Seismic performance evaluation of an ATC tower through pushover analysis

Air traffic control (ATC) towers are a vital form of infrastructure that controls the landing and taking off of airplanes at every airport. In spite of the significant role that ATC towers play during disasters like earthquakes, little attention has been paid to their seismic behavior. In this study, the seismic performance of an existing ATC tower with a dual lateral-load resistance system was evaluated through pushover analysis. The tower was pushed by two different lateral-load patterns and the performance points were calculated accordingly. It was observed that when the applied lateral load follows the pattern obtained from the response spectrum analysis, the maximum displacement demand is twice that of the mass-proportional lateral-load pattern. The drift values indicate that the tower suffers from low lateral stiffness at its higher levels. It was also found that at the target displacement the longitudinal reinforcements in the internal concrete core reached yield stress. The results of the plastic hinge formations show that the steel frame satisfies the requirements of the immediate occupancy (IO) performance level. The stress values in the concrete of the external walls were found to be less than the design values