This paper proposes an extension to RC interior beam-column joints of a model for the shear strength prediction
of exterior joints under seismic actions, already presented in the literature and based, for certain assumptions, on
a previous work of Park and Mosalam. The necessary changes, due to the joints\u2019 different physical configurations,
only one beam converging in exterior joints and two beams converging in interior ones, are introduced. In
the proposed model, on the basis of mechanical considerations, a direct formula for interior joint shear strength
accounting for the resisting contributions of three inclined concrete struts and of joint reinforcements, the
column horizontal stirrups and intermediate vertical bars, is derived. In comparison to the model for exterior
joints, three struts are considered instead of two and the influenced of the upper column axial load on the
inclination of the concrete struts is taken into account. The coefficients of the contributions of the struts and
reinforcements are calibrated using 69 test data sets available in the literature, selecting only cyclic tests
showing joint shear failure. For the validation of the proposed model, the shear strength predictions obtained
using the proposed expression are compared with those obtained from Kassem\u2019s model, Wang et al.\u2019s formula
and Kim and LaFave\u2019s formula, on a set of 28 specimens. It is also proposed a design formula, whose predictions
are compared to those of Eurocode 8 and ACI Code
