# Interoperability Analyses of BIM Platforms for Construction Management
## 2 Materials and Methods
The first one is aimed at checking BIM interoperability through IFC standards and is performed by investigating if 3D and 4D information can be correctly transferred via IFC files. A sample 3D model was built in Tekla Structures, the construction sequence of each structural element was defined to obtain a 4D model, and the sample model was exported/imported through IFC from Tekla Structures to the other packages (Edificius, Navisworks, Synchro Pro, usBIM.viewer+, and Solibri Model Checker) to be tested in order to detect missing or conflicting schematic/metadata information. The second simulation test (BIM Interoperability through Gantt Charts - Design2 Management) regards the assessment of Gantt Chart exchanges produced by Tekla Structures and imported to CPM software packages. According to the schema where the modeled structure in Tekla Structures is divided into different tasks by assigning a generic duration to each of them (start and end dates), the corresponding Gantt Chart was transferred through XML format to the CPM software packages. The third simulation test (BIM Interoperability through Gantt Charts - Management2 Design) can be considered as the reverse of the second experiment. Sample Gantt Charts were created in each CPM software and exported via XML to Tekla Structures. A summary workflow of the experiments is provided in Figure 2.  
Figure 2: Workflow summarizing the three approaches followed for assessing data exchange procedures. For each test, the goal is to investigate the following issues: how much data can be exchanged from one tool to another; the possibility of exchanging a 4D BIM model between various BIM software packages by using only IFC, without loss of detail or data conflicts; the quality and processability of the transferred data; the presence of changes in the Gantt charts after export and import operations; the level of adverse effects of lost data for the collaborators. The sample BIM model to be used as a starting point and reference for the subsequent analysis was created with Tekla Structures. The modeled structure is a building with three upper floors with a flat roof and one basement at 2.60 m depth. The height and length of the building are 9.10 and 19.00 m, respectively. The quantity, dimensions, shape, material type, location, and orientation of the elements were included in the model, along with some structural element details such as the stairs, also including the steel one where the bolts, bolt types, and welds were clearly defined. Figure 3 shows the sample model. To obtain a 4D model, phases were assigned to each representative element. The selected elements are shown in Figure 4. Phasing names were chosen according to the relevant tasks, which were supposed to be performed in a sequential way. Based on such phasing, the most relevant information needed to create a Gantt chart were defined. In particular, the fields \"Task Names\" were defined according to the designed elements; additionally, both \"Start Date\" and \"End Date\" were defined in a generic way but according to the previously defined phasing. Once all the relevant features of the sample model were in place, in order to perform the interoperability tests, the sample model was exported in IFC format, with IFC2x3 import and export certificates being granted [30]. Among the available Model View Definitions, the Coordination View 2.0 option was chosen, since it is focused on the coordination of architectural, structural engineering, and building services tasks in the design phase. The corresponding Gantt chart was exported in XML format. The result is shown in Figure 5.  
Figure 4: Elements selected from the sample model for the assessment of the data exchanges. Figure 3: Front (left) and back (right) views of the sample model.