# A Component-Based Model for Novel Modular Connections with Inbuild Component
## 2 Parameter Analysis
### Parameter Setting  
The parameters of novel modular connections were shown in Figure 6. According to the experimental results, the bending stiffness of floor and ceiling beams has great influence on the initial stiffness, ultimate strength and continuity of modular connections. In parameter analysis, models were named by F and C followed by beam heights. The reserved construction error between the build-in component and the column leads to the discontinuity of the upper and lower intramodule connections, which is one of the important sources of modular connection deformation between modular units. In the model, the size is represented by G followed by a number. The inbuild component is the main part of the intermodule connection, which can not only locate the position but also enhance the strength of joint panels during construction. The height and thickness of internal inserts are denoted by letters H and P, respectively. After inserting the inbuild component into the side column, the modular connection needs to be tightened by the side plate and split bolts. The thickness of the side sealing plate and the bolt pre-tightening force are respectively represented by S and BL. The beam and column inside the modular unit are welded together through an end plate, which will affect the mechanical properties of the global connections by affecting the strength of the intramodule connection. The thickness of the end plate is represented by D.  
In the experiment, the stiffness can not only prevent the welding failure in advance, but also play a positive role in the mechanical properties of the whole connection. Therefore, stiffeners were set at intramodule connections in all models. The bilinear constitutive model was adopted for the material properties and all members are made of Q345b steel with nominal yield stress 345 MPa (E = 210,000 MPa, \(\
u\) = 0.3). The simplification of material properties would facilitate the development of subsequent theoretical model research. In the experiment, the construction error was set up to ensure the smooth connection between intramodule connections, and it is considered as one of the parameters in the finite element parameter analysis. Hence, the reference of parameter analysis is based on T3, and the construction error was eliminated. According to the above parameter expression rules, the reference model can be named as F250C200H600G0S12P10D12.  
Figure 5: Validation of finite element model.  
The moment-rotation curve directly expressed the mechanical properties of the joint, and can be used as the basis for the design of the joint. For modular building connections, the deformation was more complicated than that of traditional connections. Therefore, in addition to the basic moment-rotation curve, two groups of curves for joint deformation between modular units were defined as shown in Figure 7. Firstly, the relationship between relative dislocation and the bending moment between upper and lower module side columns are shown in Figure 7a. The dislocation between upper and lower columns was defined as g. When the modular units were stacked vertically, the relative dislocation between the side columns will cause additional bending moment to the bottom units. Secondly, the relation between bending moment and relative rotation of upper and lower columns is shown in Figure 7b. The relative rotation between upper and lower columns was defined as CI. The rotation between modular units was related to the story drift, which affected the seismic performance of the building system. Moreover, excessive rotation and translational deformation may cause premature failure of intermodule connection, and then lead to system disintegration and failure.