Measuring the Structural Vulnerability of Road Network:A Network Effciency Perspective

The purpose of this paper is to identify the critical road sections and intersections in a road network which have great influence on the normal transport functions of the road network and to optimize the road network structure by reducing its vulnerability. In this paper, the framework of road network structural vulnerability measurement and improvement model is proposed. The network efficiency model is used to define road network structural vulnerability. Shanghai freeway network is analyzed based on this model. We find that using this model the critical components of the road network can be identified. Two methods which are increasing connections and rewiring are proposed to optimize the road network structural vulnerability and the results can be used to reduce the network vulnerability. The measurement method that we put forward for structure vulnerability is useful and important to optimize road network structure.

Coupling effect analysis of dam break flood spread and building collapse based on numerical simulation

Large-scale floods induced by dam failures could cause significant structural damage to buildings and massive loss of life.The coupling effect of large-scale flood spread and building collapse has complex impacts on the entire flow field,affecting flood risk assessment and building vulnerability evaluation.In this paper,a dynamic elevation change model designed to seamlessly interface with a structural vulnerability assessment model to investigate the interaction effect between floods and buildings is presented.The efficiency of the framework was validated by reconstructing the Gleno Dam-Break flood in Italy.Subsequently,a hydrodynamic model of the Jinsha-Yalong River that considers dynamic building collapse was established.The proposed model was compared with two traditional building treatment approaches and one that ignored the buildings.The results show that the interaction between the flood and buildings decreases the low-velocity area(below 1 m/s)by 7.44%-9.56%while increasing the high velocity area(above 4 m/s)by 10.71%-11.96%.Traditional and neglecting building treatments provide preliminary insights into densely built areas,and the latter could be an alternative for simplification because it can represent the worst-case scenario.Building collapse in response to large-scale floods typically occurs in four stages:flood spread,rapid expansion,gradual expansion,and flood recession.This analysis offers novel perspectives on flood prediction and simulations where the floodplain may contain buildings.This method could be useful for assessing structural vulnerability associated with large building stocks and developing flood mitigation strategies in densely populated areas.

Estimation of rural housing structure and its vulnerability in China

The damage of dwelling houses constitutes the primary cause of casualties and asset loss in seismic disasters that occurred in Chinese rural areas. The structure of houses is crucial for assessing the vulnerability of rural houses. However, at present, available data on rural housing structure are incomplete and their spatial scales are inconsistent. This paper estimated the amount and ratio of rural houses in five structures, namely ＇wood＇, ＇brick＇, ＇mixed＇, ＇reinforced concrete＇, and ＇other＇, for 2380 counties across China. With the percent- age sampling census data in 2005, four accuracy levels were specified. Then, a set of down-scaling models were established, where the impact of climate, economic development level and ethnic minority cultural factors on rural housing structure, as well as the spatial autocorrelation of neighboring spatial units were considered. Based on the estimation results, a database of county-level rural housing structure was established, based on which the vul- nerability of rural houses in different areas was clarified.