Seismic Performance Assessment Of Urban Bridge Network Considering The Post-disaster Evacuation Capacity

Highway bridge network is not only an important component of the lifeline systems in urban city, but also plays a critical role in maintaining the daily working life, emergency response and evacuation, even the social economy restoration and reconstruction after a disastrous earthquake. As key parts of bridge network, bridges are vulnerable to seismic-induced damages and the seismic performance of bridges determines the traffic capacity of the highways. The research of seismic performance of highway bridge network is of great significance to the development of the theory of earthquake engineering.On the basis of the importance analysis of bridge networks in the phase of earthquake rescue and evacuation, this paper presents a methodology to investigate the seismic performance of highway bridge networks holistically and systematically. The influence of the bridges’ seismic vulnerability to the whole network is evaluated. The main research content is summarized as follows:(1). The seismic evaluation concept based on the capacity importance of urban highway bridge network system is discussed firstly. With the analysis of the importance of individual bridges in the pre-earthauake bridge networks, and the functional loss effects in post-earthquake of the bridge network, analysis framework and concept of the seismic performance assessment for bridge network is proposed.(2). Based on the concept of the unit importance of the bridge networks, the indices influencing the importance of bridges in networks and the corresponding weighting factors are analyzed. The importance analysis model is set up and programmed with the help of matlab to analyze the importance of bridges in bridge networks.(3). The functionality calculation of the bridge networks in post-earthquake is illustrated systematically. With the help of the software Hazus, the seismic vulnerability of individual bridges is analyzed to achieve the post-earthquake traffic capacity factors. Based on the integration of the analysis of the seismic performance and importance of the individual bridges, the performance of the bridge networks is programmed in matlab.(4). An example bridge network is analyzed to testify that the methodology presented is effective. The analysis result indicates that the change of the capacity of the bridge network considering the importance of is different with the variation of the total mileage. With the increasement of magnitudes, the traffic capacity of the bridge network suffers less than the total mileage, however, the trend is the same.