Effects of Semi-Rigid Connection on Structural Responses

There are several idealizations in numerical analysis of structures. In the joints and supports, which is usually assumed to be pinned or rigid, semi-rigid connection should be considered to obtain more realistic, reliable and also economical results. In this study, rotational spring stiffness-connection ratio relation is clearly explained and revealed. A finite element program SEMIFEM is developed in FORTRAN language for the numerical analysis. This program provides to define semi-rigid connections in terms of rotational spring stiffness or connection ratio simultaneously. In the numerical applications, rotational spring stiffness - connection percentage relation of the semi-rigid connected structural members is submitted. Semi-rigid connections are considered in column-to-foundation connection of a portal frame, beam-to-column connection of a prefabricated structure, steel brace connection to reinforced concrete (RC) frame of a steel X-braced RC frame and truss member connection to joint of a steel truss system. The variation of moment, shear force, axial force, displacement and stress is investigated in a selected axis of the structures. Numerical examples are performed with respect to connection percentage of the related structural members by using finite element method. According to finite element analysis results, the degree of the semi-rigid connection is important as much as its existence in the design phase. This study reveals that the effect of semi-rigid connections on structural systems shows different variations from structure to structure.