Retracted: A Novel Theoretical Model of Bite Force for Detecting Pre-Stress by Lift-Off Method

The lift-off method is an effective method to detect the effective pre-stress under the bridge anchor, but the mechanism of the force when the clip is disengaged is unclear. When using this method to detect pre-stress, how to determine the bite force of the clips to obtain the effective pre-stress under the anchor is not reported in the literature. Firstly, this paper analyzed the stress characteristics of the anchor system when the lift-off method is used, and analyzed the cause of the sudden change of the lift-off curve. Secondly, a theoretical method for calculating the bite force between the clips and the anchor plates was established, and the influence of the friction coefficient and tensile force on the bite force was analyzed. Thirdly, an indoor model test of clip bite force was designed, and the lift-off method outdoor test of an actual pre-stressed beam was carried out. The theoretical calculations and experimental values were compared and analyzed, and the results were in good agreement. On the basis of calculations and testing, we proposed a theoretical model of the linear relationship between the bite force and tensile force of the liftoff method, and recommended a formula for bite force based on test results. At the same time, based on theoretical calculations, we proposed a rational function fitting model for the friction coefficient and the linear slope of the bite force between the steel strand and the clips. The analysis shows that the friction coefficient of the proposed theoretical model is reasonable.