Many actions, such as accidental or malicious explosions, may impose high loading rates to structural frames. To enhance the knowledge of the behaviour of joints subjected to severe impulsive loading, a double-sided beam-to-column joint configuration was tested at quasi-static and dynamic loading rates. The test specimens consisted of H-section beams and columns, extended end-plates, and high-strength bolts. In both the quasi-static and dynamic tests, the fracture modes were bolt failure in combination with plastic deformation of the end-plates. However, it was observed that the joints absorbed considerably more energy before failure in the dynamic tests than in the quasi-static tests, partly due to changes in the deformation modes. Also, the ductility of the joints seemed to increase for higher loading rates. These results suggest that the tested joints behave in a preferable manner under extreme impulsive loads.

Thread failure of bolt and nut assemblies subjected to tension is generally undesired because it is a less ductile failure mode than fracture of the threaded shank of the bolt (denoted bolt fracture).Another issue is that incipient failure of the threads due to over-tightening is difficult to detect during installation. Thus, it is appropriate to investigate the causes of thread failure. A parameter that seems to govern the failure mode of bolt and nut assemblies, despite receiving limited attention in the literature, is the length of the threaded bolt shank located within the grip. This is particularly relevant for partially threaded bolts, where may be short. In the current study, direct tension tests were performed on M16 bolt and nut assemblies with different lengths . The tests showed that ≤ 9 mm resulted in thread failure, whereas ≥ 17 mm resulted in bolt fracture.For the intermediate range of , both failure modes were observed in replicate tests. Validated finite element simulations were conducted to gain insights into the mechanisms of failure. When was short, necking of the bolt occurred close to the nut so that the overlap between the threads of the bolt and the nut was reduced, which further induced thread failure. This paper suggests several practical approaches for reducing the probability of thread failure.

Limited documentation is concerned with the behaviour of steel joints subjected to severe impulsive loading originating from incidents such as explosions or impact. In this paper, finite element simulations are used to investigate the behaviour of beam-to-column joints with bolted end-plate connections subjected to impact loading. An elastic-thermoviscoplastic material model was employed in the simulations. Good agreement was obtained between the simulations and previously reported tests in terms of both global and local behaviour. In particular, the numerical model successfully reproduced the experienced failure mode of tensile bolt fracture combined with end-plate deformation. The validated model was employed in investigations of three cases, in which the main findings are as follows: 1) reducing the end-plate thickness significantly increased the energy dissipated by the joint; 2) axial forces in the beams only marginally affected the response; and 3) including the additional inertia introduced by the presence of floor slabs may change the failure mode to premature shear failure.

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2]. The duplicate publication of this article was due to an administrative error on the part of the publishers. The authors were in no way at fault. For the version of record, please refer to the first published version [2]. The publishers wish to apologize for this error.