Site: Akashi Kaikyo Bridge
Honshu-Shikoku Bridge Authority
Hyogo Prefecture, Japan
Date Visited: October 1996
Hosts: M. Uemura, Tonen Corporation
Dr. U. Nishikawa, Head, Bridge Division, PWRI
Summary: The Akashi Kaikyo Bridge is designed to be the world's longest suspension bridge, once completed. A pilot rope consisting of dry aramid fiber was used in construction to facilitate the pulling and placement of heavier steel cables.

BACKGROUND

The Akashi Kaikyo Bridge will be the world's longest suspension bridge when completed in 1998. The main span alone equals 1,992 m with twin towers 283 m high. The bridge spans the Akashi straits from Honshu to Shikoku. The superstructure consists of a double deck stiffening steel truss carrying 6 lanes of highway traffic on the upper level and utilities on the lower deck.


Fig. B.44. A view of the bridge (October 1996, still under construction).


Fig. B.45. Dimensions and geometry of the Akashi-Kaikyo Bridge.

ACTIVITIES OF INTEREST

The pilot rope for the main cables consisted of dry aramid fibers within a protective polyethylene sheath (Fig. B.46). The light weight of the aramid pilot rope facilitated its easy placement by helicopter with a suspended cable drum (Fig. B.47). Once placed between the towers, it was used to pull the larger and heavier steel construction cables.


Fig. B.46. Sample of the aramid pilot rope.


Fig. B.47. Placement of the rope by helicopter.

The rope consisted of 800,000 strands of aramid. Table B.4 shows a comparison between the characteristics of the aramid rope and a conventional steel wire rope strand.

Table B.4

Material

Diameter (mm)

Rope Structure

Cross-sectional Area (mm2)

Weight/length (kg/m)

Tensile Strength (kN)

Polyaramid

10

1 mm sheath

8 mm bundle

25.9

0.0917

46

Steel Wire

Rope Strand

10

6 x 24 wire strands

34.8

0.332

49


Published: October 1998; WTEC Hyper-Librarian