Anchorage Capacity of Headed Reinforced Bars in Concrete

Abstract

In reinforced cement concrete (RCC) structures, the bond between the concrete and the steel bar is critical. When the member geometry is insufficient for the full development of straight bars, headed bars can be used to anchor reinforcing steel due to the shorter development lengths and compact size, they can reduce congestion in the beam-column joints. Fiber- reinforced cementitious composites have been increasingly used in recent years on beam- column joints and the introduction of headed bars is a practical solution to eliminate the congestion problem caused by hooked bars in beam-column joints. The key in this study is the headed reinforced bar, which is used to anchor the steel in the concrete instead of straight or hooked bars. There has been very little research on the behavior of headed bars in RCC structures, especially when they are used with high-strength concrete. The ASTM A970 and ACI 318-19 codes are used to design and manufacture headed bars. The design provisions of ACI 318-19 limit the yield strength of headed bars to 413.68 MPa and concrete compressive strength to 41.6 MPa due to the limited research performed on headed bars to date. The main parameters in this study are concrete compressive strength, steel bar diameter, percentage of steel fibers, and head shape. The influence of head shapes (Square, Circular, and Rectangular), concrete compressive strength (M20, M40, and M60), the diameter of steel bar (16, 20, and 25 mm), and steel fibers (0, 0.5, 1, and 1.5%) on the anchorage capacity of headed bars have been evaluated.