This paper presents a numerical approach for predicting spalling in concrete structural members under fire conditions. The proposed approach evaluates spalling by taking into account the stresses generated due to pore pressure, thermal gradients, and structural loading under fire conditions. This approach is incorporated as a spalling sub-model into a macroscopic finite element based model that is capable of tracing the thermo-mechanical response of RC beams from pre-cracking stage to collapse under fire conditions. The analysis predictions, namely temperature, deflection, and extent of spalling are compared against the measured values from full-scale fire resistance tests on RC beams made with different concrete types of varying strengths. Results from the analysis indicate that pore pressure induced stresses are the primary trigger, though thermal and mechanical stress levels exert influence on the occurrence of spalling. Further, the level of spalling significantly influences fire resistance of concrete beams under severe fire exposures, and neglecting fire-induced spalling can lead to un-conservative fire resistance predictions in certain scenarios, specifically in the case of high strength concrete (HSC) and ultra-high performance concrete (UHPC) beams.

本文提出了一种数值方法来预测火灾条件下混凝土结构构件的剥落。所提出的方法通过考虑由于孔隙压力，热梯度和火灾条件下的结构载荷而产生的应力来评估剥落。该方法作为剥落子模型并入基于宏观有限元的模型中，该模型能够跟踪RC梁从预开裂阶段到火灾条件下坍塌的热力学响应。将分析预测（即温度，挠度和剥落程度）与使用不同强度的不同混凝土类型的RC梁进行的全面耐火测试的测量值进行比较。分析结果表明，孔隙压力引起的应力是主要触发因素，尽管热应力和机械应力会影响剥落的发生。此外，在严重的火灾暴露下，剥落的程度会显着影响混凝土梁的耐火性，而忽略火灾引起的剥落，可能会导致在某些情况下做出不保守的耐火性预测，特别是在高强度混凝土（HSC）和超高强度混凝土的情况下。 -高性能混凝土（UHPC）梁。