Dynamic analysis of reinforced concrete frames including joint shear deformation

The rehabilitation of existing buildings requires an assessment of their la teral load resisting capacity which may be limited by the strength and duct ility capacity of their critical regions. From this assessment, a rehabilit ation strategy can be formulated. Lack of adequate confinement and shear re inforcement in the beam-column joints of existing reinforced concrete frame s may be the cause of brittle failure during a seismic event. Most of the n onlinear dynamic analysis programs assume infinitely rigid beam-column join ts in concrete frames regardless of the reinforcement detail. To properly a nalyze existing structures, a joint element is proposed and introduced in t he nonlinear dynamic analysis. The developed joint element accounts for ine lastic shear deformation and bar bond slip. The response of three- and nine -story existing frames with joint elements when subjected to dynamic loadin g was compared with the response of frames with rigid joint assumption and the response of rehabilitated frames. The results show that the modelling o f inelastic shear deformation in joints has a significant effect on the sei smic response in terms of drift and damage. The rigid joint assumption was found to be inappropriate when assessing the behaviour of existing nonducti le structures. (C) 1999 Elsevier Science Ltd. All rights reserved.