Analysis of the Earthquake Load Effects on the Cooling Tower Structure of the Ulumbu Geothermal Power Plant Using the Pushover Method

Abstract

Earthquake loads pose a critical threat to the structural integrity of infrastructure in geothermal power plants, particularly cooling towers, which are essential for thermal regulation. This study aims to evaluate the seismic performance of the cooling tower structure at the Ulumbu Geothermal Power Plant through a nonlinear static pushover analysis. The analysis was performed using structural modeling software and applied the ATC-40 guidelines to assess performance levels under lateral seismic loads. The capacity spectrum method was utilized to transform the pushover curve into an equivalent single degree of freedom (SDOF) system, allowing the identification of the performance point. Results indicate a proportional relationship between base shear and displacement, with the structure capable of resisting a maximum lateral load of 730.383 kN. According to ATC-40 criteria, the structure meets the Immediate Occupancy (IO) performance level, demonstrating sufficient seismic resilience and indicating that the cooling tower remains safe and operational following a moderate earthquake. This research contributes to the understanding of seismic vulnerability in geothermal infrastructure and supports improved structural design and risk mitigation strategies.