Comparison of bond stresses of deformed steel bars embedded in two different concrete mixes

Abstract

Catenary action in a precast concrete building structural system is one of the ways to avoid progressive collapse. The key for catenary action to work successfully depends on the strength performance of longitudinal ties, which closely depends on the bond performance between the ties and concrete. This paper investigates the effectiveness of deformed steel bar as catenary tie in precast concrete beam-column connection under column removal scenario. The main objective of the experimental work is to improve the bond performance between deformed steel bar and concrete topping. The parameter considered in the tests is the types of concrete for the topping. The different concrete mixes are normal concrete of Grade 40 and steel fiber reinforced concrete (SFRC). A series of pullout test specimens are conducted to investigate the bond behavior between the steel ties and the surrounding concrete. The results show the comparison of bond stresses of embedded deformed steel bars in two types of concrete mix. The deformed steel bar with concrete fiber provides higher bond strength as compared to bond in normal concrete. Therefore, it is more suitable for effective catenary tie in precast concrete beam-column connection for maximum efficiency and deformability in order to minimize progressive collapse.