Study Of Fuzzy Comprehensive Evaluation Of Bridge Damages In Wenchuan Earthquake

In recent years, the world entered a period of high frequency of earthquake happening. The earthquakes occurred in most countries have caused heavy casualties and economic losses. Traffic facilities are seriously damaged in the earthquakes, especially to the bridge structures. The destruction of bridges in earthquake is a serious impediment to the relief work after the disaster, thereby causing more damages. In the past, bridge seismic standards are comparatively low, most of our bridges have been built in low seismic capacity. These studies, which are basic works in an earthquake, can provide theory references for post-disaster reconstruction and reinforcement work."5.12" Wenchuan earthquake destroyed a large number of transport lifelines. The economic losses of transportation facilities amounted to 67 billion Yuan, in which the bridge damage is the most serious. Under this background, some significant damages on the part of the bridge circuit are investigated and studied in this paper. Based on the investigation, the method of post-earthquake bridge evaluation is researched and the method of bridge fuzzy-vulnerability is proposed.Through the analysis of damaged bridge in Wenchuan earthquake, the problems in bridge seismic design and seismic performance are clearly reflected. This paper mainly describes the methods of fuzzy theory and multi-level fuzzy comprehensive evaluation method, in which the characteristics of seismic data are taken in to account. Based on fuzzy mathematics, the assessment model of damaged bridge in Wenchuan earthquake is built through multi-level fuzzy comprehensive evaluation method and the Matlab program is developed. On the basis of the fuzzy comprehensive evaluation, the method for calculating the cost of repairing the bridge after the earthquake is proposed, which is considered from the direct and indirect losses.An introduction of bridge seismic vulnerability theory is made from the view of traditional experience method and theoretical calculation method, and the advantadges and diadvantage of traditional method are summarized. Based on fuzzy comprehensive evaluation method, fuzzy probability and probability-possibility distribution theory, the method of the seismic fuzzy vulnerability analysis of simply supported girder bridge is proposed. The collected bridge damage data is analyzed through fuzzy comprehensive evaluation theory, respectively. Then statistical analysis of the evaluated results by classification of pier; the number of bridge span, the bridge main span and the basic seismic intensity of bridge site the four sides to get the fuzzy bridge fragility curves. The two-dimensional uncertainty caused by the uncertainty of bridge damage evaluation and the small amount of sample data is considered in fuzzy vulnerability theory, which is a very clear and worthy to be promoted bridge seismic vulnerability analysis method.