## 7 Case Study  
The IFC-based and graph database-based framework is validated through an engineering case of prefabricated buildings. In this case study, the comprehensive process of realizing, twinning, and analyzing the IFC-based 4D construction management information model of prefabricated buildings is executed. The result illustrates that this framework can enhance the managers' control of processes by effective data interoperability and automatically analyzing construction schedules to prevent possible delays in advance. Realizing the IFC-Based 4D Construction Management Information Model of Engineering Case's Prefabricated Building  
The engineering case selected is an academic building in Shanghai, China, with a total construction area of 135,858 square meters. The south tower of this building has 13 floors, and the north tower has 21 floors. According to the framework proposed in this paper, an IFC-based 4D construction management information model of this case study's prefabricated building is established. The central part of this created IFC-based 4D construction management information model is shown in Table 7. A lot of components' information is omitted from this listing, therefore, the span between the number of IFC file instances is large. In this IFC model, the project (#1) has a general construction task named TaskGroundLevel (#1036), which is composed of floors 1-13 construction tasks (#1039-#1063). Every floor's construction task includes four summary tasks: fabrication summary task (#1065), transportation summary task (#1091), hoisting summary task (#1171), and installation summary task (#1143). Furthermore, taking fabrication summary task as an example, fabrication summary tasks nested by slab fabrication summary task (#1067), slab fabrication summary task (#1072), and roof fabrication summary task (#1085). The slab fabrication summary task is composed of tasks corresponding to specific components (#1067). Meanwhile, for each task of a specific component, the process information, resource information, and costs information related to the task are established in the information model. Taking the fabricate task of the 1 st-floor slab as an example (#1067), the process information, labor resource information (#1247), material resource information (#1248), equipment resource information (#1249), cost information (#1253, #1254, #1255), schedule network analysis (#1257), and delay analysis (#1261, #1265) corresponding to the task are associated to it. Twinning the IFC-Based 4D Construction Management Information Model of Engineering Case's Prefabricated Building to Graph Database  
Based on the algorithm proposed in Section 5, the IFC-based 4D construction management information model of the engineering case is twinned into the graph database to help the participants operate the IFC information model's data. The interoperation platform based on the graph database is shown in Figure 10. Different colored nodes represent different entities in this figure, and the edge between two nodes represents the relationship between two entities. Further, the entities' attributes are saved as the corresponding nodes' properties. In this case, the twinned IFC-based information model is uploaded to the cloud. Therefore, the participants in different construction parts can access the database and interoperate the construction information. During the actual construction management, the modification of construction task information is often accompanied by the modification of related resources, cost, and other information, which is troublesome to operate. One of the enormous benefits of adopting the approach presented in this paper is that the participants can easily retrieve and operate the information they need, and all the related information associated with it via the graph's edge. Another benefit to twin the IFC-based 4D construction management information model into a task-centered network is that the graph database-based algorithm can complete networks' analysis that IFC files and Relational Database cannot complete.