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Modern cities are prone to various natural and human-made hazards. To deal with these challenges, an effective risk analysis, reduction and management tool is required for all relevant threats. In recent years, a risk analysis and safety management system called the Multi-Hazards Shanghai (MH-SH) system was developed by the Shanghai Institute of Disaster Prevention and Relief to serve the policy makers of government in Shanghai for various disaster decision making of prevention and mitigation. The system can handle various disasters including earthquake, flood, typhoon and man-made fire that affect the operational security of Shanghai. In the paper, the general frame of the MH-SH system was briefly presented. Advanced methodologies and technologies were discussed for their capability of enhancing the platform in multi-disaster monitoring, detection, prediction and management. Finally, the way to the future development of the MH-SH system was concluded. LESS      Full article

Ensuring the safety of large curved-roof structures subjected to blizzards in cold regions remains challenging. This paper assesses the reliability of a large curved-roof structure considering the coupled effects of wind and snow. To this end, a two-way coupled simulation considering the interaction between snow particles and turbulent wind is first carried out using a computational fluid dynamics scheme and a spectral representation method based on the wavenumber-frequency joint power spectrum and stochastic harmonic function; thereby, the uneven snow distribution and stochastic wind field on a large curved roof are revealed. The probability density evolution method is then adopted to conduct a stochastic response and reliability analysis of the structure. The simulation results reveal that a credible uneven distribution of snow on the large curved roof can be obtained using the suggested snowdrift simulation scheme, and the refined spectral representation method can efficiently and accurately simulate the two-dimensional fluctuating wind field of the large curved-roof structure. It is shown that under stochastic wind, snow and self-weight loads for a 100-year return period, the large curved-roof structure has a higher risk of member yielding than of node deflection. Meanwhile, the axial stress acting on the structural member is far less than the maximum allowable stress and the structure is thus deemed to be sufficiently safe. LESS      Full article

The failure of urban street trees caused by strong winds and has several adverse effects on urban functions and public safety. This study developed a wind fragility model based on the mechanical analysis of urban street trees. The uncertainty of the important parameters involved in this model was quantified for species of interest. Specifically, the vine copula function was used to estimate the joint probability distribution of the geometric parameters. Furthermore, the tree fragility curves were obtained and then validated by the historical measured date. The proposed model may help in effectively identifying high-risk streets and regions. LESS      Full article

One major threat to cities at present is the increasing rainstorm waterlogging hazards due to climate change and accelerated urbanization. This paper explores the mechanism of rainstorm waterlogging and enables the fine simulation of surface water propagation over complex urban terrain. A novel community-scale waterlogging modeling scheme is presented by loosely coupling a one-dimensional sewer model with a two-dimensional overland model under an open-source framework. The coupled model was applied to Waigaoqiao Free Trade Zone located in Pudong New Area of Shanghai. To quantify the influence of rainfall intensity and drainage conditions on the waterlogging, 12 scenarios were constructed by combining four rainfall return periods (3, 5, 10, and 20 a) and three startup water depths (1.5, 2.0, and 2.5 m) of pump stations. The multi-scenario simulation results show that the waterlogging risk increases from north to south in the study area, and that risk zones with water depth above 0.3 m are mostly concentrated in the southwest and southeast corners of the site. The longer the rainfall return period, the larger the submerged area, and the spatial distribution of surface water accumulation is affected by local topography and drainage system. In addition, reducing the startup water depth of pump stations has an obvious effect on inhibiting the severity of water accumulation. The results provide insights into overland flow across an urban area with densely populated buildings and help to reduce the risk of rainstorm-induced waterlogging disasters. LESS      Full article

In many probabilistic analysis problems, the homogeneous/nonhomogeneous non-Gaussian field is represented as a mapped Gaussian field based on the Nataf translation system. We propose a new sample-based iterative procedure to estimate the underlying Gaussian correlation for homogeneous/nonhomogeneous non-Gaussian vector or field. The numerical procedure takes advantage that the range of feasible correlation coefficients for non-Gaussian random variables is bounded if the translation system is adopted. The estimated underlying Gaussian correlation is then employed for unconditional as well as conditional simulation of the non-Gaussian vector or field according to the theory of the translation process. We then present the steps for augmenting the simulated non-Gaussian field through the Karhunen-Loeve expansion for a refined discretized grid of the field. In addition, the steps to extend the procedure described in the previous section to the multi-dimensional field are highlighted. The application of the proposed algorithms is presented through numerical examples. LESS      Full article

No country will escape the ravages of climate change, but some, like small island developing states (SIDS), will be less able to withstand them. Their fundamental characteristics in essential domains pose existential threats for them. The paper borrows from Lukka and Vinnari’s work on domain and method theories as a lens to conceptually explore the question, “Is it possible for SIDS to become disaster resilient?” It turns out that SIDS might be too small, too isolated, too economically and institutionally weak, and too exposed to become disaster resilient. Their developmental state, economic, institutional, and community attributes are causes of significant vulnerabilities and undermine disaster resilience efforts. The challenges from climate change alone highlight the herculean task ahead for these small and tiny developing islands without transformative actions. The advantage for SIDS is their solid social system. Their populations are resourceful, and they can pivot if they need to. However, the lingering question remains whether that will be enough to mitigate the weaknesses in other critical resilience domains? LESS      Full article