# Research on 3D Digital Technological Process of Construction Products with Model-Based Definition
## 4 Application Examples and Discussion
### Infill Wall Masonry Process Information Expression
#### 4.2.2 Infill Wall Masonry Process Design Model  
1. Parameterized unit creation  
Referring to Sections 3.2 and 4.2 of this paper, the parametric elements to be created for the Revit-based masonry process design model of infilled walls include beams, slabs, columns, bottom lime-sand bricks, concrete plus blocks, lime joints (horizontal and vertical), skin count rods, and top oblique bricks. The bottom grey sand brick and top inclined brick were created by the nested method, which parameterizes the masonry rules and methods of the bottom and top of the infilled wall masonry so that the change in the model could be driven by changing the parameters in a certain range.
2. Modeling for the construction process  
Referring to Sections 3.2 and 4.2 of this paper, the modeling of the construction process of the infill wall masonry works includes the pre-model, the auxiliary process model, the key process model, and the process detail practice model.  
(1) The creation of a pre-model  
The beam plate column was created according to the design requirements of the drawings and the location of the masonry filling wall project. As shown in Figure 3, the spacing of the column was the masonry length of the wall, and the spacing of the beam plate was the masonry height of the wall.  
(2) Establishment of the auxiliary process model  
For the masonry infill wall, it is necessary to set the positioning line and the wall sideline, use the line hammer to measure the verticality, place the skin pole to assist the masonry wall, and establish the corresponding model in the process design model, as shown in Figure 4.  
(3) Establishment of the key process model  
To show the details of the process, the key nodes of the infilled wall masonry project need to be combined with the structural design requirements of the specific project and the mandatory provisions of the sub-project in the relevant specifications. Considering that there are many quality control points in infilled wall masonry engineering, this paper takes the practice of masonry tie bars as an example to illustrate the effectiveness of our method.  
Figure 4: Process content modeling based on the infill wall masonry process design model.  
Figure 3: The preposition model of the infilled wall masonry process design model.  
According to the design specification, when the infill wall and frame are not separated, it is appropriate to configure two tie bars with a diameter of 6 mm every 500 mm along the column height. Meanwhile, the length of the steel bar into the infill wall should not be less than 700 mm. A hook of 90\({}^{\circ}\), extended into the infill wall or column, should be made at the end of the tie bar. The tie bar should be reasonably laid in the horizontal ash seam, and the vertical spacing should meet the modulus requirements of the specification and masonry. The modeling of masonry tie bars should fully consider these key process nodes, as shown in Figure 5.  
(4) Creation of the process detail practice model  
In the masonry process, following the 'three-one masonry method' (i.e., a brick, a shovel of ash, and a rub masonry method), horizontal ash seam and vertical ash seam are evenly distributed, and the maximum length of the ash should not exceed 800 mm. Meanwhile, to meet the overlapping of staggered joints, a reasonable layout of the brick arrangement is set in the modeling. The overlapping length of the autoclaved aerated concrete block should be no less than 1/3 of the block length, and the vertical joint should not be greater than 2 skins. The block length was 600 mm, the overlapping length was greater than 200 mm, and there was no vertical joint.