Mechanical modeling of bolted T-stub connections under cyclic loads Part I: Stiffness Modeling

This paper deals with mechanical models which make it possible to reliably simulate the complete moment–rotation curves in the full-scale T-stub connections subjected to cyclic loads. The behavior of these bolted connections becomes complex because the various response mechanisms of individual connection components interact with one another and have influence on the overall rotational stiffness of the connection. Accordingly, the mechanical joint models are made up of individual T-stub components modeled as nonlinear springs. The behaviors of component members including tension bolt uplift, bending of the T-stub flange, elongation of the T-stem, relative slip deformation, and bearing deformation are reproduced by the multi-nonlinear stiffness models obtained from their force-deformation response mechanisms. These stiffness properties should be assigned into the component springs implemented into the joint element so as to numerically generate the behavior of full-scale connections with considerable accuracy. Thus, this part (Part I) intends to focus on describing the stiffness models, which are based on the basic component spring theory, in an effort to provide insight into the behavior, failure modes, and ductility of T-stub components in the connection.

Research Highlights
► Mechanical models to simulate the cyclic behavior of T-stub connections.
► Multi-linear stiffness models to predict the cyclic behavior of components.
► Failure modes occurring at individual T-stub components.
► Connection components modeled as nonlinear component springs.
► Response mechanisms which have an influence on the overall stiffness of connections.