This study examined empirical correlations among several horizontal and vertical ground‐motion intensity measures (IMs), including spectral acceleration (SA), peak ground acceleration (PGA), peak ground velocity, acceleration spectrum intensity, velocity spectrum intensity, displacement spectrum intensity, spectrum intensity, effective peak acceleration (EPA), effective peak velocity (EPV), and effective peak displacement (EPD). The theoretical basis for the prediction equations of EPA, EPV, and EPD were developed based on the ground‐motion model (GMM) of SA(T). Horizontal and vertical Next Generation Attenuation (NGA)‐West2 GMMs and associated ground motions from active shallow crustal earthquakes in the NGA‐West2 database were used to calculate empirical correlations. Fisher ? transformation and nonparametric bootstrapping methods were able to accurately describe the uncertainty caused by the limited sample size. The multivariate normality of the total residuals of the horizontal and vertical ground‐motion IMs was verified. The results have shown a moderate correlation between the same IMs of horizontal and vertical ground motions. The difference in correlations between the IMs for two different combination cases (⁠ $IMi,H–IMj,V$ and $IMj,H–IMi,V$⁠) was not significant. The trends of $ρlnIMV,lnSAH$ and $ρlnIMH,lnSAV$ were almost the same, except that $ρlnIMV,lnSAH$ was greater than $ρlnIMH,lnSAV$ in the 0–0.3 s period, except for $ρlnPGAV,lnSAH$⁠. Moreover, the median correlation coefficients were parametrically fitted to establish a correlation coefficient prediction model. Finally, an example of constructing the conditional distribution using the correlation coefficient models for horizontal and vertical ground motions IMs was given. The correlation coefficient models by this study provide the theoretical basis for the selection of horizontal and vertical ground motions using generalized conditional intensity measure.

Since the approach of probabilistic seismic‐hazard analysis (PSHA) was proposed by Cornell (1968) and developed by McGuire (1976), the Cornell–McGuire method has been widely applied in many countries. However, the Cornell–McGuire seismic hazard assessment procedure cannot be directly used in China due to the spatially and temporally inhomogeneous nature of the seismicity of China. In addition, the commonly used PSHA procedure in China fails to provide the seismic hazard disaggregation (SHD) results that are needed in generating the conditional mean spectrum (CMS) for the specific building site of interest. To resolve this issue, theoretical characteristics of Chinese PSHA ($c‐PSHA$) are introduced and summarized in comparison with that for the Cornell–McGuire method. To facilitate the $c‐PSHA$ approach more efficiently and accurately, the procedures for conducting $c‐PSHA$ and SHD have been developed based on the Monte Carlo simulation (MCS) method. The proposed procedures are validated using the PSHA results based on the traditional numerical integral method. Using the developed $c‐PSHA$ and SHD results, both horizontal and vertical site‐specific uniform hazard spectra (UHS) and CMS can be generated as target spectra for selecting ground motions to conduct nonlinear time‐history dynamic analysis of structures in China. As a case study, the proposed procedures are used to perform PSHA and SHD for a nuclear power plant site in China, along with the generated site‐specific UHS and CMS.

The reinforced concrete (RC) piers of offshore bridges inevitably experience seawater freeze–thaw cycles due to the periodic movement of tides in cold climates. The damage caused by seawater freeze–thaw cycles will reduce the durability and mechanical properties of concrete, and then affect the seismic performance of RC piers. The method of seismic performance analysis on RC piers by numerical simulation is gradually emerging because the process of the conventional experiment is relatively complicated, and the heterogeneity and degradation of concrete after seawater freeze–thaw cycles should be considered. In this study, the method of meso-element equivalent and layered modeling was used to simulate a low cyclic loading test on an RC pier after seawater freeze–thaw cycles with ABAQUS software. The numerical simulation results were compared with the experimental results; the deviation value of peak load was not more than 6%, and the deviation value of peak displacement was not more than 10%. The result of the numerical simulation matched well with the experimental results, and the influence of different parameters was analyzed through the practical method of numerical simulation. It can be determined that the peak load decreased by 11%, while the peak displacement increased by 40% after 125 seawater freeze–thaw cycles. In the same 125 freeze–thaw cycles, the peak load increased by 15% and 27% while the axial compression ratio and the longitudinal reinforcement diameter increased. As the stirrup spacing of specimens decreased, the peak load remained unchanged, but the ductility coefficient of the specimens increased by 20%.

Precast segmental reinforced concrete (RC) piers have been widely used in the construction of offshore bridges to speed up construction. Offshore bridges in cold regions are inevitably affected by the seawater freeze–thaw cycles under the periodic movement of tides, which could reduce the mechanical property of RC piers. Based on the low cyclic loading test on 12 specimens with different seawater freeze–thaw cycles, axial compression ratio, diameters of longitudinal reinforcement, and stirrup spacing, the hysteresis characteristics of precast segmental RC piers were analyzed. The test results show that the peak load decreased by 11%, while the peak displacement increased by 40% after 125 seawater freeze–thaw cycles. The hysteresis curves became fuller and the residual displacement became smaller with the accumulation of freeze–thaw damage. In the same 125 freeze–thaw cycles, the peak load increased by 15% and 27% while increasing the axial compression ratio and the longitudinal reinforcement diameter. Combined with the regression analysis of the experimental results, the restoring force model of RC piers considering the seawater freeze–thaw damage and design parameters was established, and the calculation method of each characteristic point in the model was given. The deviation values of flexural capacity are not more than 6.5%, and the deviation values of peak displacement are not more than 12%. The restoring force model determined in this paper could provide a reference for seismic response analysis of offshore bridges in cold regions.