Experimental and Numerical Study on Rolling Friction in Tower Saddle of Suspension Bridges

Rolling friction pairs in the tower saddle of suspension bridges could significantly reduce the horizontal load that is transferred to the tower. To investigate the dependence of the rolling friction coefficient (mu) of a rolling friction pair on the normal load (fn) and the cylinder radius (R), an experiment was conducted where a sandwich-like mechanism measured mu. Based on the mu-fn-R relationship, a numerical model, which used one-dimensional (1D) Gaussian random nonplanar surface representation, was proposed in this research to calculate the overall rolling friction coefficient (mu T) of a multiroller plate system. The experimental results showed that the dependence of mu on fn and R could be divided into three stages: (1) roughness; (2) elastic; and (3) inelastic. In addition, mu was proportional to fn/R in the elastic stage. The proposed numerical model could accurately calculate mu T for a multiroller plate system. The mu T rose with increasing surface nonplanarity and slightly increased with the number of rollers (N). This clarified that the mu-fn-R relationship and proposed numerical model could help to quickly determine the size of the rollers and the flatness of plates during design and reduce the scale of the experiments required.