Seismic Risk Assessment For Timber-structure Ancient Architecture

Our country is located in the areas which frequently occur natural disasters. Andour country whose cultural heritages are widely distributed has a long history. After the5.12Wenchuan Earthquake caused great losses of the cultural heritage in the disasterareas, people began to realize the situation of the disaster prevention and mitigation forthe cultural heritage is very serious. Based on the serious situations of the disasterbackground and the cultural heritage in recent years, the Bureau proposed the subject,"Risk assessment of the cultural heritage disaster and construction of disaster preventionsystem", in2009. The content of the research includes the timber-structure ancientarchitecture cultural heritage. The subject hopes to make out an earthquake disaster riskevaluation method which is suitable for our national conditions of timber-structureancient architecture, to provide the professional support for administrative departmentthe cultural relics to make macro-decision on the protection of the immovable objects oftimber-structure ancient architecture cultural heritage, and to accumulate the experienceof the system to the Risk assessment of China’s cultural heritage.Based on the predecessors’ research achievements, this paper puts forward aspecific method of earthquake risk assessment of the timber-structure ancientarchitecture. The earthquake risk assessment for timber-structure ancient architecturecontains the seismic risk analysis, the seismic vulnerability analysis, and the seismicdamage assessment of the timber-structure ancient architecture. This paper focuses onthe seismic vulnerability analysis of timber-structure ancient architecture. In this paper,the content is as follows:In the aspect of the seismic risk analysis, the probability distribution of the Seismicintensity obeys the Extremum Ⅲ type distribution. So this paper puts forward the seismic risk analysis model, in which the peak ground acceleration PGA is chosen as theseismic risk metrics IM.It can calculate out the mean annual exceeding probability ofthe peak ground acceleration. In the aspect of the seismic vulnerability analysis, thispaper uses a method, which is similar to the incremental dynamic analysis method, toget the structural earthquake response value, engineering demand parameter EDP, whenthe structure is inputted samples of random earthquake ground motion record. The EDPwill change with different IM. This paper simulates the relation for logarithmic normalcumulative distribution to get the seismic demand probability model. Consultingrelevant literature, this paper takes the interlayer displacement Angle to evaluate thetimber-structure ancient architecture’s damage level. According to the four criticaldamage condition of the timber-structure, this paper gets the structural abilityprobability analysis. On this basis, this paper establishes the earthquake vulnerabilitymodel of timber-structure, and the seismic vulnerability curve. Then, this papercalculates the conditional failure probability when the action of structure seismicdemand exceeds the corresponding seismic capacity under different ground motion.In the aspect of the seismic damage, this paper puts forward a simple earthquakedamage assessment method. On the basis of previous research, combined the seismicdamage with the seismic risk analysis, the seismic vulnerability analysis, this papercalculates the average risk value of the timber-structure. Established a rough risk ratingstandard used to divide the earthquake risk grade, we can judge the risk level of anytimber-structure, and this paper draws a map of probabilistic economic loss risk curvesto indicate the seismic risk.In order to prove the effectiveness of the method, using to assess the earthquakerisk of the timber-structure, this paper makes a seismic risk assessment of the famoustimber-structure buildings-Xi’an Bell Tower. Finally this paper calculates the averageannual seismic risk of the Xi’an Bell Tower, and points out that the risk level of theXi’an Bell Tower belongs to the medium risk.The results of this paper can provide the protection theory for the cultural heritageof the timber-structure ancient architecture.