# A Story-Based Random Structure Modeling Method for Regional Buildings Earthquake Loss Estimation
## 4 Case Study
### SBRS Models Generation  
Based on the building vector information obtained from the open-data platform of Gaode Map, the 3D information model containing the spatial location information is converted and outputted through the data interface of GIS, which can obtain the geometrical information of the building appearance with a high efficiency [25]. Taking the wall-frame structure office building boxed by the red circle in Figure 9 as an example, the lengths of each side transformed from the coordinate point data acquired by GIS are 18.8204 m, 45.6020 m, 18.8201 m, and 45.6029 m, respectively, and the adjusted long side of the building is taken to be 45.6 m, the short side to be 18.8 m, and the height to be 26.4 m. The ranges of values of the parameters of the SBRS model are as follows:  
1. Story height. The story heights of office buildings are generally in the range from 3.0 to 3.6 m.
2. Bidirectional main and secondary beam spans. The main beam's span range in the building's short side direction is usually from 6 to 8 m, the long side direction is from 4 to 6 m, and the secondary beams are laid out at spacings from 2 to 3 m.
3. The cross-sectional area of the frame column. It can be assumed that the square columns have side lengths ranging from 600 to 800 mm, with 50 mm as the basic unit of increase or decrease. 4. Material strength. The concrete strength grade is C30-C40, and the thickness of the infill wall is uniformly taken at 200 mm. The ratio of the cross-section to the floor plane is taken as 5-8% according to engineering experience. According to GB 11968-2020, the Standard for Autoclaved Aerated Concrete Blocks [35], the commonly used grade markings for autoclaved aerated concrete blocks are B05 and B06. The corresponding dry weights are 500 kg/m\({}^{3}\) and 600 kg/m\({}^{3}\), considering mortar, plaster, and other factors, and the integrated volume weight is 900 kg/m\({}^{3}\). 5. Shear wall section size. The shear wall thickness is 200 mm, and the ratio of the shear wall cross-sectional area to the floor area is from 2% to 3%; for office buildings, in addition to stairwells and elevator shafts outside, the other shear wall section is simplified to take the \"1\" type column-wall combination section. 6. Number of stairwells and elevator shafts. According to the building area, two sets of evacuation stairs should be set up to meet the requirement that the straight distance to the evacuation door between the two safety exits is not less than 40 m in the Code for Fire Protection Design of Buildings [36]. According to the floor area projection of three elevators, the short side of the building, in the direction of the main beam span range, meets the unilateral layout of the space requirements. 7. Other parameters. According to the provisions of Article 3.1.1 of GB 50009-2012, the Load code for the design of building structures [37], the loads of the building structure are divided into three categories: permanent load, variable load, and accidental load, and only the first two categories are considered in this paper. Among them, the constant loads such as fixed equipment and long-term storage outside the building body are considered as 1.1 times the load of the building body, and for variable loads, standard, combined, frequent, or quasi-permanent values should be used as representative values according to the design requirements. The standard value of floor distributed live load is 2.0 kN/m\({}^{2}\), the combination value coefficient is 0.7, the frequency value coefficient is 0.5, the coefficient of live load reduction according to the stories is 0.65, and the structural damping ratio is 0.05. Assuming that each of the aforementioned random variables follows a uniform distribution across their respective value ranges, the LHS method randomly combines the selected variables to generate 100 SBRS models and perform axial compression ratio checking to screen out the unqualified samples. According to the GB 50011-2010 [32], the limit value of the axial compression ratio for RC wall-frame structures is 0.90.