Assessment of the floor response spectra due to pounding between adjacent structures during earthquakes: an alternative approach to study local amplifications

B. Bodnar (1) , T. Heitz (2) , J. Clément (2) , B. Richard (2)

1 LMSSC - Laboratoire de Mécanique des Structures et des Systèmes Couplés
2 IRSN/PSN-EXP/SES/LMAPS - Laboratoire de Modélisation et d’Analyse de la Performance des Structures

The capability of equipment classically used in nuclear facilities to withstand dynamic loadings (earthquakes, impacts, pounding, falling of heavy objects, etc.) is a major concern. In order to ensure their correct design, it is necessary to assess, beforehand, the admissible load. However, the validity of the spectral modal analysis (SMA) largely used in the community can be legitimately questioned since it does not account for local high dynamic phenomena and is strongly dependent on the choice of parameters to get a satisfactory assessment of the calculation results. In this paper, the case of pounding loading is studied. An alternative approach to describe pounding between two adjacent structures during earthquakes is proposed, in order to evaluate the floor response spectra (FRS). The loading demand is then evaluated at the bottom of an equipment located on the floor of a building, from a step-by-step calculation by performing a SMA. To do so, the contact forces are first assessed using linear beam models with the same modal characteristics as the ones of the building under study. Then, the pounding loading is applied on a three-dimensional mesh of the first structure made from shell and beam elements. The results highlight propagation of shock waves and underline local amplifications of the FRS at the edges of floors. The loading demand given by the SMA shows that the error related to the step-by-step calculation decreases when pounding is taken into account. It turns out that the contact loading leading to a horizontal movement reduces the influence of floor rotations and increases when the damping of the structure is low, especially in the high frequency range. With an error of less than 10%, the SMA method may be regarded as acceptable in case of pounding between adjacent multi-story buildings.

Mots clés: Civil engineering; Earthquake engineering; Numerical simulations; Pounding between structures; Floor response spectra; Response spectrum analysis

Domaines: Sciences de l'ingénieur [physics]

B. Bodnar, T. Heitz, J. Clément, B. Richard. Assessment of the floor response spectra due to pounding between adjacent structures during earthquakes: an alternative approach to study local amplifications. Engineering Structures, 2022, 255, pp.113922. ⟨10.1016/j.engstruct.2022.113922⟩. ⟨hal-03727499⟩