CCEER-22-02: Response And Behavior Of Mechanical Connectors For Application In Rebar Cages: An Experimental Study

Abstract

Collapse of rebar cages often leads to construction schedule delays, added costs, and sometimes injuries and fatalities. These cages are commonly used for the construction of reinforced concrete structures. They consist of longitudinal and transverse reinforcing bars connected by tie-wires. Analytical and experimental investigations showed that the lateral strength and stability of these cages depend on the tie wire connections. The experimental testing of tie wire connections showed they are weak and flexible, thus causing the poor lateral strength and stiffness of rebar cages. Mechanical connectors, such as U-bolt or clamps, can replace tie-wire connections by joining the longitudinal and transverse rebar. These connectors can be used at selected locations along the cage to improve the cage strength and stability.

This report presents the results of experimental tests conducted on various types of mechanical connectors to determine their force-deformation response for different degrees of freedom. The tests utilized ribbed and plain rebars with various sizes of transverse bars. The force-deformation responses were idealized with bilinear models to be used in computational models to investigate the system-level behavior of rebar cages. Test results showed that the mechanical connectors are twenty times stronger and provide larger stiffness when compared to tie wire connections. This significant increase in strength and stiffness shows great potential in using mechanical connectors to improve the lateral stability of rebar cages.