PSI - Issue 81

Mykhailo Hud et al. / Procedia Structural Integrity 81 (2026) 486–492

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capturing dynamic response parameters. Overall, existing literature affirms that even modest architectural and structural changes may substantially alter the dynamic behaviour of multi-storey buildings. The current study contributes to this field by presenting detailed FEM-based modal analysis of several plan-asymmetric configurations, highlighting the sensitivity of frequency characteristics to openings and asymmetric extensions. 2. Modelling The building frame was modelled in the LIRA finite element analysis software environment, which facilitates detailed representation of the spatial behaviour of structural systems while accounting for their geometric and physico-mechanical characteristics. The geometric parameters of the structure are 8 × 8 m in plan, with each storey measuring 3 m in height. The total height of the building is thus equivalent to nine storeys. The computational spatial model was constructed using three-dimensional finite elements with a discretisation step of 10 × 10 cm. This level of refinement allowed for an accurate reproduction of the geometry of the load-bearing frame elements and ensured the correct determination of stress – strain characteristics under dynamic loading conditions. Reinforced concrete of class C20/25 was selected as the primary structural material of the frame, with physico-mechanical properties that meet the requirements for typical civil and industrial frame systems. This choice enabled the development of a representative model consistent with realistic operating conditions and suitable for reliable assessment of the building’s dy namic and static characteristics.

Fig 1. Basic frame model

In addition to the baseline computational model (Fig 1.), several alternative structural configurations of the frame were analysed in the study, aimed at assessing the influence of modifications in the layout solutions on the spatial behaviour of the structure.