Moment redistribution in continuous beams of earthquake resistant multistorey reinforced concrete frames

Abstract

To allow a more uniform and efficient distribution of load resistance in reinforced concrete frames that may be subjected to seismic excitation well beyond the range of elastic response, the concepts of moment redistribution, well known from the plastic design of steel structures,
 are re-examined. The aims of moment redistribution, with particular reference to earthquake loading, are stated and relevant terms are defined. To allow advantageous but statically admissible adjustments of moments, derived from an elastic analysis, to be made, the requirements of equilibrium and lateral load resistance are assembled into a set of simple rules. Certain limits for redistribution, which appear to be reasonable
 in the light of existing provisions for structural ductility, and yet are not too restrictive, are proposed. A technique, involving simple graphic manipulations well suited for design office use, is suggested and with the aid of an example its application is shown in detail.