Assessment of the vulnerability of regional buildings considering low-temperature fields and seismic intensity measures

A large amount of field earthquake damage observation data indicates apparent anomalies in the seismic vulnerability of buildings in large regions under the influence of low-temperature fields and intensity measures. However, the impact of low-temperature fields has been considered less often, resulting in a lower quantification accuracy of the seismic risk model established for structural vulnerability in low-temperature zones. This paper innovatively considers the impact of low-temperature fields on large-scale regional buildings and improves upon the traditional structural seismic risk function. A report was made on the Mw 6.2 earthquake in Jishishan County, Gansu Province, China, on December 18, 2023, along with the structural failure status and seismic intensity data. The instrument and macroscopic intensity distributions were generated considering innovative intensity measurements and low-temperature fields. The historical average low-temperature data of ten cities and counties in Gansu Province, China, were collected and processed. A vulnerability assessment was conducted on the actual structural damage survey dataset (284,002 square meters of buildings) of three typical building portfolios taken during the Mw 6.1 earthquake in Minle County, Gansu Province, on October 25, 2003. One hundred fifty-one structural earthquake risk matrices considering the effects of low-temperature fields and intensity measures were established. Using nonlinear regression methods, three types of structural risk comparison curves were generated for the Minle earthquake (low-temperature field) and the Wenchuan earthquake (normal-temperature field). A structural fuzzy membership risk curve considering the effect of a low-temperature field was generated. A structural seismic risk index model considering a low-temperature field and intensity measures was developed by optimizing the traditional seismic vulnerability index function, and the rationality of the model was verified via empirical seismic loss data from the Minle earthquake. The analysis results indicate that the damage to adobe and wood (AW) building clusters under the influence of a low-temperature field is more severe than that to other building categories. Under the influence of temperature effects and intensity measures, earthquake damage to brick and concrete (BC) buildings is less severe than that to brick and timber (BT) buildings.