Nonlinear seismic response of Milad Tower using finite element model

Milad Tower is a 436-m-tall telecommunications tower ranked as the fourth tallest structure of its kind in the world. The study of its seismic behaviour is of great importance as it is located in a highly seismic-prone region. Because of the existence of the world's largest revolving restaurant in the head structure, and also because of the highly sensitive communication devices such as TV and telecommunications antennas installed on the tower, nonlinear deformation under future earthquakes should be studied. In this paper, a detailed finite element model is developed and nonlinear dynamic analysis was carried out under the design earthquakes. The foundation, concrete shaft, head structure and 120-m antenna structure were modelled. Three components of the earthquakes are considered, and the selected earthquakes were normalized based on three design levels: design basis level, maximum design level and maximum credible level. The results of the analysis showed that all parts of the tower behave in the plastic zone except the elements of the head structure. It is also observed that in some cases, the earthquakes with lower peak accelerations and higher energy contents may have more severe effect on the tower than that with higher peak accelerations. Copyright © 2008 John Wiley & Sons, Ltd.