# A Web-Based BIM-AR Quality Management System for Structural Elements
## 4 On-Site Test of the Proposed BIM-AR QM System and Results  
The proposed system has been tested in the case study of a reinforced concrete building under construction in Budapest, Hungary. Trial inspections have been performed on one level of the building to check the quality of structures and test the developed system. The test followed a stepwise procedure. First, the 3D model of the building was created in Autodesk Revit@and exported to IFC format. Secondly, the model was imported in Synchro Pro@establishing the connection between schedule information and the building elements and then exported again in IFC format. Such an IFC 4D model was finally imported into the developed system to synchronize the quality information with the physical and schedule information of the building and to generate the web-based checklist and the link for accessing the AR application. The Gamma AR Pro@application was used as the AR platform to visualize the BIM model on site. Such application directly uses the IFC format and gives the possibility of accessing information regarding the elements by just clicking on the object. This application positioning system is marker-less, and uses depth-sensing as the tracking system to overlay the BIM model to the reality on site. For positioning, the inspector needs to choose the floor and room and then select two corners of a wall or column in the model to superimpose it to the reality. An Apple iPhone 7@was used as the mobile device for the AR application. The project used for the test is an office building with reinforced concrete structure which is being reconstructed after demolishing the old one, to match the architecture of the building next to it. Considering the building is being used as offices, based on EN1990-2002 Annex B [38], the consequence class CC2 has been chosen. Moreover, based on EN13670 [35], Execution Class 2 has been considered for assigning the range of admissible tolerances and the severity of the inspection. A total of 36 elements were inspected and the results were recorded. At the time that the test was done, most of the structural elements had been constructed and the activities related to the architectural part of the project were ongoing. Therefore, the inspection lots related to the \"after-execution\" phase of QC and were added as an input to the web-based checklist. In this phase there are no inspection lots related to formwork and rebar elements; however they were modeled in Revit@and then exported in IFC to examine how the inspection could have been performed on site using AR. In this way, it was also possible to assign and then retrieve their corresponding quality parameters. In Figure 9, the model of a column is shown, together with its on-site visualization using the AR application. Inspection records were saved as XML and visualized using the color-coded model of the quality system; in this way it is also possible to find the location of the defects (see Figure 10). Furthermore, the dashboard of the quality status of the projects shows the results of the inspection (see Figure 11). During the inspection test, the response was negative in three cases (8% of the items checked); all of them concerned the concrete placement, two were related to walls, and one was related to a slab. Two of the failed inspection lots concerned the geometry and one concerned the material. These cases are represented in Figure 12.  
Figure 8: AR application user interface. (**A**) Opening the file and choosing the level. (**B**) Choosing an element for positioning. (**C**) Positioning by superimposing two corners of the element. (**D**) Augmented column with formwork. (**E**) Hiding formwork. (**F**) Column reinforcement. (**G**) Retrieving element properties and linking the checklist web address. (**H**) Accessing the selected element quality checklist.