SPLITTING DESIGN FOR ANCHORAGES AND SPLICES WITH POST-INSTALLED REINFORCEMENT

A detailed design concept for the anchorage length of reinforcement bars has been developed and confirmed by tests. The ultimate limit state (ULS) design for bond and splitting is derived from ACI 318, chapter 12. This approach allows taking into account the splitting bond strength of a given anchorage, i.e. the bond stress developed along the reinforcement at which the surrounding concrete will split. In fact, the resistance against pullout of a bar cast with the concrete is not necessarily the same as that of a bar set into a drilled hole by means of an adhesive mortar. However, the resistance against splitting of the surrounding concrete is expected to be the same in both cases. Thus the ULS design of the anchorage length takes into account the steel, concrete and bond strengths as well as the geometry of the anchorage or splice. Special attention has been given to the design provisions for splices. According to most of the current structural codes, the length required for an end anchorage has to be multiplied by a factor of 1.0 to 2.0. The approaches of ACI 318 and Eurocode 2 are compared and a specific design concept taking into account the available confinement around the splice is proposed. Several series of tests considering the concrete quality, the concrete cover, the transverse reinforcement and the type of anchorage (end anchorage, splice) have been performed to confirm the validity of the proposed design. More tests taken from the relevant literature have also been evaluated with respect to the splitting design concept. The proposed design concept allows an economical design especially of post installed anchorages and splices where costs arise not only from the amount of steel required, but also for drilling work and the adhesive mortar. 1