# A Story-Based Random Structure Modeling Method for Regional Buildings Earthquake Loss Estimation
## 1 Introduction
Due to the enormous workload of information collection, it is mainly used for building-specific seismic performance evaluation or a small number of buildings, and it is challenging to apply it to group buildings at the urban-regional scale. [PERSON] et al. [20] proposed a simplified building earthquake loss estimation method based on the PBEE theoretical framework, which takes the story as the basic unit of response analysis and loss estimation and combines the fragility function of engineering experience with the distribution law of various types of component costs among stories. The framework directly links the seismic demand parameters of the story with the story loss, effectively balancing accuracy and efficiency, which provides a new vision for refined regional earthquake loss estimation. However, this method also requires detailed building construction information, and traditional methods such as field surveys and consulting design data may not be practical for regional buildings. Technical means such as remote sensing mapping cannot obtain the structural arrangement inside the building, which makes it challenging to apply this method to urban group buildings at a regional scale as well. [PERSON] et al. [5] also established an urban seismic elastoplastic analysis method using the story as the basic unit of structural response analysis for seismic hazard simulation and loss analysis in urban areas. The process is based on a nonlinear multiple-degree-of-freedom (MDOF) model, including a shear model for multistory buildings and a flexural-shear model for high-rise buildings, and the response of the structure under a specific seismic shock is obtained through a dynamic time history analysis, which achieves a better balance between accuracy and computational strength. However, the MDOF model in this method is based on the empirical relationships between the mass of the story and the stiffness and structural self-resonance period, whereas the mass of the story is obtained by multiplying the area of the story (obtained by GIS or based on empirical data) by the empirical mass per unit area [21]. Since these values and empirical relationships are deterministic, when the story area is determined, the modeling developed cannot consider the structural uncertainty due to the unknown parameters of the building contents and layout information and the resulting impact on the seismic capacity and losses of the structure. The method was also adopted by [PERSON] et al. [22] for an intensity-based earthquake loss assessment of three typical buildings on the Tsinghua campus, and by combining seismic response with the building component fragility functions and consequences functions in the FEMA-P58 database, the direct earthquake loss and repair time can be obtained. However, the method requires more detailed building construction information, and the information collection workload is extensive, with the establishment of 619 building performance models requiring \(11\) students for four weeks of work by site survey [23]. Even though it is possible to use the Building Information Model (BIM) for assistance in obtaining detailed information on building components [24], only a relatively small percentage of active buildings have been modeled, and the workload required for large-scale BIM is significant. Therefore, applying this method at a regional scale still needs help in effectively obtaining detailed building construction information and modeling it accurately. At present, there are five main ways to obtain regional building construction information: based on census data [6], based on geographic information systems (GIS) [25], based on site surveys [26], based on design information [24], and based on empirical data [21].