ABSTRACT
In this paper, the issues regarding shear-moment interaction in plastic design are examined. In particular, with reference to eccentrically braced frames with intermediate links, starting from the shear-moment interaction diagram proposed by Neal, a procedure for calculating the ultimate shear forces and end moments of links is presented, for a given collapse mechanism. The requirements to be fulfilled are the yielding condition, the flow rule, the kinematic compatibility condition depending on the examined collapse mechanism and, finally, the minimization of the internal work according to the kinematic theorem of plastic collapse.
Moreover, through the definition of an equivalent moment, the link is modelled as an element with plastic hinges in simple bending. This is obtained by imposing the equivalence between the internal work developed by the actual link and the internal work corresponding to the simplified theoretical model. Therefore, the shear-moment interaction in plastic design is accounted for by means of formulations which are formally coincident with those commonly used for plastic hinges in simple bending.
Finally, the kinematic theorem of plastic collapse is used to define the design requirements to be fulfilled to prevent the yielding of the beam part outside the link and the yielding of the bracing element.
