PSI - Issue 59

Mykhailo Hud et al. / Procedia Structural Integrity 59 (2024) 692–696 Mykhailo Hud et al. / Structural Integrity Procedia 00 (2024) 000 – 000

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1. Introduction To improve the precision of predicting the stability and resilience of structures under seismic loads, our approach involves the anticipation of natural frequencies and oscillation periods in the designed structure, following the methodology proposed by Bardell et al. (1997). The study delves into the analysis of forced oscillations exhibited by circular cylindrical shells, particularly focusing on scenarios involving two internal resonances and the principal resonance. The approach employs the multiple scales method to derive a set of six modulation equations. Additionally, a proposed method is applied to assess the stability of standing waves, and a continuation algorithm is utilized to examine the fixed points within the system of modulation equations by Avramov et al. (2007). The investigation into natural linear oscillations employed the finite element method (FEM), with contributions from Pellicano and Avramov (2007), Pradyumna and Bandyopadhyay (2008), and Yasniy et al. (2020). The parameters of damping elements based on SMA-alloys are presented in the paper (Iasnii (2020)). The goal of the article is to investigate and analyse the impact of mass distribution on the natural vibrations of a reinforced concrete building frame. The research aims to provide insights into how variations in mass distribution within the structural elements of the building frame affect its dynamic behaviour. By exploring the influence of mass distribution on natural frequencies and mode shapes, the article seeks to contribute valuable information for optimizing the design and structural performance of reinforced concrete buildings. 2. Modelling A finite element model of a 9-storey building with a reinforced concrete frame was created in the software package (Fig. 1).

Fig. 1. Finite element model of a multi-storey residential building.

The columns are modelled as rod elements. The floor slabs were modelled using shell-type finite elements. The columns are 40 × 40 cm in size, and the floors are 20 cm thick. Reinforcement of the structures was carried out in accordance with the requirements for strength and reliability. The joint between the columns and the slab is rigid. The connection of the columns to the conditional foundation is also rigid, and accordingly, movement in all directions is prohibited. Such fixings correspond to the actual operating conditions of such structures. The concrete class is C20/25, and the corresponding physical and mechanical characteristics were assigned to the reinforced concrete structures. The applied loads are the dead weight of the structures and the operational load. The study modelled situations of uneven mass distribution on the floor slab. In the first case, additional loads of 1 t/m 2 were set