**2. Background**

A self-anchored suspension bridge with double towers and double cable planes (see Figure 3) was selected as the research object. The main span, side span, auxiliary span, cable sag ratio, and sag-span ratio of this bridge are 248 m, 108 m, 46 m, 49.6 m, and 1/5, respectively. The main tower is a double-tower portal structure system with a height of 80.5 m; the main cable is a parallel steel wire; the hanger is a parallel steel wire strand; and the stiffening girder is a steel–concrete composite girder system.

The construction of this self-anchored suspension bridge was initiated in 2011. A recent structural inspection revealed that the cable clamp close to the main tower has caused severe cable clamp slippage, as shown in Figure 4. Hence, this bridge was thoroughly checked for cable clamp slippage.

**Figure 3.** Overview of a self-anchored suspension bridge (m): (**a**) standard cross section at the hanger; (**b**) standard cross section without sling; (**c**) standard cross section of the main tower; (**d**) photo of a self-anchored suspension bridge.

**Figure 4.** Image and schematic of a cable clamp after slipping.

As showed in Figure 4, the sliding direction of the cable clamp is along the radial direction of the main cable. After inspection, the radial sliding distance of all cable clamps was measured in detail, and the number of each sliding cable clamp and the amount of slippage was recorded. In the establishment of the finite element model, adjusting the position of the cable clamp simulates the actual bridge stress condition. In order to emphasize the influence of the change in the position of the cable clamp on the whole bridge, the cable clamp with the largest slip amount is mainly simulated during the simulation.

During the inspection of the suspension bridge, it was found that the cable clamp that belonged to the third hanger in the mid-span direction of the W1 main tower was the most serious. A detailed inspection of the remaining cable clamps revealed that a total of 20 cable clamps in the whole bridge had slipped. Among them, there were 11 sliding positions of the west cable clamp, and 9 sliding positions of the east cable clamp. Figure 5 shows the downward positions of the cable clamps.

**Figure 5.** Positions of the cable clamps after slipping.

The measurements showed that five cable clamps slipped beyond 5 cm, and the maximum slippage was found to be 10.2 cm. Table 1 summarizes the slippage of the cable clip.


**Table 1.** Slippage of the cable clip.

Because of the slipping of several cable clamps, the variation in the structural force acting on the full bridge is complicated. To eliminate the numerous interferences and obtain the most representative situation, the slipping of a single cable clamp on one side is employed for the simulation. We established a model for the slipping of this clamp. In addition to considering the weight of the main cable, stiffening beams, main tower, and hangers, it is necessary to consider auxiliary components, such as the bridge deck paving, sidewalks, and guardrails, and convert them into constant loads for the simulation analysis. The dead load distribution of the bridge deck paving asphalt, sidewalks, and guardrails and other ancillary components is 132 kN/m.
