DESIGN OF EARTHQUAKE AND WIND RESISTANT STRUCTURAL SYSTEMS COMPOSED OF COMPOSITE AND CONVENTIONAL MATERIALS

Abstract

Many studies have proven the superior structural behavior of concrete-filled steel tubes (CFST) ' when compared to reinforced concrete or steel members. This can be explained while taking into account the stability due to concrete during the buckling of steel and confinement that the steel encasement offers to the concrete. The advantages of the concrete-filled steel tube column over other composite systems include: the steel tube provides formwork for the concrete, the concrete delays local buckling of the steel tube wall, the tube prohibits concrete spalling and adds significant stiffness to a frame compared to traditional steel frame construction. CFST columns combine the advantages of ductility, generally associated with steel structures, with the stiffness of a concrete structural system. In this dissertation, studies have been carried out for design of earthquake and wind resistant structural. systems composed of composite and conventional materials. Studies have been carried out on four types of eight storeyed building systems composed of different materials (i.e. structural steel building system, steel tube building system, R.C.C. building system and CFST-column-structural-steel-beam composite building system) and twenty storeyed building systems composed of R.C.C. and composite (CFST-column-structural-steel-beam) materials. In India, codal practice for CFST column design is not available whereas provisions for the same have been given by Architectural Institute of Japan (AIJ), Japan,which is based on elastic method of design. A methodology has been evolved enveloping the provisions of AIJ, Japan, IS: 800-1984 and IS: 456-2000 to have a conservative and safe design. Comparative study of different structural systems shows that CFST column building construction is costlier than R.C.C. building construction but cheaper than structural steel building construction. It is also found that the comparative cost of construction of CFST column building system with respect to R.C.C. building system remains almost constant with height of building.