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Earthquakes and Structures
  Volume 12, Number 1, January 2017 , pages 119-133
DOI: https://doi.org/10.12989/eas.2017.12.1.119
 


Modelling beam-to-column joints in seismic analysis of RC frames
Carmine Lima, Enzo Martinelli, Lorenzo Macorini and Bassam A. Izzuddin

 
Abstract
    Several theoretical and analytical formulations for the prediction of shear strength in reinforced concrete (RC) beam-to-column joints have been recently developed. Some of these predictive models are included in the most recent seismic codes and currently used in practical design. On the other hand, the influence of the stiffness and strength degradations in RC joints on the seismic performance of RC framed buildings has been only marginally studied, and it is generally neglected in practice-oriented seismic analysis. To investigate such influence, this paper proposes a numerical description for representing the cyclic response of RC exterior joints. This is then used in nonlinear numerical simulations of RC frames subjected to earthquake loading. According to the proposed strategy, RC joints are modelled using nonlinear rotational spring elements with strength and stiffness degradations and limited ductility under cyclic loading. The proposed joint model has been firstly calibrated against the results from experimental tests on 12 RC exterior joints. Subsequently, nonlinear static and dynamic analyses have been carried out on two-, three- and four-storey RC frames, which represent realistic existing structures designed according to old standards. The numerical results confirm that the global seismic response of the analysed RC frames is strongly affected by the hysteretic damage in the beam-to-column joints, which determines the failure mode of the frames. This highlights that neglecting the effects of joints damage may potentially lead to non-conservative seismic assessment of existing RC framed structures.
 
Key Words
    RC frames; joints; seismic analysis
 
Address
Carmine Lima, Enzo Martinelli: Department of Civil Engineering, University of Salerno, Via Giovanni Paolo II n. 132, 84084 Fisciano, Italy

Lorenzo Macorini and Bassam A. Izzuddin: Department of Civil and Environmental Engineering, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom
 

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