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Behaviour of T-STUB under mode 2 and 3 with HV and HR bolts
No full textThe behavior of the bolts can strongly influence stiffness, strength, and ductility of joints. The current Eurocodes allows using both HV (German type with failure by nut striping) and HR (British-French type with failure by necking of the shank) bolts without making any distinction between them. However, recent studies showed that these two types of pre-loadable bolts are characterized by different ultimate tensile behavior that could lead different joint ductility. The aim of this work is to investigate the influence of the type of pre-loadable bolts on the behavior of T-stubs when it is subjected to mode 2 and 3. To this end, analytical and numerical analyses were carried out. The results show that only in case of the failure mode 3 some differences can be observed between HV and HR
Influence of Transvserse Beams On the Ultimate Behaviour of Seismic Resistant Parrtial Strength Beam-To-Colummn Joints
No full textThe most of existing numerical and experimental studies on seismic resistant steel beeam-to-coluumn joints were carried out on planar assemblies, thus disregardding the presence of transvverse beams that typically resist gravity loads in multistorey buildings. In this article, the influence of the transverse beams and their shear connections on the ultimate response of partial strength beam-to-collumn joints is investigated under cyclic actions and column loss scenarios by meeans of finite element simulations. The results show that the presence of the transverse beams provides minor beneficial efeffects on the primary moment resisting joints under seismic actions. On the contraary, the presence of th e transverse beams gives significant effects in the case of collumn loss scenario, where large plastic deforrmations developp following the activation of catenary effects iin the connected members
FREEDAM connections: advanced finite element modelling
No full textFREEDAM connections consist of a symmetric friction device connecting the lower flange of the beam to the column by means of L-Stubs. This assembly prevents the damage of the connected members and dissipates energy by means of the slippage between the clamped steel elements and the friction pads of the device. In order to characterize the monotonic and cyclic performance of the joints equipped with friction dampers a comprehensive and extensive parametric finite element (FE) simulations have been carried. The FE models have been validated against the experimental results of the tests carried out within the FREEDAM project. The performed FE analyses allowed evaluating the response of both external and internal joints with the FREEDAM devices. In addition, different geometries of the friction dampers and the relevant beam-column assemblies have been investigated. The FE analyses confirmed the effectiveness of the design assumptions and the satisfactory performance of the investigated joints
Experimental and numerical study on the T-Stub behaviour with preloaded bolts under large deformations
No full textThe bolts and their arrangement strongly influence stiffness, strength and ductility of T-Stub connections. Preloaded bolts are typically adopted to improve the stiffness and limit the opening of the connection under serviceability conditions. EN1993-1-8 allows using two types of high resistance preloaded bolts, namely the German HV (acronym of Hochfeste Bolzen mit Vorspannung, which is the German for High Resistance bolts for pretension and the British/French HR (acronym of High Resistance) without making any distinction. However, the tensile failure modes of these bolts are different (i.e. nut stripping for HV and shank necking for HR) and may affect the ultimate tensile response of the T-Stub connections with weak bolts (e.g. failure mode type 2 and 3). Furthermore, despite the effects of geometrical non-linearities at large deformations are not specifically addressed in current codes, the membrane action developing in the flange and the shear force and bending moment in the bolt may influence the reserve of ductility of the T-Stub that plays an important role in case of seismic and robustness scenarios. In addition, the presence of initial imperfections (e.g. the misalignment of the web as respect to the bolts and the flange bowing) can influence the non-linear behaviour of the connection. The influence of all these aspects on resistance and ductility of T-Stub connections are investigated by means of both experimental monotonic tests and parametric finite element analyses. On the basis of the obtained results, design rules are discussed with the aim to guarantee extra ductility of T-Stub connections
Un Approccio Integrato per la Gestione della Sicurezza negli Apparati Sperimentali Complessi
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