Development of Wind Induced Fragility Curve for Elevated Service Reservoirs

Elevated Service Reservoirs (ESRs) are critical components of water distribution systems and must be capable of withstanding extreme loading conditions. This paper presents a comparative fragility analysis of circular and rectangular Elevated Service Reservoirs subjected to lateral wind loading. Three-dimensional numerical models of both ESR configurations were developed and analyzed using ETABS software. Fragility curves were generated based on predefined damage states, namely slight, moderate, severe, and collapse, to assess the probability of structural damage under increasing load intensity. The analysis considered structural response parameters such as storey displacement, storey drift, and damage exceedance probability. The results indicate that the circular Elevated Service Reservoir exhibits lower vulnerability and superior structural performance compared to the rectangular Elevated Service Reservoir due to its uniform stress distribution and reduced susceptibility to stress concentration. Furthermore, the circular geometry demonstrated enhanced structural reliability and resilience under lateral loading conditions. The findings highlight the effectiveness of circular water tank geometry in improving the performance of elevated water storage structures and provide valuable insights into fragility curve development and probabilistic structural assessment.