ABSTRACT
Research related to RC has conventionally focused primarily on members and structures with few initial defects. The huge amount of currently available knowledge was mostly obtained in the laboratory, where well-controlled conditions can be provided. However, actual RC members are hardly ever exempt from initial defects. Some differences between real and laboratory RC members are demonstrated in Figure 7.1. Laboratory concrete members are normally so well nurtured that pre-cracking is minimized. By contrast, real RC members may remain in use under environmental conditions that may be grossly different from those available in the experimental room. As a result, concrete structures deteriorates with time. Moreover, during their life span, RC members may be subjected to unexpected non-proportional loading. Since concrete is a path-dependent material that memorizes loading history, previous loading may result in cracking, stress/strain states and residual deformation, which may play a crucial role in the next loading stage.
