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 minutes, and (iii) in residual state after exposure to standard ISO 834-1 fire of 90 minutes. 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.

本文介绍了一系列测试，以研究带有关键（设计欠佳）搭接接头的钢筋混凝土梁的火灾后（残余）性能。此外，针对实验结果验证了3D数值建模方法。研究了两种类型的梁，即具有连续钢筋的类型1和具有临界搭接的类型2。测试了每种光束类型的三个样本：（i）在环境条件下（参考测试），（ii）在暴露于标准ISO 834-1火60分钟后处于残留状态，以及（iii）在暴露于标准后处于残留状态ISO 834-1防火90分钟。在环境条件下，具有连续钢筋的梁由于产生拉力钢筋而失效，并导致了延性的载荷－位移曲线。另一方面，具有关键搭接接头的梁由于粘结分裂而失效，并导致脆性的载荷-位移行为。暴露于火中后，连续加固的梁对残余行为表现出名义上的火焰效应，而具有关键搭接接头的梁暴露于火中后，其能力急剧下降，性能下降。结果表明，选择的数值方法可以真实地再现实验。