# A Component-Based Model for Novel Modular Connections with Inbuild Component
## 2 Parameter Analysis
### Parameter Analysis Results
#### 2.3.5 Dimension of Floor and Ceiling Beams  
Different from traditional assembly joints, modular building joints consist of two beams. Many studies proved that the height ratio between floor beam and ceiling beam has significant influence on the mechanical properties of modular connections and systems. In order to better understand the influence of geometric dimensions of double beams on mechanical properties of joints, six groups of finite element models were set up under the premise that geometric dimensions of floor beams were no less than that of ceiling beams. F200C200, F225C200, F225C225, F250C200, F250C225 and F250C250 were considered, among which F250C200 was the reference model. The result moment-rotation curves were shown in Figure 25. Compared to the reference, the initial stiffness of F250C225 and F250C250 models increased by 16.6% and 19.9%, respectively, and the ultimate moment bearing capacity increased by 3.63% and 12.7%, respectively. F225C200 and F200C200 models reduce the height of floor beams on the basis of the reference model. The initial stiffness was reduced by 2.4% and 18.2%, respectively, and the ultimate bearing capacity was reduced by 10.9% and 18.9%, respectively.  
The moment-dislocation curves were shown in Figure 26. The curves were overlapped in the elastic stage and began to separate when the moment reached 125 kNm. Under the same bending moment, the higher the joint of double beam, the smaller the dislocation between columns. The relative displacement of the F250C225 model and the F250C250 model was 1.73 mm and 2.38 mm, respectively, at maximum moment, which was 12.3% and 54.5% higher than that of the F250C200 model. The relative displacement of the F225C200 model and the F200C200 model was 1.41 mm and 1.31 mm, respectively, when the bending moment reaches the maximum value, which was reduced by 8.4% and 14.9%, as compared to the reference model. The rotation difference-bending moment curves were shown in Figure 27. The curves of the F200C200 model, F225C225 model and F250C250 model which  
Figure 24: Stress distribution of connections with different construction errors.  
Figure 25: Moment-rotation curves of connections with different beams height.  
had the same height of floor beam and ceiling beam were significantly lower than those of other models. The inflection points of the F200C200 model, F225C225 model and F250C250 model appeared at about 200 kNm, 230 kNm and 260 kNm, respectively. The inflection points of the F250C200 model, F225C200 model and F250C225 model appeared at 150 kNm, 175 kNm and 225 kNm, respectively, and the curves diverged upward after reaching the inflection point, indicating that the rotation difference between upper and lower columns further expanded.  
The stress distribution along x direction of the twin beams and the Mises stress distribution of connections were shown in Figures 28 and 29, respectively. By comparing F200C200, F225C200 and F250C200, it can be concluded that increasing the height of the floor beam can reduce the stress concentration area and then improved the stiffness and strength of upper intramodule connection. The same conclusion can be drawn by comparing F250C200, F250C225 and F250C250 for lower intramodule connection. For models with equal height of twin beams (F250C250, F225C225, F200C200), the strain was symmetrically distributed with respect to the interface of twin beams. The force transmitted from the double beams was equal to the intermodule connection, so the continuity of the joints is better than that of the joints with unequal heights of the double beams.  
Figure 27: Continuity index-moment curves of connections with different beam height.  
Figure 26: Moment-relative dislocation curves of connections with different beam height.