Numerical validation of LRPH behaviour by FEM analysis

LRPH connection is a special steel device mainly usable to join beam elements of plane or spatial steel frames. It is identified as Limited Resistance Rigid Perfectly Plastic Hinge and it is covered by patent n. 102017000088597 at the Italian Ministry of Economic Development and identified in the International Patent System with the number PCT/IB2018/055766. The fundamental innovations of this device are the mutual independence of their own resistance and stiffness features and the respect of assigned constraints related to the elastic and limit behavior of the joined elements. Within the frame structural scheme, the device plays the role of a rigid perfectly plastic hinge, and it is constituted by a sequence of three steel elements of limited length bounded by two parallel steel plates joined up with the connected structure elements. The cross-sections of the steel elements are I-shaped with specific thickness and length obtained by a suitable optimal design. The efficient use of the LRPH in the relevant frame substantially depends on the appropriate design of the device geometry carried out taking into account only bending moment. Starting from an assigned geometry of the LRPH fulfilling some suitably fixed behavioral data, the present paper is devoted to numerically investigate on the reliability of the device by utilizing appropriate FEM analysis. In particular, the yield conditions and the kinematical performance of the device are investigated. The obtained results, related to some common standard steel profiles, confirm the wide applicability of the LRPH in the field of steel structures.