Progressive collapse of building structures induced by accidental extreme loads has garnered significant attention. This study aimed to assess the impact resistance of steel-framed subassemblies with extended reverse channel connections under falling debris impact. It also sought to provide technical support for anti-collapse design. Drop-hammer impact tests were conducted to obtain baseline data. A validated finite element model using ANSYS/LS-DYNA was employed for the parametric analyses. The key parameters investigated included the impact location (mid-span vs. beam end), falling height of the impactor, and span-to-depth ratio of steel beams, with a focus on the impact resistance. The results reveal that the impact resistance depends on both the peak load capacity and the deformation capacity. The mid-span impacts exhibited higher resistance at falling heights ≥ 1.0 m due to greater plastic deformation. In contrast, the beam-end impacts performed better when the falling heights were ≤0.5 m. The impact resistance decreased with an increasing falling height. The reduction ratios exceeded the theoretical values due to the post-impact gravitational energy input. Smaller SDRs enhanced the peak resistance under both impact scenarios, with more pronounced effects in the mid-span cases. Catenary action significantly improved the mid-span impact resistance (19.3–66.7%). However, it contributed minimally to the beam-end impact resistance (0.61–1.09%), where shear action dominated. These findings offer critical technical support for optimizing steel structure designs to resist falling debris impact and enhance overall structural robustness.

The paper continues the past research on the screwed thin-plate single-lap connections undertaken by the author. This re-search was focused on stressed skin diaphragm action, where it is essential to know values of connections behavior. Until now, initial stiffness is used for common engineering estimations. The main aim of this paper is to compare the experimental results of the shear tests conducted on the connections with the theoretical predictions of their initial behavior obtained from the FEM models. The experiments followed the Eurocode rules for design aided by testing and the European Convention for Constructional Steelwork (ECCS) recommendations. FEM parametric models are introduced as a consideration to use, taking into account screw threads and EPDM washers. In the technical literature, various techniques are described for the modelling of threaded connections. A modification to a known solution is applied in this analysis where a spiral thread is substituted by simple horizontal rings; this simplification allows use of symmetry in a static system, which is particularly desirable for large models such as those prepared in this paper. In contrast to the mentioned known solutions, the thread mod-el presented here has a triangular cross-section related to the geometry used in real screws. The numerical results correspond reasonably well to the test’s early stage measurements from the lab experiments and can be useful for initial stiffness examination (e.g. where no data is provided for a particular connector by a producer) or as a base to further research on the model.

This publication outlines the principles for evaluating the load-bearing capacity and fatigue performance of bolted flange connections in accordance with the provisions introduced by the second generation of Eurocodes. The proposed assessment procedures are compared against the methodologies traditionally applied in Polish engineering practice

In this paper, the results of a research on thin-plate single-lap connections are presented. Such type of connections is popular in steel roofs made of trapezoidal plates and other thin-walled elements. In case of a building safety it is necessary to ensure that materials with proper durability and ductility are used. Connections are one of the most important components in such structures, particularly when in-plane strength of a roof is taken into account. So far, in many existing regulations, only general calculations of such connections are conducted. However recently, discrete and computational methods can be used to build new, expanded mathematical design models, such as those presented here. Such models could be useful in an advanced design where a static analysis is combined with the safety assessment of the connections in a structural system. This is difficult when sheeting is utilized as a structural in-plane shear diaphragm. These require to take into consideration the important interactions of structure with covering and covering with another covering elements. The research is an effect of authors works on practical design approaches. Such methods can be effectively used for structural designs of buildings where the stressed skin diaphragm action is involved. Finally, practical input values about connections can be acquired from the presented data.