Abstract: In order to explore the variation of the splitting tensile strength of concrete after high temperature, 156 pieces of C30 and C40 concrete blocks with the size of 100 mm×100 mm×100 mm were made by choosing the mix ratio of concrete commonly used in this area. The simulated fire tests were carried out under different conditions of 60 min and 90 min fire time, natural cooling and water spraying cooling, 1d and 14d standing after high temperature. The splitting tensile strength values of concrete specimens with different fire time, cooling methods, standing time and strength grade after high temperature were obtained. The influence degree of different working conditions was further analyzed, which provides the basis for the appraisal and reinforcement design of building structures or components after high temperature.

Key words: high temperature, concrete strength, fire time, standing time, cooling method, splitting tensile strength