## 4 Naming Process for Bridge Components
### Basic Bridge Geometric Modeling and Information Reassigning
Rule: If objects \(i\) and \(j\) satisfy Equation (3), then it is defined that \(S_{mn}(i)=S_{mn}(j)\). \[\{|p_{x}(i)-p_{x}(j)\leq\varepsilon|\}\wedge\left\{\exists a\in j,\exists \beta\in i:c(i)^{\beta}=c(j)^{\alpha}\right\} \tag{3}\]

Here, \(p(i)\) and \(p(j)\) are the centroid (in the local coordinate system) of the objects \(i\) and \(j\) that are arranged along the axis of the spanwise bridge direction (\(\Upsilon^{\prime}\)-direction). \(\varepsilon\) is the tolerance that processes the exceptional case of modeling, in which an object is divided into two. Its value should be higher than zero, but, when it is smaller, it divides an object more strictly, which may vary depending on thetarget model. In this study, the authors used \(\varepsilon=1\) mm. \(c(i)^{\beta}\) is the centroid coordinate values of the \(\beta\)th face of object \(i\), and \(\alpha\) is the nearer face, while \(\beta\) is the further face, with reference to the axis of the bridge spanwise direction. In other words, the rule is the identification of identical objects from among recurrently arranged objects, in terms of the semantic classification of the bridge. The applicability of the developed algorithm was verified by the application to the sample bridge model shown in Figure 6:0 The sample bridge consists of two girder intervals and two span intervals, and the intervals used for the algorithm verification are the section interval (_Assembled Assembly_) and the diaphragm and crossbeam (_Parts Assembly_) inside the section. As mentioned earlier, the _Girder_ and _Span_ properties of each component have already been entered. The elements to be automatically identified were 18 sections, 14 diaphragms, and 12 crossbeams. Algorithms were first applied to the sections, and subsequently to the diaphragms and crossbeams. The results appeared in the form of _Span_ID-Girder_ID-AssembledAssembly_ID-PartsAssembly_ID_, using the elements of the set proposed in Equation (1). The 44 individual components all contained the identifiers in the correct format, as shown in the following example. During this process, for objects that extend over multiple elements, we adopted the expression of all included elements. This was true in the case of D, where the property _Girder_1,_Girder_2_ was generated as the _Girder_ property. A: Span_1-Girder_1-Section_4

B: Span_1-Girder_2-Section_2-Diaphragm_2

Figure 6:1 Sample bridge model for examining the automatic naming algorithm. Figure 6:2 Examples of object feature set for a bridge model. C: Span_1-Girder_2-Section_4-Diaphragm_1

D: Span_1-Girder_1,Girder_2-Section_3-CrossBeam_1

E: Span_2-Girder_2-Section_1

## 5 Discussion

To verify the applicability of the bridge information model containing functional semantic information, we examined whether it can be applied to the basic quantity take-off of an actual bridge and information linkage with the external information, and whether it is possible to regenerate a model through an IPF-based semantic search. In an actual bridge design process, the result of the quantity take-off includes the as-built structure, the temporary facilities, and the components of the discarded part. However, this study aimed to examine whether the retrieval of the functional components can be used for quantity take-off. Therefore, only the as-built bridge model as appearing in the design document was used for the quantity take-off. Since the material quantity in the final product directly relates to the volume of the product, there is no room for problems, as long as the geometric information is correctly processed. However, for a more advanced form of decision-making support, such as the quantity take-off of bridge members with identical functions, or the quantity take-off of a specific member, the model must be able to provide information in various forms. This involves the critical requirement of accurate identification information for the bridge components, which can be said to be redundant geometries that represent the real world.