13th International Conference on Fracture June 16–21, 2013, Beijing, China -3- c F A σ= (1) in whichFis the cable force and cA being the effective cross section of each cable. Fig.2 Maximum and minimum loads in cables with/without traffic 2.2. Tightening and loosening of cables and wires Variations of the tension in the cable and wire, a set of a m σ σ for the cable and wire will be defined. They are referred to be Cases I and II. Case I 0 max max a η σ ησ σ = − ， 0 max max 2 m η ησ σ σ + = (2) Case II 0 max max a η σ σ ησ = − ， 0 max max 2 m ησ ησ σ + = (3) aσ and mσ respectively denote stress amplitude and mean stress. max ησ and 0 max σ in Eqs. (2) and (3) represent the maximum stress with and without traffic. Note the parameter α greater than 1 reflect the degree of cable tightening, while η less than 1 reflect the degree of cable loosening. Bear in mind that 1.0 η= stands for normal tension. Fig. 4 displays a plot of the product a m σ σ for the cables as a function of the cable position from left to right numbered as 1 to 52. The product 10 20 30 40 50 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 no.50 Cable force (KN) Numbering position of cables from left to right Max. force without traffic Max. force with traffic no.3 Fig.3 A typical section of the bridge cable
RkJQdWJsaXNoZXIy MjM0NDE=