A COMPARISON OF THE ANCHORAGE PERFORMANCES OF PRE-CAST AND POST-INSTALLED REINFORCEMENT IN CONCRETE MEMBERS SUBJECTED TO FIRE EXPOSURE

Although it is generally assumed that a decay in bond performance of reinforcement bars in concrete due to exposure to high temperatures exists, the evaluation of its effects on the anchorage of longitudinal reinforcement in beams or slabs subjected to fire still under discussion. Additionally, in recent years the use of adhesive mortars significantly increased. While at ambient temperature higher bond values compared to cast in rebars are usually detected, at elevated temperatures the concrete-adhesive bond tends to significantly weaken with a significant product type dependence as for the decay of bond strength. Initially, the effects of elevated temperatures on the bond strength of both pre-cast and post-installed rebars are discussed. Successively, an evaluation of the effects of fire exposure on the anchorage and lap splices is presented. Results are presented as a function of fire duration and rebar position, also with respect to existing code provision discussing the difference between pre-cast or post installed rebars