ACI 446.4R-04 PDF Download

ACI 446.4R-04 is a standard that provides a comprehensive understanding of the dynamic fracture of concrete systems when subjected to rapid loading. The report serves as a valuable resource for engineers and researchers alike, offering recommended analysis approaches and material property selection.

In the report, it is highlighted that as strain rates increase beyond a certain threshold, concrete in both tension and compression exhibits increased strength and stiffness. However, it also shows reduced prepeak crack growth and decreased ductility in the postpeak region. The rate dependence of bond is attributed to localized crushing around bar deformations, which follows a similar relationship to compressive strength in terms of rate dependence. This localized crushing concentrates strains in a limited number of cracks, ultimately leading to reduced overall ductility in reinforced members.

Furthermore, the report emphasizes the importance of computational models that accurately capture the postpeak behavior under dynamic or static load. To achieve this, a localization limiter should be utilized in the models to prevent strain softening in arbitrarily small regions. Additionally, the equations of motion should be properly posed, and one way to achieve this is by incorporating rate-dependent behavior such as viscoplasticity to account for softening.