AUTHOR=Grande Ernesto , Imbimbo Maura , Napoli Annalisa , Nitiffi Riccardo , Realfonzo Roberto TITLE=A Nonlinear Macro-Model for the Analysis of Monotonic and Cyclic Behaviour of Exterior RC Beam-Column Joints JOURNAL=Frontiers in Materials VOLUME=8 YEAR=2021 URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2021.719716 DOI=10.3389/fmats.2021.719716 ISSN=2296-8016 ABSTRACT=
The study presents a numerical investigation on exterior reinforced concrete (RC) beam-column joints under seismic actions based on a macro-modelling approach proposed by the authors in a recent paper. The followed approach makes use of the well-known “scissors model” where two nonlinear rotational springs arranged in series were introduced to schematize the shear behavior of the joint panel and, moreover, the possible occurrence of the debonding of longitudinal steel rebars at the beam-joint interface. In this paper, the scissor model is employed in the context of a novel predictive approach with the twofold objective to: 1) develop a new model for the estimate of the maximum shear strength of RC joints by performing a multivariate linear regression analysis on a set of experimental tests and, 2) define a new multilinear backbone joint shear stress-strain law to be assigned to one of the mentioned springs. In particular, the identification of the shear strain parameters is obtained by performing a sensitivity analysis in which a number of monotonic load-drift numerical curves are derived by varying the strain values in ranges opportunely a-priori defined and compared with the experimental ones to investigate their accuracy. Finally, cyclic analyses on RC joints collected in the experimental database are carried out by considering the backbone joint shear stress-strain law identified in the calibration process. The analyses are performed by using the nonlinear open-source finite element platform, OpenSees, in which the “