The paper innovatively studies the impact of dual randomness of structural parameters and seismic excitation on the seismic reliability of highway pile–slab structures using the probability density evolution method. A nonlinear stochastic dynamic model was established through the platform, integrating, for the first time, the randomness of concrete material properties and seismic motion variability. The main findings include the following: Under deterministic seismic input, the displacement angle fluctuation range caused by structural parameter randomness is ±3%, and reliability decreases from 100% to 65.26%. For seismic excitation randomness, compared to structural parameter randomness, reliability at the 3.3% threshold decreases by 7.99%, reaching 92.01%. Dual randomness amplifies the variability of structural response, reducing reliability to 86.38% and 62%, with a maximum difference of 20.5% compared to single-factor scenarios. Compared to the Monte Carlo method, probability density evolution shows significant advantages in computational accuracy and efficiency for large-scale systems, revealing enhanced discreteness and irregularity under combined randomness. This study emphasizes the necessity of addressing dual randomness in seismic design, advancing probabilistic seismic assessment methods for complex engineering systems, thereby aiding the design phase in enhancing facility safety and providing scientific basis for improved design specifications.

In this paper, an experimental study of steel fiber concrete using vibration mixing technology and the probability density evolution theory is applied to establish a nonlinear stochastic seismic response model for multistory concrete frame structures considering the randomness of structural parameters. The random evolution characteristics of the structural response are studied and analyzed, and a reliability analysis method for concrete frame structures based on PDEM theory is proposed. The equations are solved by the finite difference method in the TVD format, and the probability distribution of the deformation index of the concrete frame structure is obtained by summation, where the reliability is given according to the limit value of the index. The results confirm that the PDEM theory can accurately assess the functional reliability of the structure, and it is also found that the randomness of the structural parameters has a significant effect on its nonlinear dynamic response law, and that consideration of the randomness of the structural parameters at the early stage of the design can be of great help to the seismic resistance of the structure. This study not only provides a scientific basis for the optimization of the performance of steel fiber concrete but also provides a new perspective and tool for the analysis of probability density evolution in the field of structural earthquake engineering.