Finite element analysis on failure of reinforced concrete corner in sewage tank under opening bending moment

The paper discusses a failure mechanism of reinforced concrete (RC) sewage tank in a wall corner that failed during a filling test through excessive horizontal displacements of walls under opening bending moment. To explain the reasons for failure, comprehensive finite element (FE) calculations of the RC sewage tank were carried out under plane strain conditions. Concrete was modeled with a coupled elasto-plastic-damage constitutive model. The model was enriched in a softening regime by a characteristic length of micro-structure to provide the mesh objective results. FE analyses were performed for different arrangements of flexural reinforcement in the corner. The focus was on the evolution of strain localization and corner strength. Reasons for the tank failure were discussed. The FE results showed a high sensitivity of both the load bearing capacity of the tank wall corner and strain localization to flexural reinforcement arrangement. In addition, two laboratory experiments on RC corners subjected to opening bending moments were numerically analyzed under plane stress conditions.