Advanced finite element modelling of stainless steel bolted T-stubs under large deformations

Following upon the recently published experimental and numerical studies on stainless steel bolted T-stubs in tension, this study reports the development and validation of an advanced FE model that reveals the effect of initial contact between the bolts and bolt holes and constructional imperfections on the response of stainless steel bolted T-stubs subjected to large deformations. Key simulation strategies regarding the modelling of bolts, initial position of the bolts, flange bowing effect due to the initial constructional imperfections and overcoming numerical instabilities are discussed. The developed FE model first validated against the available test data in the literature. The effect of pre-established contact between the bolts and bolt holes and constructional imperfections on the overall response of the bolted T-stubs are reported comprehensively by comparing the plastic and ultimate resistances with the experimental ones. Moreover, the membrane action developing in the flange influences the ductility reserve of the T-stub which has a vital role in case of progressive collapse and robustness scenarios. Therefore, by inspecting the stress distribution through the flange thickness at various locations along the T-stubs, effects of different modelling configurations on the flexural and the membrane component of the load transfer mechanism are revealed. A parametric study is performed to investigate the influence of all these aspects on resistance of T-stub connections. On the basis of the obtained results and the discussions, modelling recommendations for the simulation of stainless steel T-stubs are made.