ANIDIS - L'ingegneria Sismica in Italia, ANIDIS XIX & ASSISi XVII - 2022

Dimensione del carattere:  Piccola  Media  Grande

Structural performance of unreinforced full-scale façade concrete beam-column joint

michele angiolilli, amedeo gregori, Roberto Tonelli, Claudio Tonelli

Ultima modifica: 2022-08-25


Post-earthquake observations have showed that poor reinforced concrete (RC) beam-column joints in existing structures determinates premature brittle failures during seismic action. Indeed, failure of these parts, which are crucial for transferring stresses and moments between beams and columns, resulted in the catastrophic collapse of structures in low to moderate seismic risk zones. Exterior (i.e. corner or façade) beam-column junctions of buildings constructed without or with insufficient transverse reinforcements are commonly involved in failure. The purpose of this study was to investigate the effective vulnerability of two full-scale exterior façade beam-column joints under transverse cyclic loading. The specimen design strategy and test setup were conceived to emphasize the vulnerability of the joints and, therefore, to achieve shear failure in the joint panel prior to yielding of both beam and column reinforcements under the simulated seismic action. In particular: (i) joints was characterized by the absence of any capacity design principle (i.e. total lack of stirrups in the joint panel) to highlight structural deficiencies typical of 1960s-70s Italian construction practice; (ii) beams and columns were adequately designed to remain in the elastic field during the tests; (iii) the specimens were evaluated in the absence of axial load. In this work, the experimental seismic performance is compared to the one predicted by code/literature models.

The test is then simulated using a numerical three-dimensional model for modeling crack propagation and fracture in concrete using the smeared crack technique. The model also allowed for a more comprehensive examination of the effects of certain assumptions on the mechanical performance of the RC joint during the test.

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