New building systems based on a steel structure: A study of exterior wall cladding

Abstract

Recently, land costs in Japan have rocketed, and so the use of steel structures has greatly increased (Fig. 1). It happened because steel structures are well suited for multi-storey buildings, shortening construction time and labour, especially since concrete forms are not necessary. In 1988 steel structures exceeded 35% of total building construction (Fig. 2). This trend is especially impressive in small buildings and small mixed use housing/retail buildings in urban areas. Many of them consist of a steel frame, a cast-in-place concrete floor on a steel deck and exterior walls built of ALC (autoclaved light weight concrete). About 70% of the ALC produced in Japan is used for exterior walls (100 mm thick). Using the rough approximation that the ratio of exterior wall area to floor area is usually about the same from building to building, in.1988 10% of total building construction used ALC, which only four companies produce. Moreover, if one assumes that ALC is used only in steel structures, 30% of these buildings used ALC. Reasons for ALC’s popularity are as follows: (1) Simplicity as a building system. External perimeter walls are composed only of ALC, and dedicated parts for openings. (2) Supply system. ALC producers do not only manufacture, but also provide shop drawings according to the designer’s ideas, and also are concerned with the installation of these panels. ALC exterior walls are a kind of subsystem of the total system for the building (Fig. 3).