Modeling the Fire Response of Reactive Powder Concrete Columns with Due Consideration of Transient Thermal Strain

Transient thermal strain (TS) is a unique compressive strain that reactive powder concrete (RPC) experiences during temperature rise. RPC has a more rapid TS development than normal concrete (NC) during temperatures of 300 °C~800 °C, and under the same load level, the TS of RPC is 40% to 60% higher than that of NC. However, while TS is known to be significant in RPC, its quantitative influence on the structural fire response and ultimate fire resistance of RPC columns remains insufficiently understood and inadequately modeled, posing a potential risk to fire safety design. In this study, a method for modelling the fire response of RPC columns with due consideration to TS was developed using ABAQUS. The Drucker–Prager model was applied to assess the impact of TS on the fire resistance of RPC columns. The results indicate that ignoring the effect of TS could lead to unsafe fire resistance predictions for RPC columns. The influence of TS on the fire resistance performance of RPC columns increases with the increase in cross-sectional dimensions. When the cross-sectional dimension of RPC columns increases from 305 mm to 500 mm, the influence of TS on the fire resistance of RPC columns increases from 22% to 43%. Under the same load, the influence of TS on the fire resistance of RPC columns is 31.3%, which is greater than that on NC columns. When the hydrocarbon heating curve is used, if the influence of TS is not considered, the fire resistance will be overestimated by 18.2% and 37.7%. Under fire, the existence of TS will lead to a further increase in the compressive stress of the RPC element in the relatively low temperature region, resulting in a greater stress redistribution, and accelerating the RPC column to reach the fire resistance. Therefore, it is crucial to clearly consider TS for the accurate fire resistance prediction and safe fire protection design of RPC columns. Crucially, these findings have direct significance for the fire protection design of actual projects, such as liquefied petroleum stations.