To study the freeze-thaw damage characteristics of concrete, the uniaxial compressive tests of concrete under different number of freeze-thaw cycles were conducted, and the damage variable of freeze-thaw was obtained. The test results showed that the stress was a function of strain and freeze-thaw damage variable, and it can describe the degradation of concrete strength. Meanwhile, the equation for the stress-strain curved surface about strain and freeze-thaw damage variable was also proposed in this paper. The derivative function of the stress-strain curved surface equation with respect to strain presented the change of elastic modulus with the increase of freeze-thaw cycle number. Equation proposed in this paper can be used for predicting the concrete lifetime effectively in cold and large temperature difference regions.

The analysis of the mechanical behaviour of reinforced concrete slabs on elastic foundation under impact loads is of great significance in the construction and protection of concrete pavements in airports. Based on the Elastic Half-space Foundation Model and Concrete Damage Plasticity Model, the displacement and stress fields of reinforced concrete slabs under impact loading are numerically simulated by explicit nonlinear finite element method. The result can be used to design and evaluate the safety of foundations and reinforced concrete slabs under impact loads.

To analyze the causes of failure of cubic concrete test specimens under quasistatic axial compression, microtests and finite element numerical simulation of C40 cubic concrete test specimens were conducted without the freeze‐thaw cycle and with 50 freeze‐thaw cycles. Based on the analysis of the microstructure of concrete, the variation law of the full curve of stress and strain was analyzed by the uniaxial compression test and the splitting tensile test of concrete. The results show that freeze‐thaw damage is mainly caused by the cyclic reciprocating stress of the micropore structure inside the concrete. The peak stress of concrete uniaxial compression and splitting tensile strength gradually decrease with the number of freeze‐thaw cycles; the full stress‐strain curve tends to shift downward and to the right. Finite element analysis shows that under the quasistatic uniaxial compression loading condition, the stress and strain fields in the test specimens are symmetrically distributed but nonuniform. The plastic deformation of the concrete weakens the nonuniformity of the stress distribution and is closer to the experimental failure morphology.