Experimental and Numerical Investigation on the Seismic Response of Unreinforced Exterior Beam-Column Joints with Plain Bars

Worldwide, substandard Reinforced Concrete (RC) buildings with unreinforced beam-column joints are widespread also in seismic prone areas. This work presents the performed experimental campaign related to cyclic tests on exterior unreinforced joints. The main investigated parameters are: the joint aspect ratio, the design typology for the beam-column sub-assembly, the beam longitudinal reinforcement amount, and the longitudinal reinforcement typology. The effect of such parameters on the seismic response is first investigated experimentally. Then a modelling proposal for exterior unreinforced joints is described for exterior unreinforced joints with plain bars. The model is numerically efficient for extensive nonlinear analyses, based on experimental tests, easily implementable in common software platforms, and compatible with whatever modelling strategies adopted for the other RC members. The validation of such model is also performed through numerical-versus-experimental comparisons at the scale of the beam-column sub-assembly and at the scale of a whole frame.