Developments in the seismic design of reinforced concrete frames in New Zealand

Abstract

A review of recent developments in the formulation of a design approach for ductile earthquake resisting reinforced concrete frames is presented. In particular the concepts of a deterministic design procedure, termed "capacity design," the advantages of moment redistribution, and the effects of gravity load dominance are discussed. In capacity design (a detailed definition of the term is given in Sect. 2.1) the designer attempts to enforce the development of a unique and desirable pattern of plastic hinges when these are required to dissipate significant amounts of energy to ensure the necessary hysteretic damping. The application of a capacity design procedure in determining the design actions for columns of multistorey frames is examined. Some issues relevant to instability during the inelastic dynamic response of frames are also discussed. Using recent experimental evidence, the inelastic behaviour of reinforced concrete columns, shear effects on potential plastic hinges, and special features of the behaviour of beam–column joints, when these are subjected to severe earthquake simulating reversed cyclic loading, are briefly described. Conclusions drawn from these recent experimental studies, which are being considered for incorporation into the new New Zealand concrete design code of practice, are also reported.