The seismic risk, as the product of seismic hazard and vulnerability, is widely assessed based on the traditional inventory method with a detailed classified facilities and structures. The losses caused by historical earthquakes, show great variation in the same seismic intensity. Thus the study of uncertainty of building vulnerability is important to improve the accuracy of seismic risk assessment. Because of the complexity of the combined factors affecting the building vulnerability, it is hard to estimate the effects by using the simple models. The paper introduces Monte Carlo random testing method to simulate the seismic vulnerability and estimate its uncertainty in the case that complex affecting factors exist. By using the building damage data of 2008 Ms=8.0 Wenchuan earthquake in Sichuan, China, acquired through interpretation of post-earthquake RS images and field survey, the exemplary quantitative structural vulnerabilities are estimated. The results show that the vulnerability uncertainty with affecting factors can be accurately simulated.
