In performance-based seismic design theory, the accurate selection of ground motion intensity parameters is crucial for the probabilistic assessment of structural seismic performance. To achieve efficient, sufficient, applicable, and complete prediction of structural seismic demands, this study systematically evaluates the comprehensive performance of 35 commonly used ground motion intensity measures (IMs). The research begins by analyzing 178 real records from the Pacific Earthquake Engineering Research Center (PEER) database, employing the Spearman rank correlation to reveal intrinsic relationships among the parameters. Subsequently, a ground motion database classified according to four site types based on Chinese seismic design codes is established. Combined with seven single-degree-of-freedom (SDOF) structural models of different periods, the performance of the IMs is comprehensively evaluated from four dimensions: correlation, efficiency, applicability, and completeness. Finally, by comparing the evaluation results under both bilinear and Clough stiffness-degrading bilinear hysteretic models, the robustness of the parameter selection is verified. The results demonstrate that: acceleration-related parameters are most suitable for short-period structures, velocity-related parameters for medium-period structures, and displacement-related parameters for long-period structures. Parameters Sv_avg and Sd_avg exhibit consistent performance across all period ranges and under different site conditions, and the evaluation results remain consistent across different hysteretic models. This study provides a systematic basis for the rational selection of intensity parameters in probabilistic seismic demand analysis, significantly enhancing the reliability and precision of seismic performance assessment.

The current engineering structural design code employs a direct probability design method based on the Taylor series expansion of the performance function at verification points, retaining only linear terms. This approach ignores the curvature and other nonlinear properties of the performance function, leading to insufficient accuracy. To address the deficiencies of the current design method, this paper develops an approximate probability design method that considers the curvature of the limit state surface, integrating it with the second-order moment theory based on the direct probability design method. Using a simply supported plate as a representative example, this paper systematically compares the performance of the proposed design method with the direct probability design method, the partial coefficient method, and the design value method in reinforcement design. The reinforcement areas calculated by the four methods are similar, confirming the correctness and practicality of the proposed method for engineering applications. The accuracy of the design outcomes from the various methods is validated through Monte Carlo simulation. The results indicate that the method proposed in this paper exhibits a high accuracy, with the relative errors of the reliability indices in the two examples being 0.346% and 0.228%, respectively—significantly lower than those of the direct probability design method (2.919% and 0.769%, respectively). This underscores the effectiveness and substantial benefits of the proposed method in structural reliability design, offering a dependable, highly accurate, and economically viable design tool for engineering applications.

To solve the construction safety problem of ultra-buried and large-span rich water tunnels, and in combination with the entity project of the Manchuanguan ultra-buried and large-span rich water tunnel, a construction safety analysis of ultra-buried and large-span rich water tunnels is carried out using FLAC3D software. The construction method and safety measures for the shallow buried underground excavation rich water tunnel are put forward, which can solve such key problems as construction method, drainage, drilling and blasting of the ultra-shallow buried underground excavation large-span rich water tunnel. The on-site monitoring results show that the construction methods and safety measures adopted are feasible, and have important engineering application value.