Fundamental principles of the reinforced concrete design code changes in Chile following the Mw 8.8 earthquake in 2010

The Mw 8.8 earthquake in 2010 in Chile provided valuable information regarding the damage and potential design code changes for reinforced concrete (RC) structures. Many modern RC buildings suffered severe damage, mainly in the form of concrete cover spalling, followed by longitudinal boundary bar buckling and concrete crushing. The absence of wall boundary detailing explains such behavior, but older structures and thousands of other buildings suffered minor or no damage at all. An analysis of some potential factors that influenced the damage caused is carried out and the fundamental principles for the Chilean RC design code changes are exposed. Currently, a displacement-based approach is used for detailing of the wall boundary elements as well as for establishing damage limitation. Compressive concrete strain cannot exceed 0.008, limiting indirectly the axial load, which is one of the potential precursors of the damage. Transversal reinforcement is also provided in zones of potential yielding of the longitudinal reinforcement such that buckling due to compression preceded by tension is minimized; this buckling is more likely in asymmetric cross-sections, such as T-shaped sections, where usually the web goes into larger tensile and compressive strains given the variation of location of the neutral axis for the web under tension or compression.