Influence of Supporting Joints Flexibility on Statics and Stability of Steel Frames

Abstract

The paper presents an influence problem of the rotational flexibility of supporting joints on steel frames behaviour. A substantial part of the paper is devoted to, neglected in the engineering practice, issue of rotational flexibility of the foundation-subgrade system. This problem was analyzed on the assumption that the foundation in the form of a rectangular rigid punch rests on a homogeneous medium of finite depth. Suitable analyses of the foundation were done using several subgrade models: Winkler’s model, elastic half-space (in the classic approach) and with the use of the boundary element method, as well as HS model (hardening soil) by application of the finite elements method. The phenomenon of rotational flexibility of footings resting on a soil subgrade was analyzed within the linear range. It was shown, that the practical assessment of rotational stiffness of footings resting on subgrade can also be performed by using simple methods (e.g., based on the Winkler’s model). The presented evaluation methods of the whole flexibility supported joints were used in the static and stability analyses of the certain steel frame. The presented results confirmed a significant influence of the flexibility of the supporting joints on the steel frames behaviour.