints were determined, respectively. The feasibility of two slippage models of bolted joints for structural analysis of transmission towers was evaluated. The exponential model with clear physical meaning and large applicable range was proposed for structural analysis of transmission towers. For three cases of the maximum slippage, the idealized slippage and the minimum slippage, the fitting load-deformation curves based on the exponential model agree well with the experimental curves, and moreover, the slip process of the bolted connections can be accurately described by the exponential model. For the minimum slippage case, the difference between the fitting curve and the experimental curve in the linear increasing interval is relatively high, and the maximum is in the range between 10% and 20%.