# Flexural Performance of Removable Deck Slabs with Fixing Device Details
## 3 Fixing Device of a Removable Deck Plate
### Finite Element Analysis for Fixing Device  
Finite element analysis was conducted to investigate the load acting on the contact surface between the fixing device and the reinforcing bar, as well as to identify the fixture's most vulnerable component. The shape of the fixture was determined using MIDAS FEA [11], a nonlinear analysis program developed exclusively for bridges and civil structures as part of the MIDAS family of programs, in collaboration with TNO DIANA. MIDAS FEA can conduct linear static analysis and material nonlinearity, heat of hydration, fatigue, crack, and contact analysis.  
The analysis model shown in Figure 3 was created with the upper part of the fixing device being biaxially symmetrical at the center. To reduce the analysis time, 3D analysis was conducted by modeling only one-quarter of the structure. Solid 3D elements were modeled to enable both linear and nonlinear analyses that incorporated surface conditions, material nonlinearity, and deformation. The yield strength specified in KS D 3861 [12] was used to verify the safety of the design strength. SS275 steel was chosen for the finite element analysis, using a nominal yield strength of 275 MPa, and a bilinear model was applied. The elastic modulus of the material is 205,000 MPa, and the corresponding yield strain is 0.001341.  
According to a prior study by [PERSON] [13] of various types of meshes, hexahedral elements can increase the convergence of analysis and accuracy of results when steel materials with complex shapes are involved. However, another study [14] reported no significant difference between the results of analyses of hexahedral and tetrahedral shapes. Given the curved surfaces of the fixing device in this study, hexahedral elements could result in longer analysis times. Therefore, to shorten the analysis time, tetrahedral elements were modeled.  
Figure 3a depicts the point condition. In a previous study [15] that analyzed symmetric models, only a part of the model was used to reduce the analysis time, and point conditions were set appropriately on the contact surface. Because the fixed hardware was biaxially symmetrical, only the one-quarter part was modeled, and the support condition was set as a hinge for the Y direction only. This not only shortened the analysis time, but also allowed for the generation of rotational deformation only in the Y-axis direction as the fixing device was simply placed on the steel in the actual connector.  
When concrete is poured during construction, a load is transmitted in the Z direction through the bolts used for fixing the formwork (Figure 2). In this study, the load was applied in consideration of the applied area of the bolts, as shown in Figure 3b.  
The results of the finite element analysis are presented in Figure 4, with von Mises stress used to evaluate stress distribution with respect to yield. The stress was concentrated in the curved part at the starting point of the load control. The variables affecting the shape of the fixing device were determined by the results of the finite element analysis.  
Figure 3: FEA modeling of fixing device: (**a**) boundary condition; (**b**) load condition.