## 3 BIM-Based Hazard Recognition
### BIM-Based Risk Rating Estimation
#### 3.2.1 BIM-Based Hazard Recognition Method  
For BIM-based risk assessment, we intended to conduct an open BIM-based assessment using industry foundation classes (IFC) data, a standard information format. The evaluation was conducted based on the IFC-defined building object (IfcBuildingElement). Table 6 shows the information contained in the IFC architectural objects as examples of IFC building objects [39]. In addition, connections and other property information such as HasOpening, ConnectedFrom, and ConstrainedInStructure are also defined. A BIM-based risk assessment was conducted by minimizing additional definitions based on the basic definitions of the objects included in the sub-items of IfcBuildingElement.  
In the case of a fall disaster, the frequency of occurrence has a high value, and in the case of a fall disaster occurring at a low height, it shows a higher frequency. The results of the risk rating evaluation according to the height of the fall disaster are shown in Table 3. As shown, the height of the fall has a small impact on the severity of the disaster, and there is a higher risk rating when the occurrence height is lower. In other words, the severity factor of a fall disaster has a maximum value of 4, and the frequency of occurrence is the most influential effect on this disaster. Therefore, the higher the exposure to a fall disaster is, the more dangerous it is, so a fall disaster occurring at a low height has a higher risk.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Building Object** & **Definition** & **Name** & **Content** \\ \hline \multirow{8}{*}{IfcBeam} & \multicolumn{2}{c}{NominalLength} & - \\  & \multicolumn{2}{c}{CrossSectionArea} & - \\  & \multicolumn{2}{c}{OuterSurfaceArea} & - \\  & \multicolumn{2}{c}{TotalSurfaceArea} & - \\  & \multicolumn{2}{c}{Definition} & \multicolumn{2}{c}{GrossVolume} & - \\  & \multicolumn{2}{c}{NetVolume} & - \\  & \multicolumn{2}{c}{GrossWeight} & - \\  & \multicolumn{2}{c}{NetWeight} & - \\ \hline \multirow{2}{*}{Local Placement} & \multicolumn{2}{c}{IfcLocalPlacement} & - \\  & \multicolumn{2}{c}{World Coordinate} & - \\  & \multicolumn{2}{c}{System} & \\ \hline \multirow{2}{*}{Geometric Representations} & \multicolumn{2}{c}{SweptSolid} & \multicolumn{2}{c}{Solid} \\  & \multicolumn{2}{c}{Representation} & \multicolumn{2}{c}{Profile} \\ \cline{1-1}  & \multicolumn{2}{c}{Representation} & \multicolumn{2}{c}{Extrusion} \\ \hline \hline \end{tabular}
\end{table}
Table 6: Data structure of IfcBeam object.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Hazard**} & \multicolumn{3}{c}{**Risk**} & \multirow{2}{*}{**Control Measure**} & \multicolumn{3}{c}{**Residual Risk**} & \multirow{2}{*}{**Final Risk**} \\ \cline{2-2} \cline{6-7}  & **Likelihood** & **Severity** & **Risk Rating** & & **Likelihood** & **Severity** & **Risk** \\ \hline \multirow{3}{*}{Worker Fall} & \multirow{3}{*}{3} & \multirow{3}{*}{4} & \multirow{3}{*}{12} & Barricades/Guard rails & 2 & 4 & 8 \\ \cline{4-7}  & & & & Anchorage point & 1 & 4 & 4 \\ \cline{4-7}  & & & & Warning signs & 2 & 4 & 8 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Example of design-for-safety review template.  
An evaluation system was derived by collecting scenarios in which fall disasters occur to establish a scenario for evaluating the risk of fall disasters. The guidelines for preventing fall disasters distributed by the Korea Occupational Safety and Health Agency (KOSHA) were followed [40; 41; 42; 43]. According to the item \"Use a high work platform secured at a height of 2 m or more from the ground\", it is assumed that there is a possibility of exposure to a fall disaster when working at a height of 2 m or more from the ground. In other words, a height of 2 m is the minimum condition that can cause a fall disaster. The process of deriving the risk assessment items from the BIM object is as shown in Figure 2, assuming the risk assessment conditions for the fall disaster are based on the condition of \"at least 2 m above the ground\".