Post-fire performance of RC beams with critical lap splices – Experimental investigation and numerical validation

This paper presents a series of tests conducted to study the post-fire (residual) performance of reinforced concrete beams with critical (under-designed) lap splices. Furthermore, a 3D numerical modelling approach is validated against the experimental results. Two types of beams, namely Type 1 - with continuous reinforcement, and Type 2 – with critical lap splice, were investigated. Three specimens of each beam type were tested: (i) in ambient conditions (reference tests), (ii) in residual state after exposure to standard ISO 834-1 fire of 60 min, and (iii) in residual state after exposure to standard ISO 834-1 fire of 90 min. Under ambient conditions, the beam with continuous reinforcement failed due to yielding of tension reinforcement and resulted in a ductile load-displacement curve. On the other hand, the beam with critical lap splice failed due to bond splitting and resulted in a brittle load-displacement behaviour. After exposure to fire, beams with continuous reinforcement showed a nominal effect of fire on residual behaviour, while the beams with critical lap splice displayed a drastic reduction in their capacity and poor performance after exposure to fire. It is shown that the chosen numerical approach realistically reproduces the experiments. •Tests for residual performance of beams without and with lap splice after fire.•Performance of beams with continuous reinforcement only marginally affected by fire.•Performance of beams with lap splice strongly affected by fire.•Bond splitting failure of lap splice leads to brittle beam failure.