Investigation of pounding behavior of adjacent buildings using numerical methods and shake table experiments

In highly populated cities, when buildings are closely positioned and lack sufficient seismic gaps between them, additional cross-sectional effects can occur during earthquakes. These effects, caused by the collision of adjacent buildings, are often not considered during the analysis and construction of such structures. When seismic gaps are inadequate, these buildings can cause significant damage to each other and even lead to destruction. In order to analyze such effects, pounding models have been proposed in scientific literature. It is crucial to determine the parameter values of these models, which consist of spring and damping elements. This study considers different building models to investigate the effects of adjacent, insufficient seismic gaps and separate positioning combinations under harmonic excitation and earthquake effects. The study uses the Kelvin-Voigt Model, which comprises spring and damping elements, for numerical pounding analysis. The critical parameters of the Kelvin Voigt model spring stiffness (ks) and damping calculated according to the restitution factor (r) are analyzed and compared with experimental results under harmonic excitation and earthquake effects. For comparison, several numerical simulations with different spring stiffnesses and restitution factors are performed. The study presents two different examples. The first example involves two 3-story shear frames positioned adjacent and separately, while the second involves combinations of 1, 2, and 3-story shear frames positioned for adjacent, separate, and insufficient seismic gaps. In Study 1, the numerical analyses show compatibility with earthquake simulations when the restitution factor is set at 0.2 or 0.4 and the ratio of spring stiffness to shear stiffness (ks/k) is 1 or 5. In Study 2, when comparing models with an equal number of stories under earthquake effect, the spring stiffness in the adjacent scenario is determined as 0.5k and k. In cases where there is a gap of 3 mm, the spring stiffness is determined as k, 5k, and, to a lesser extent, 0.5k and 10k. Although it varies for other combinations, the spring stiffness increases to 100k. When the restitution factor is examined, it is seen that there is a good agreement in the analysis results when r = 0.6-0.8. In the specific case of this study, when there is an insufficient earthquake joint between the models, the resulting pounding forces increase by up to 6 times more than when the models are adjacent.