Structural Design Methodologies for Concrete Pipes with Steel and Synthetic Fiber Reinforcement

Improved structural designs were developed and experimentally verified for concrete pipes. These designs make effective use of discrete synthetic fiber reinforcement to lower the reinforcing steel ratio, and thus allow for increasing the protective cover of concrete on steel for improved durability. The new concrete pipe design also enhances the toughness and damage resistance of pipes. The work reported herein covers theoretical modeling, design, and experimental verification of concrete pipes with synthetic fiber and conventional steel reinforcement. The focus of the theoretical models was on the flexural strength and load-carrying capacity of concrete pipes. These models account for the contributions of fibers to the tensile behavior of concrete via fiber pullout or rupture. These models were used to develop new concrete pipe designs, which made complementary use of synthetic fiber (polyvinyl alcohol [PVA]) and conventional steel reinforcement. Full-scale pipes embodying the new design were fabricated and experimentally evaluated. The experimental results were used to refine the theoretical models and design procedures. Test results confirmed that the number of steel reinforcement layers in concrete pipes can be reduced with the use of synthetic fibers. This allows for increasing the protective cover of concrete on steel, which is a major advantage towards increasing the service life of concrete in aggressive environments, including sanitary sewers, where microbial-induced corrosion is a major concern.