Developing a numerical model for a UK intake tower seismic assessment

This paper describes a case study conducted as part of a broader project investigating the seismic risk to appurtenant structures to dams in Scotland. The study concentrates on Loch Glascarnoch intake tower, a reinforced concrete structure representative of other similar towers in the region. The seismic risk to these towers and an appropriate method of numerical modelling for their seismic analysis is investigated. Ambient vibration tests were conducted on the tower to determine its modes of vibration. The fundamental bending mode had a frequency of 5·8–6·0 Hz, demonstrating the potential for a significant dynamic response to a typical earthquake for the region. The effect of amplified accelerations on the gatehouse, and the equipment stored within, would need to be considered as part of the complete seismic assessment of the tower. A finite-element (FE) model of the tower was developed for its preliminary seismic analysis. This was a relatively simple 3D solid model with a coarse mesh. A very good correlation between the modal properties from the tests and analysis of the model demonstrated that the FE model provided a valid basis for the development of a more sophisticated model for further analysis, if required.