The present paper concerns the numerical study of the behavior of exterior RC beam–column joints under seismic actions by using a macro-modelling approach. The beam-column joint element is modelled through the well-known “scissors model” in which the two main mechanisms governing the overall behavior of the RC joints are considered by means of two nonlinear rotational springs in series. In particular, the first spring represents the shear deformation of the joint panel, while the second one represents the “fixed-end-rotation” of the beam due to the debonding of the longitudinal steel rebars at the beam-joint interface. In the model, the two springs are defined by proper moment-rotation constitutive laws selected from the literature. In particular, for the spring simulating the shear behavior of the joint panel, various combinations of some literature proposals are taken into account with the purpose to identify the laws better simulating the overall response of the RC joint. The numerical simulations are performed by using the OpenSees software in which the ability of the considered constitutive laws to reproduce the monotonic behavior of RC beam-column joints is assessed by considering an experimental database of cyclic tests collected from the literature. Finally, preliminary cyclic analyses are also carried out by considering the backbone envelopes of the best constitutive models previously identified in the calibration process. It is worth highlighting that, with respect to other similar literature approaches − often validated on the basis of a few experimental tests performed by the same proposals’ developers − the model presented herein is characterized by the following twofold advantage: a) easy to implement but, at the same time, capable of simulating both monotonic and cyclic response of tests with appreciable accuracy and, b) more robust and powerful since it was calibrated by considering experimental test results made available from a variety of researchers on the same typology of RC joints investigated.

A macro-modelling approach for RC beam-column exterior joints: First results on monotonic behaviour

Napoli, Annalisa;Realfonzo, Roberto
Membro del Collaboration Group
2021-01-01

Abstract

The present paper concerns the numerical study of the behavior of exterior RC beam–column joints under seismic actions by using a macro-modelling approach. The beam-column joint element is modelled through the well-known “scissors model” in which the two main mechanisms governing the overall behavior of the RC joints are considered by means of two nonlinear rotational springs in series. In particular, the first spring represents the shear deformation of the joint panel, while the second one represents the “fixed-end-rotation” of the beam due to the debonding of the longitudinal steel rebars at the beam-joint interface. In the model, the two springs are defined by proper moment-rotation constitutive laws selected from the literature. In particular, for the spring simulating the shear behavior of the joint panel, various combinations of some literature proposals are taken into account with the purpose to identify the laws better simulating the overall response of the RC joint. The numerical simulations are performed by using the OpenSees software in which the ability of the considered constitutive laws to reproduce the monotonic behavior of RC beam-column joints is assessed by considering an experimental database of cyclic tests collected from the literature. Finally, preliminary cyclic analyses are also carried out by considering the backbone envelopes of the best constitutive models previously identified in the calibration process. It is worth highlighting that, with respect to other similar literature approaches − often validated on the basis of a few experimental tests performed by the same proposals’ developers − the model presented herein is characterized by the following twofold advantage: a) easy to implement but, at the same time, capable of simulating both monotonic and cyclic response of tests with appreciable accuracy and, b) more robust and powerful since it was calibrated by considering experimental test results made available from a variety of researchers on the same typology of RC joints investigated.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11386/4758028
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