Strengthening of the reinforced concrete tank of anaerobic purification plants with the manufacture of biogas, damaged as a result of design and construction errors

Abstract

Abstract The defects and damages of bearing structures (walls, covering) of the solid-cast reinforced concrete tank were identified and detected using visual and instrumental testing. The actual reinforcement of the tank was determined and coordinated with designed reinforcement. Furthermore, the deformations were measured, the cracks opening in the walls and its depth in the concrete were detected and was also the strength quality of concrete was defined. During the year of the operation, the tank developed a considerable system of cracks in all lateral walls from technological loadings. At the same time, the width of the crack opening exceeded the limit values for reinforced capacitive structures (wk), which is equal to 0.1 mm. The walls lost tightness, the use of the structure in the technological process was suspended. Checking calculations of the design solutions was carried out for the elements of the tank on technological loadings in the software package LIRA to find the causes of the cracks opening and water penetration in the walls of the reinforced concrete tank. It was determined that the existing design solutions did not ensure the bearing capacity and the fracture strength of bearing reinforced elements of the tank and its spatial rigidity from technological loadings. Necessary reinforcement was defined by ensuring the strength and possible limitation of the width of the cracks opening. This article presents the technical solutions concerning the strengthening of repair bearing elements of reinforced concrete spatial frame of the existing structure. The external bandages (reinforcing steel 4d32A400C) and inner tension bars (stainless steel round pipes 168 x 5 mm) were used as the strengthening of the reinforced concrete tank.