Assessment of the structural health monitoring of a reinforced concrete water tower

Abstract

The Reinforced Concrete Water Tower at the Abattoir in Marsa was in a deteriorated state before an extensive restoration intervention was carried out. The restoration process included restoring the deteriorated water tank and support columns, using ultra high-performance concrete and textile reinforced concrete. A structural health, durability and environmental monitoring system was set up at the Water Tower. Throughout the restoration process, numerous sensors were included in different parts of the water tower, including the columns and in different parts of the tank. The sensors are intended to monitor different durability and structural health characteristics of the restored water tower. These include sensors that would analyse the structural integrity of the water tower and also the performance of the concrete: resistivity, galvanic and electrode durability sensors to analyse the durability of the water tower under various conditions in use. Environmental monitoring was also set up with a weather station which captures data on weather conditions including solar radiation, temperature and precipitation and their effect on the water tower. The aim of this dissertation is to analyse the data obtained from the structural health and durability sensors to understand the way the restored water tower reacts to various conditions, and to see how the condition of the water tower develops with time while in use. This was done by obtaining the data from the extensive sensor system (150 sensors), analysing it and interpreting using different techniques to understand the performance of the structure. The water tower was primarily analysed during the filling in and emptying of the water tank with 400 cubic m of water, which took place during September 2021 before starting this dissertation, as it was crucial to understand how the structure reacts during these critical processes. The performance of the structure during a seismic event was also assessed with reference to the sensor system. In addition, the performance of different sensors in different parts of the structure during different scenarios was analysed. Overall, the results obtained when analysing the structural health monitoring system (strain gauges, accelerometers) and durability sensors on the water tower indicated that the systems are capable of assessing the performance as anticipated at design stage of the monitoring system. In addition, the system indicated that the structure was performing as per design considerations, when considering behaviour at different stages of use of the structure, including before filing in, full of water and on emptying the tank. Observing the water tower’s performance over time through the durability sensor system permits an understanding of the effectiveness of the restoration and the durability of the restoration and strengthening methods employed themselves, which will help to contribute to the development of restoration processes for other reinforced concrete structures in deteriorated states similar to the water tower.