The selection of methods for strengthening of the reinforced-concrete structure of the open tank

The paper presents the solution to the selection of methods for strengthening a reinforced concrete wall of an open tank structure, located in a sewage treatment plant. Originally, this construction was reinforced with three massive retaining blocks topped with a beam. The reason for designing additional reinforcement of the wall structure was the damage in the form of cracks parallel to external walls observed during the implementation of the tank tightness testing in 2002. The measured cracks had a variable width up to 4.1 mm. The cause of the resulting damage was insufficient cross-section of the bottom plate reinforcement in the areas of connection with the walls. During the expansion of the sewage-treatment plant in 2014, additional bioreactor tanks were designed in the vicinity of existing retaining blocks. This implied the necessity to remove the supporting, retaining blocks and to make a new reinforcing structure. Several strengthening solutions have been analysed taking into account the continuous operation of the sewage treatment plant as well as the design variants that do not interfere with the interior of the existing tank chamber. A solution in the form of a support structure anchored on a palisade of bored piles was adopted.