Bond slip model for generalized excitations

Correct evaluation for bond-slip effects is a crucial point when investigating progressive damage of reinforced concrete structures under random or earthquake excitations. For bridges, this aspect affects in particular the seismic response of piles' base and pier-deck joint in Integral Abutment Bridges as well. The need for a bond model, more accurate than those currently available in literature, without renouncing to ease of implementation, suggested to develop a new one. This model is defined by summing the effects of different bond resistance contributes (namely mechanical bond, friction bond and virgin bond) defined by means of continuous functions. This allows to fit, with reasonable precision, experimental monotonic and cyclic bond-slip paths, even along reloading branches. New relationships have been provided for updating the main law parameters at each load reversal. Moreover a specific progressive damage rule is introduced, able to account for generalized excitation. The proposed law has been validated by comparison with several existing pull-out cyclic data obtained from short-anchorage tests in good confinement conditions. © 2012 Taylor & Francis Group.