Features of the carbon fiber strand rod

The CABKOMA Strand Rod for seismic reinforcement is a thermoplastic carbon fiber composite. It uses carbon fiber, which is an advanced material, as the interlining, while its outer layer is covered with synthetic fiber and inorganic fiber. It is finished by impregnation with thermoplastic resin.
  • 1.Its tensile strength is high, while it is the lightest seismic reinforcement in the world.
  • 2.Delicate but strong structural body
  • 3.Superb aesthetic quality that achieves lightness

Example of construction

Testing reinforcement with the CABKOMA Strand Rod Testing reinforcement with the CABKOMA Strand Rod

■Project for renovating the former head office building of Komatsu Seiren■Project for renovating the former head office building of Komatsu Seiren


The world’s first seismic reinforcement structure using a carbon fiber material designed by Kengo Kuma, a world-renowned architect
-- “fa-bo,” a fabric laboratory with a new building material proposed by a fiber company --

The former head office building of Komatsu Seiren was renovated with the world’s first seismic reinforcement that uses the CABKOMA Strand Rod, a thermoplastic carbon fiber composite, as the seismic reinforcing material. The use of textiles as building materials was also proposed -- including the “greenbiz” ultrafine porous spongy ceramic base, which is an eco-friendly building material. As a result, the building was recreated as the “fa-bo” fabric laboratory.

Go to the page showing the details of the “fa-bo” Komatsu
Seiren fabric laboratory.

Architectural designKengo Kuma and Associates

Structural designEjiri Structural Engineers

  • For the seismic reinforcement and renovation of the former head office building of Komatsu Seiren, a carbon fiber strand rod that was under development (hereafter, “CF rod”) was used, and a proposal was made in consideration of the possibility of a seismic reinforcing material with aesthetic quality.
  • Reinforcement with the CF rod is positioned as something that is over and above the requirement, and seismic reinforcement that satisfies the seismic performance required for conventional seismic reinforcement (Is = 0.60) has been done.

Comparison of mechanical strength

The photo shows a roll of CABKOMA Strand Rod.
Since a roll that is 160 meters long only weighs 12 kg, the material can be carried by hand.
Metal wire with the same degree of strength is about five times heavier.

Variety of coating materials and comparison of mechanical strength[CABKOMA: Strand of seven CF24K wires]

*For this project, 9 mm-diameter CABKOMA Strand Rod was used. The above values are measured values, not guaranteed values.

The photo on the left shows the CABKOMA Strand Rod compared with an iron wire. The strand rod and the iron wire shown in the photo are almost equal in terms of strength. Komatsu Seiren began developing CABKOMA in 2010. It was selected for the Ishikawa Jisedai Sangyou Souzou Fund Jigyou (Ishikawa Prefectural Government funds for creating next-generation industries). Since fiscal 2012, the development project has received the Sentan Gijutsu Jisshou Hyouka Setsubi-hi Tou Hojokin (subsidy for advanced technology demonstration and evaluation facility development, and others) from the Ministry of Economy, Trade and Industry.

Reinforcement effectConceptual rendering of reinforcement
  • Seismic reinforcement was achieved with exterior CF rod drape and interior partition brace bearing walls.
  • The structural investigation was aimed at investigating how to prevent the reinforcing materials from affecting the existing building as well as evaluating the seismic strength.
  • The target values of the reinforcement criteria are as follows: → Exterior CF rods: Around 3% / Partition brace bearing walls: Around 10%
Approach to reinforcement
The reinforcement was planned such that the target reinforcement values would be reached with the story drift (1/250) equivalent to Fu’=1.0 in the seismic reinforcement proposal for the building.

*1: At F=1.0 deformation, the target value (10% to 13%) is achieved through the reinforcement.
*2: At F=2.0 deformation, ls>0.60 is achieved in the shear strength of the wall if 20% shear force remains. (It is necessary to ensure that class 2 structural material is absent in the event of the above deformation.)

ExteriorCF rod drape
This is a proposal for seismic reinforcement based on the tension bracing effect of the CF rod. The reinforcing effect for the overall building can be obtained by linking the roof level and ground level (foundation level).

Verification of the reinforcement effect

InteriorPartition brace bearing wall
This is a proposal of a reinforcement method using tension brace comprising CF rods laid out in a diagonal mesh form. The reinforcing effect of the CF rods’ tensile resistance can be obtained by binding the surrounding steel frames to the existing building frame.

Verification of the reinforcement effect