# Research on the Intelligent Construction of the Rebar Project Based on BIM
## 8 Conclusions  
In this work, a program for automatic generation of rebar parametric model in Revit was developed, which improves the modeling efficiency and modeling accuracy of rebar engineering. Combined with WPF technology, the program operation interface was developed to increase the operability of the program, realize the automatic export of 2D rebar CAD drawings from the 3D model of rebar, complete the forward design process from 3D model to 2D drawings, and provide a reference for the subsequent research on the forward design of rebar engineering automation. Reinforcing bar information was exported, and the bar cutting method was analyzed. Through the development of the mixed reality device HoloLens2, the interaction between the rebar model and the human hand was realized, which improves the visualization of the rebar engineering, and provides a reference for the follow-up construction operation and maintenance research. Based on the above steps, the process of intelligent construction of steel bars was realized, and we conclude the following:  
1. Use the C# programming language for secondary development based on Revit and use the rebar generation method in the Revit API. Realize the automatic generation of longitudinal rebar model, stirrup model and additional stirrup model in Revit. The user can customize the diameter of the rebar to be generated, the thickness of the protective layer, and the number of longitudinal rebar. According to the height of the rebar area entered by the user, the program can automatically generate stirrups in the encryption area and stirrups in the non-encryption area. At the same time, various annotation information of the steel bar BIM model can be automatically generated, and CAD drawings can be automatically exported. To a large extent, the repetitive work is reduced, the modeling efficiency is improved, and the inaccurate and non-standard models caused by human errors are avoided. The forward drawing of the rebar project is realized, which can better improve the work efficiency of the designer.
2. In order to realize the fully automatic processing of steel bars, using Revit secondary development technology combined with Visual Studio NuGet toolkit, the function of exporting the location information and cutting information of the steel bar BIM model was realized. The steel bar information can be directly exported to an Excel table, which can be used to read the information of the steel bar automatic processing equipment. The whole process of automatic processing of steel bars was realized, avoiding the mistakes that may be caused by manual operation. It can improve the rebar processing rate and save labor costs. At the same time, it also avoids the safety problem of workers directly operating the machine to a certain extent.
3. A study on the application of BIM+MR technology in steel bar engineering. Unity3D develops the HoloLens2, a mixed reality device. The Revit structural rebar model was imported into Unity3D to realize the interaction of the Revit model with the human hand in mixed reality. It enables owners, design, engineering, construction and other parties in the engineering construction industry to experience and interact with realistic 3D models in a virtual environment, accelerate design iteration, and help to realize digital construction guidance.  
Accordingly, it makes the intelligent construction of steel bars possible and provides a reference for subsequent steel bar construction research.  
Author Contributions: Conceptualization, D.W. Writing--original draft preparation, Y.H. All authors have read and agreed to the published version of the manuscript.
* This research was funded by [Natural Science Foundation of Shanghai] grant number [18 ZR1414500].
* Not applicable.
* The authors declare no conflict of interest.