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The energy content of ground motion records obtained during the 2019 M6.4, M7.1 Ridgecrest, California earthquakes which occurred closely in space is analyzed in this paper. Wavelet transform as a powerful tool, that is used to evaluate the energy content characteristics including cumulative energy profiles and the total energy for different components of records, was obtained at three stations named China Lake Christmas Canyon, China Lake and Tower 2. Due to the fact that the energy-based parameters could be well correlated with damage distribution, this path has been taken into consideration in this research work with the light of the powerful wavelet tool. For this purpose, the discrete wavelet transform is efficiently used for multi-resolution decomposition of acceleration time history of ground motions and a new framework is presented to estimate the energy level of earthquake sequences. Finally, the pseudo-period corresponding to each corresponding level is introduced and the distribution of energy vs. the pseudo-period is discussed. The results of this paper provide a platform to compare the energy levels of different earthquake sequences in different periods. Analysis showed that wide-band energy distribution could be identified at China Lake Christmas Canyon and Tower 2 stations. [ABSTRACT FROM AUTHOR]

The new generation of China Railway Track System III (CRTS III) ballastless track structure has been found vulnerable under high-level earthquakes. However, the seismic characteristics and the damage mechanism had not been well studied. In this paper, a 4-span high-speed railway (HSR) simply supported bridge-track system model is established to investigate the seismic response and damage mechanism of the bridge-CRTS III slab ballastless track system under transverse earthquakes by nonlinear history analysis. In accordance with the results, the piers have a good seismic performance under high-level earthquake (0.57 g). The non-uniform vibration of unequal-height piers results millimeter-level inconsistent displacements between the girders. The fixed bearing is vulnerable under the earthquakes with PGA of 0.3 g and 0.57 g, indicating that the seismic design of fixed bearing should be optimized to enhance the seismic resistance under high-intensity earthquake. After the damage of fixed bearing, the friction is not enough to pull the girders to vibrate together with piers which leads the sliding of girders. The sliding of girder exacerbates the non-uniform displacements of girders and roadbed. The non-uniform vibration and residual slips of girders lead deformation of the rail, especially forming turning angles at the girder joints which may impact the safety of train operation. [ABSTRACT FROM AUTHOR]

Railway transportation, as an important lifeline during earthquake relief and post-disaster reconstruction, has an extremely significant role. The study of track irregularity caused by earthquakes is the basis for ensuring traffic safety after their occurrence. In this paper, a finite element model of a five-span simply supported high-speed railway beam bridge with the China Railway Track System (CRTS) II was established and an experimental verification was performed. Eighty arbitrarily selected seismic waves were extracted from the Pacific Earthquake Engineering Research Center (PEER) strong ground motion database and a nonlinear time-history analysis was performed on the finite element model. The frequency–domain distribution law of earthquake-induced track irregularities was studied. A stable target earthquake-induced track irregularity spectrum model was constructed, and its expression was fitted. According to the results, in the case of transverse earthquakes, the rails experienced noticeable alignment irregularity and cross-level irregularity, while the amplitude of the gauge and vertical irregularity were relatively small. The target irregularity spectrum has a higher amplitude in the low-frequency components. When peak ground acceleration (PGA) was low, earthquake-induced track irregularity was not obvious, but the deteriorating effects of earthquakes on track irregularities increased significantly with increasing PGA. [ABSTRACT FROM AUTHOR]

Community is directly responsible for implementing the policy measures against public emergencies such as extreme weather, earthquake, flash flood and pandemic diseases. Summarizing the experience at the urban community level can help promote the global emergency management. This paper, from the perspective of COVID-19 prevention and control, selects three communities with different features to explore an effective response system for public emergency management at the urban community level. It demonstrates that based on a centralized leadership, the multi-level governance (MLG) network combined with information technology has mobilized their participation in combating COVID-19 and ensured the effective and timely response to the public emergencies, which blocked the spread of epidemic to the greatest extent, proving worthy of being promoted as one of the Chinese approaches and Chinese wisdom. [ABSTRACT FROM AUTHOR]

Numerous earthquakes occur throughout the world, and thus, earthquake emergency plan is a significant issue that concerns everyone in the affected areas. However, the absence of an effective, scientific assessments system may lead to a lack of awareness about the effectiveness and comprehensiveness of earthquake emergency plan implementation. This delays the construction of emergency plan and leads to low operational efficiency. In order to improve this situation, this paper aims to efficiently assess the earthquake emergency plan implementation to accelerate the replenishment and the amendment of the earthquake emergency plan. Firstly, we review the existing researches on the earthquake emergency system and some guidelines and plans of earthquake emergency. Secondly, we carefully conduct 30 indicators to assess the effectiveness of earthquake emergency plan implementation in terms of operational mechanism, emergency response, and emergency safeguards. Thirdly, according to the characteristic information obtained from the effectiveness assessments of earthquake emergency plan implementation, and based on the advantages of hesitant fuzzy elements for expressing information, we develop a method for the effectiveness assessments of earthquake emergency plan implementation using hesitant analytic hierarchy process (HAHP). Furthermore, we apply the method to assess the Wenchuan, Yushu and Lushan earthquakes, and also compare our method with the analytic hierarchy process. Based on our analysis, we conclude that the HAHP is highly suitable for assessments of earthquake emergency plan implementation's effectiveness. [ABSTRACT FROM AUTHOR]

Current structural design codes usually treat multiple hazards separately, and probabilistic backbones are rare for extreme hazard combinations, e.g., earthquake and strong wind, which may cause unforeseen damage to engineering structures exposed to multiple extreme hazards during their lifecycles. This study presents an innovative copula-based approach to construct the joint cumulative distribution function (JCDF) of the peak ground acceleration (PGA) and strong wind speed (V). Six commonly used Archimedean copulas are applied to bond the JCDF with the corresponding marginal cumulative distribution functions (MCDFs) of PGA and V. A total of 76 low-probability-high-consequence extreme events with a simultaneously occurring earthquake and strong wind are abstracted from data recorded from 1971–2017 in Dali Prefecture, China. The statistical analysis results show that the Frechet and truncated Weibull distributions are the optimal expressions for the marginal distributions of PGA and V , respectively, while the Joe Archimedean copula can yield good JCDF estimation. Monte Carlo simulation is employed to establish a target dependent multihazard database that can be used for the performance-based design of engineering structures against multiple natural hazards. A high-rise building is used to study the performance under the multihazard of an earthquake and strong wind. The results show that the maximum inter-story drift ratio of the building under multiple hazards increases by 14.4–21.3% compared with the structural response induced by an earthquake alone. [ABSTRACT FROM AUTHOR]