Abstrakt

The high level of urbanization in the XXIst century forces the designers to design closely-separated structures and to take into account many factors influencing their response during seismic excitation, which are the most unpredictable loads which can affect civil engineering structures. Interactions between insufficiently adjacent buildings, known as the earthquake-induced structural pounding, may cause serious damage to the structures, leading even to its total collapse. The main reason of collisions between adjacent buildings during earthquakes, aside from insufficient distances between structures is related to the difference in dynamic parameters. The aim of this paper is to present the results of an experimental study of collisions due to insufficient separation gap between models of steel structures under earthquake excitation. To perform this study, models of three steel towers, with different dynamic parameters were constructed. To obtain the seismic excitation, the unidirectional shaking table, located at the Gdansk University of Technology (Poland), was used. To obtain different dynamic characteristics of structures, additional mass – concrete plates with the dimensions of 50x50x7 cm and 42.2 kg weight – were mounted at the top of each tower. In the experiment, two configurations of the towers were analyzed. The paper shows the results obtained for the configuration, in which two concrete plates were mounted at the top of external towers and only one concrete plate was mounted at the top of the middle tower. The influence of different separation gap (=0 mm, =20 mm, =40 mm, =60 mm) was taken into consideration. The results clearly indicate that insufficient in-between separation distance may result in interactions between buildings with different dynamic properties during earthquakes, leading to the change of their responses. The best behavior of structures has been observed for the case of zero gap size as well as when the gap size is large enough to prevent pounding.

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