ACTIVITIES OF INTEREST

The Kajima Corporation utilized Arapree (ARAmid PREstressing Element) reinforcing tendons for the top reinforcement of concrete slabs in the approach/exit sections of a parking structure that is equipped with sensors to monitor traffic flow (Fig. B.48). Previous use of conventional reinforcement in these areas had led to two detrimental effects: damage to sensor output through magnetic interference, and damage to sensors through application of concentrated vehicular loads in areas where conventional reinforcement was removed to prevent interference. Both effects are negated by the use of these nonmetallic reinforcing elements. The project used 470 m of flat Arapree elements.

Fig. B.48. Reinforcement details.

Fig. B.49. Arapree reinforcing bar.

Arapree elements consist of parallel aramid strands, impregnated with epoxy into flat bar stock. They have a regular knob pattern on the surface to promote bond and shear transfer (Fig. B.49). The material has properties as listed in Table B.5, and is fabricated by passing the fibers through eyelets and combs.

It is expected that the use of these elements will result in tremendous savings in the life-cycle costs of the sensor system since it will almost completely eliminate sensor replacement.