PSI - Issue 44

Ernesto Grande et al. / Procedia Structural Integrity 44 (2023) 582–589 Grande et al. / Structural Integrity Procedia 00 (2022) 000–000

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modelling approach for the monotonic and cyclic behavior of exterior beam-column joints without transverse reinforcements, here the attention has been focused on the influence of the modelling approach of joints on the evaluation of the level of seismic vulnerability of RC-frames. Pushover analyses have been carried out with reference to an existing RC frame selected from the literature. The results deduced from the numerical analyses have underlined that, if the joint nonlinear behavior is neglected in the numerical modelling, the seismic capacity of the frame should be limited to the joint first cracking according to the current guidelines with the result of obtaining low values of seismic safety. On the contrary, the results derived from the structural model including explicitly the modelling of the beam-column joint allowed to consider the full shear deformation capacity of the frame, and leads to, for the analyzed case, a safety index similar to the one where the damage of the joint does not occur. The obtained results have allowed to identify the importance of a full exploitation of the beam-column joint deformation capacity, in place of restricting its limit performance at the first cracking condition in case of adopting a modelling strategy with rigid joints. The results clearly evidence the importance of including the effect of the beam column joints in structural models to properly investigate all the deformability contributions of existing RC buildings and to perform a realistic seismic vulnerability assessment. References De Risi, M. T., Ricci, P., Verderame, G. M., 2016. Modelling Exterior Unreinforced Beam-Column Joints in Seismic Analysis of Non-ductile RC Frames, in “ Earthquake Engineering and Structural Dynamics ”, 46 (6): 899–923. Del Vecchio, C., Di Ludovico, M., Prota, A., Manfredi, G., 2016. Modelling beam-column joints and FRP strengthening in the seismic performance assessment of RC existing frames, in “ Composite Structures ”, 142: 107-116. Grande, E., Imbimbo, M., Napoli, A., Nitiffi, R., Realfonzo, R. 2021a. A Macro Modelling Approach for RC Beam-Column Exterior Joints: First Results on Monotonic Behavior, in “ J. Building Engineering ”, 39: 1–16:102202 Grande, E., Imbimbo, M., Napoli, A., Nitiffi, R., Realfonzo R., 2021b. A Nonlinear Macro-Model for the Analysis of Monotonic and Cyclic Behaviour of Exterior RC Beam-Column Joints, in “ Frontiers in Materials ”, 8:719716. Hwang, S. and Lee, H., 1999. Analytical model for predicting shear strengths of exterior reinforced concrete beam-column joints for seismic resistance, in “ ACI Structural Journal ”, 96(5): 846-857. Jeon, J.S., Lowes, L.N., DesRoches, R., Brilakis, I., 2015. Fragility curves for non-ductile reinforced concrete frames that exhibit different component response mechanisms, in “ Engineering Structures ”, 85: 127-143. Kim, J. and LaFave, J. M., 2009. Joint Shear Behavior of Reinforced Concrete Beam-Column Connections Subjected to Seismic Lateral Loading, in “ Report No. NSEL-020 ”, University of Illinois at Urbana-Champaign. Lowes, L. N., and Altoontash, A, 2003. Modeling Reinforced-Concrete Beam-Column Joints Subjected to Cyclic Loading, in “ Journal of Structural Engineering .”, 129: 1686–1697. McKenna, F., Fenves, G.L., Scott, M.H., 2010. OpenSees: Open System for Earthquake Engineering Simulation, Berkeley, CA, USA: Pacific Earthquake Engineering Research Center. NTC 2018, Decreto Ministeriale 17 Gennaio 2018, Aggiornamento delle "Norme tecniche per le costruzioni". G.U. n.42 del 20 febbraio 2018. Sharma, A., Eligehausen, R., Reddy, G.R., 2011. A new model to simulate joint shear behavior of poorly detailed beam–column connections in RC structures under seismic loads, part I: exterior joints, in “ Engineering Structures ”, 33(3): 1034-1051. Shin, M. and LaFave, J. M., 2004. Modeling of Cyclic Joint Shear Deformation Contributions in RC Beam-Column Connections to Overall Frame Behavior, in “ Structural Engineering and Mechanics, ”, 18 (5): 645–669. Uzumeri, S.M., 1977. Strength and ductility of cast-in-place beam-column joints, American Concrete Institute Annual Convention, Symposium on Reinforced Concrete Structures in Seismic Zones, in “ ACI Symposium Publication ”, 53: 293-350.