|Site:||Mitsubishi Chemical Training Center|
Tsukuba Creation Center (Main Entrance)
Ibaraki Prefecture, Japan
|Date Visited:||October 1996|
|Hosts:||Tokitaro Hoshijima, General Manager, Mitsubishi Chemical Corporation|
Tatsuo Ando, Manager, Carbon Fiber and Advanced Composites Materials Department, Mitsubishi Chemical Corporation
|Summary:||The front entrance of the center incorporates a 40.5 m long girder that was one of the first structures to use post-tensioned Leadline cables.|
The main entrance (Fig. B.82) consists of a post-tensioned concrete structure of length 40.5 m, width 0.3 m and height of 3 m that uses 4 sets of Leadline cables as shown in Figure B.83. The structure was built in October 1988 with a jacking and transfer stress of 65% of ultimate and a design load of 60% of ultimate. Each set of tendons consists of 8 rod like tendons using a wedge and sleeve type anchorage. Each rod is of 8 mm nominal diameter with a unit weight of 78 g/m and a guaranteed breaking strength of 11,300 kgf. The total length of carbon fiber reinforced rods used in this application was 1,360 m. The carbon fibers are unidirectional and pultruded into rods at 65% fiber volume fraction with an epoxy resin. Tensile strength is 2,550 MPa (nominal) Young's modulus is 147 GPa (nominal) with a 1.6% elongation and a relaxation ratio of 2-3% at 20ēC. The coefficient of thermal expansion is 0.7 x 10-6/ēC. Due to the lower weight of the cables, it is possible to pull them through the structural component without the use of heavy equipment (Fig. B.84) and the overall configuration can be stressed using conventional techniques (Fig. B.85).
Fig. B.82. Front view of entrance.
Fig. B.83. Close-up of the anchorage region showing cables.
Fig. B.84. Stretching and placement of cables.
Fig. B.85. Tensioning of cables using conventional equipment.