Experimental and numerical investigations on the residual bond capacity of RC flexural members exposed to fire considering twin rebars

Exposure to fire can deteriorate steel-to-concrete bond, which is essential for structural integrity of reinforced concrete members. Prediction of the performance under fire is essential for design, while estimating the post-fire bond is paramount for assessing damaged structures. Existing research focused on the performance of a single rebar. Study reported herein deals with experimental and numerical investigation of post-fire bond behaviour of members with twin rebars. Experimental results are used to validate the numerical approach, which is subsequently used to extend the experimentally tested range of fire duration. Severe impact of fire on bond is observed, regardless of the concrete cover, rebar spacing and fire duration. A reduction in bond capacity is observed for twin rebars compared to single rebar for all the investigated cases. • Experimental and numerical investigation of post-fire bond behaviour of reinforcement in concrete. • The bond performance of twin rebars is investigated and subsequently compared to existing results on single rebar. • Different concrete cover and spacing between rebars are considered. • Bond performance is investigated employing beam-end specimen subjected to ISO 834 fire. • The disparity in bond capacity between the single and twin rebars observed under ambient conditions as well as for all the fire exposure durations.