Ductility requirements in shear bolted connections

Abstract

This thesis presents ductility requirements for actual shear bolted connections. The presence of imperfections in the fabrication process (as bolt diameter, hole diameter, bolt alignment,…) can lead to situations where some bolts bear against the plates before the others due to misalignment. The global behaviour of the connection is then affected and more deformation capacity is therefore required locally. With the purpose to evaluate the imperfections in bolted connections, analytical work, based on the standards for execution of steel structures was done and the so-called “worst” situations (layouts) were defined. From these, maximum gaps between the bolt and the hole edges were obtained and used to determine the new demands of ductility. The component approach prescribed by Eurocode 3 part 1.8 was applied in the analysis of the connections. Three basic components were identified: the plate in tension, the bolt in shear and the plate/bolt in bearing. The bolt in shear and the plate/bolt in bearing were assembled and treated as the equivalent bolt zone component. The presented work is focussed in the equivalent bolt zone component. Parallel to the analysis of the global behaviour of the connections, work was done on the basic components. Based in experimental work, formulae to express the behaviour and to determine deformation capacity of the bolt in shear component were derived. A numerical model to evaluate the plate/bolt in bearing component is also presented. Experiments on shear bolted connections made of High Strength Steel were used to validate the model. Analytical work was done in the assembly of the basic components and formulae to evaluate the available and the required deformation capacity, at the equivalent component for a full plastic resistance of the connection, are proposed. Finally, a ductility criterion for actual shear bolted connections, based on the local (equivalent bolt zone component) available and required deformation capacity, was derived.