PSI - Issue 73

Přemysl Pařenica et al. / Procedia Structural Integrity 73 (2025) 125 – 129 Přemysl Pařenica and Petr Lehner / Structural Integrity Procedia 00 (2025) 000–000

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to-weight ratio, ease of manufacture and cost-effectiveness, it offers an alternative to traditional structural materials. The material savings in the construction and the simplicity of the whole system brings with it many advantages, as well as the application of automation areas (Flodr et al., 2014; Obeydi et al., 2021). An important area is the application of high thin-walled purlins of 300 heights, which can be used for large spans, but which bring with them various problems and issues. The load-bearing capacity of these structures depends significantly on the load-bearing capacity of the details - the connection with the supporting structure and the mutual connection of the individual thin-walled elements. Therefore, the use of additional structural elements such as local bracing, stabilising elements and supports, as well as other structural measures such as doubling of profiles or changes in material thickness, are necessary for thin-walled structures. It is essential to ensure that the designed connections do not cause local instability and are sufficiently rigid and load bearing. 1.1. Comprehensive research programme Previous studies by the author's team have focused on the structural behaviour and design of tall, thin-walled, cold formed steel Z-section purlins, which are components of long-span steel structures. The studies mainly demonstrated a combination of experimental tests and numerical modelling based on the finite element method. Different aspects of plate behaviour, connection details and the influence of design parameters were investigated (see example in Figure 1). These studies provided a thorough summary of the experimental program (Pařenica et al., 2023) , but also a detailed description of all the developed and optimized numerical models together with their verification (Pařenica et al., 2024, 2021). However, all these studies included the results of two connections options: without a reinforcement clip or with a reinforcement clip rigidly connected by a bolt to the purlins. However, a significant and hitherto neglected in the numerical analysis is the variant of the connection with a clip not attached to the purlins itself. Therefore, a finite element model was prepared for this paper to analyse the third and as yet unstudied variant.

Fig. 1. Visualization of the purlins set for the load test, from which the geometry for the numerical models was based.

1.2. Different connection concepts The connection of thin-walled purlins to the supporting structure has several possible solutions, regardless of the type of connecting means (Gutierrez et al., 2011; Pařenica et al., 2024; Tomà et al., 1993) . Figure 2 shows 3 connection options.

Fig. 2. Variants of connection of thin-walled roof trusses: (a) without clip, (b) with reinforcing clip and gap, (c) with reinforcing clip and direct connection.

Variant (a) is a simple connection without a reinforcing clip, applicable only for very low purlins with small spans and small roof plane slopes. Option (b) uses a clip with reinforcement. In the classical clip solution, a gap is always