Based on the efforts of individual companies and collaborative efforts through the ACC Club and the CFRRA, it would appear that the number of projects using composite elements in the form of internal reinforcement in the form of tendons/cables, or in the form of external reinforcement for purposes of retrofit, or rehabilitation, will increase. Companies are finding innovative niche applications for composites such as in NOMST and NEFMAC reinforcement for shield cuttable wall reinforcement, and the use of Technora aramid fiber based elements for connection of blocks for external post-tensioning. The premium placed on space, combined with the emphasis on rapid transportation, as well as on the dual precepts of "Creating New Technology that Responds to Society's Needs" for enhanced overall quality of life, are already pushing engineering and construction firms in Japan to develop and implement technologies that would enable the construction of entire "city-complexes" rising above existing cities, or underground or in the oceans. There is also a growing demand for bridges incorporating longer unsupported spans (Fig. 5.2) while combining form and function into elements that would blend unobtrusively into the surrounding environment. These and other concepts for faster and safer construction of buildings, enclosure-controlled environment amusement parks, and other structures provide immense opportunities for the use of fiber reinforced composites, both by themselves and in conjunction with conventional and emerging construction materials. Research is already underway at companies such as Shimizu, Sumitomo Construction, and Kajima Construction to use fiber reinforced composites in the drive to achieve these and other goals.
Figures 5.1-5.3 show examples of technologies and construction approaches for the future that are under study in Japan. The Shimizu Corp., in conjunction with other sectors such as the advanced materials sector, claims to already possess the technologies necessary to construct a "Super-High Rise" building of 800 m height that would straddle as many as 4 city blocks. One rendition of this concept (see Figs. B.33-B.34 in the Shumizu site report, Appendix B, p. 156) shows three super-blocks, one on top of the other. The company also is actively studying plans for the development of underground cities. Technologies being pursued include those related to construction methods, materials, artificial solar lighting systems and evaluation of physiological and psychological effects of such habitats.
Fig. 5.1. Sumitomo Construction Co., Ltd. is working on construction techniques for structures that are faster to build and of improved quality using precast elements applying both conventional and newly developed technologies and materials.
Fig. 5.2. Stress-ribbon bridges are thin, lightweight structures with high aesthetic appeal that may be a perfect application for lightweight, high strength, and high stiffness composite cables.
Fig. 5.3. A rendition of the three-dimensional "City in the Air" concept being studied by the Shimizu Corp. The megatruss construction serves as the basis for a pyramid 2000 m high that would house a million inhabitants in a biosphere of their own, yet would be contiguous with the atmosphere. The truss members themselves would house transportation facilities and other utilities.