| Restraint temperature and shrinkage strains are one of the major reasons for cracking of reinforced concrete. Cracking of concrete reduces structural integrity, initiates or accelerates deterioration mechanisms, causes serviceability problems and may raise esthetical concerns. Particularly for liquid retaining structures, cracks are vital for structural functionality. Measures must be taken to prevent or control crack. In most cases, it may not be feasible to prevent crack formation, but crack width can be controlled by providing sufficient amount of reinforcement. Design guides provide limited information on adequate reinforcement ratio for temperature and shrinkage cracks. Optimized reinforcement design for temperature and shrinkage cracks requires additional guidelines. This study deals with temperature and shrinkage cracks in reinforced concrete structures. The Finite Element Method (FEM) was used in order to investigate the crack risk, magnitude of crack width, and adequate reinforcement ratio for controlling cracks within the design specifications. In order to find the thermal and shrinkage strains effect during early ages, computer simulations was performed for hardening concrete. Using the computer program ABAQUS/6.4, incremental numerical analysis technique was implemented that provided realistic simulation of stress/strain history. Considering an appropriate value for thermal and shrinkage strains, a parametric study was carried out to estimate the reinforcement ratio for fixed base walls. The crack width was estimated based on the calculated steel stress and the ACI 318-02 crack prediction equation. With consideration of ACI 350-01 specification for allowable crack width, the required amount of reinforcement ratio for various wall dimensions was recommended. |
