Journal of Earthquake and Tsunami

In this paper, a stochastic dynamic analysis method for cable-stayed bridges subjected to multi-dimensional and multi-supported earthquake and waves is established based on the pseudo-excitation method. The Monte Carlo method is used to analyze the influence of excitation nonlinearity on the bridge structure response, and the applicability of this method is verified. Stochastic response characteristic of coastal cable-stayed bridges subjected to multi-dimensional and multi-supported earthquake and waves is studied. The influence of water–structure interaction on the stochastic seismic response of main components of the cable-stayed bridge is described, and the influence of key parameters is analyzed. The results show that the influence of excitation nonlinearity on the response of the cable-stayed bridge can be neglected. A greater energy input caused by the rigid additional mass of the hydrodynamic pressure is the reason for the increasing of the seismic response. The influence of stochastic response of the underwater structure of the tower is changed with the site conditions. For the ground motion acceleration input energy being distributed in the high-frequency domain, the water–structure interaction has a greater effect on stochastic seismic response of the underwater structure of the tower. The influence of water–structure interaction on the stochastic seismic response of the underwater structure of the cable-stayed bridge increases with the increasing of the wave height and water depth.

To reduce the damage caused when a tsunami overflows coastal dikes, this study performs hydraulic experiments and numerical simulations and proposes a new method for slowing the tsunami by intentionally eroding parts of the ground. The effectiveness of the proposed method is assessed, velocity-reduction mechanism is clarified, and reduced tsunami velocity is predicted. Using crushed expanded polystyrene (EPS) as the ground material, vertical erosion is enhanced and a large depression is formed that changes the flow from supercritical to subcritical, thereby decelerating it. Assuming a constant tsunami overflow rate, the tsunami velocity after deceleration can be predicted with $\sim 20\%$ uncertainty.

In both seismic design and probabilistic seismic-hazard analyses, site effects are typically characterized as the ratio of the response spectral ordinate on the ground surface to that on the bedrock based on the scaling law borrowed from the Fourier spectral ordinate. Recent studies have shown that different from the Fourier spectral ratio (FSR), the response spectral ratio (RSR) does not purely reflect the site effects but also depends on the earthquake scenario even for linear analysis. However, previous studies are limited to theoretical analysis. This study statistically compares the two spectral ratios by analyzing many actual seismic ground motions recorded at nearby soil and rock sites. It is observed that the average RSR and FSR have similar overall shapes, and their maximum values occur at approximately the same period; however, the values around the peak are clearly different with FSRs consistently exceeding the RSRs. The RSR–FSR relationship depends on the earthquake scenario and the oscillator damping; their difference at periods longer than the site’s fundamental period decreases as the magnitude and epicentral distance increase, and the RSRs generally approach the FSRs as the oscillator damping decreases.

An earthquake is one of the most serious natural disasters to human beings. The damage from destructive earthquakes is enormous, and the predictions and estimations of earthquakes are urgent challenges in global science fields. In view of the shortcomings of the Markov chain model and the kriging methods in the estimation of the probabilities of the occurrence of earthquakes, the Markov chain–linear kriging coupling model has been established. The model has been applied to estimate the spatial distribution of probabilities of the occurrence of destructive earthquakes of Ms4.5 and Ms6.0 and above in the Sichuan area. According to the estimations of this model, the maximum probabilities of the occurrence of earthquakes of Ms4.5 and Ms6.0 and above in the Changning area of Yibin are 9.59% and 0.46%, respectively, which are close to the frequencies of occurrences of earthquakes of corresponding magnitude in the series of earthquakes that occurred in June 2019 in the region. The validation indicates that the average standard errors of this model for estimating the probabilities of the occurrence of earthquakes of Ms4.5 and Ms6.0 and above are 4.96% and 0.81%, respectively, which are lower than the probability kriging, and the estimation of this model highlighted the high value region of the probabilities.

Several studies on liquefaction using physical model tests and numerical analysis have been conducted in recent years; however, few studies have investigated the effect of liquefaction-induced settlement on structures. Especially, this settlement seriously influences on gravity foundation during earthquake. This study aims to investigate the settlement of the surrounding ground of steel pipe sheet pile (SPSP) foundation during liquefaction by using an effective stress analysis. 2D numerical modeling was used in this study and the behavior of undrained soil was idealized using a cocktail glass model. The numerical results were compared with experimental results from a 1-G shaking table test with a scale of 1:60. The results indicate that the settlement of surface ground and SPSP foundation rapidly increase when the liquefaction occurs and is significantly influenced by permeability coefficient of ground.