## 3 Experimental Analysis of the Bearing Capacity of the Vertical Member
### Experimental Analysis of the Shear Capacity of the Sleeve on the Vertical Pole
#### 3.2.4 Finite Element Comparative Analysis of the Shear Capacity of the Sleeve on the Vertical Pole  
The sleeve model was composed of a vertical pole and a sleeve, and the model was established according to the actual size of the element. The vertical pole and the sleeve were one entity; the weld element unit system was ignored. The vertical pole and the sleeve material were both made of _Q235_ steel. As shown in Figure 5, the proximate global size was set to 0.02, and the meshing method was set to Sweep. The vertical pole and sleeve grids were automatically divided. The numerical model is shown in Figure 19. In order to make the simulation and the experimental situation the same, the connection at the bottom end of the sleeve was fixed and a vertical uniform load was applied to the upper vertical pole, that is, the lower end of the sleeve restricted the translational and rotational degrees of freedom in three directions. The upper end of the sleeve restricted the translational degrees of freedom in the other two directions except for the vertical directions and restricted all the rotational degrees of freedom at the upper end. The load adopted the step-by-step force control loading method. Vertical displacement control was adopted for this model, and the specimen failure was defined as damaged when the maximum vertical deformation displacement of the specimen reached 5 mm. The deformation displacement of the sleeve under normal working conditions is shown in Figure 20a, and the shear stress diagram of the sleeve is illustrated in Figure 21.  
Figure 19: Model of a sleeve shear.  
Figure 18: Shear failure modes of sleeves: **(a)** SJ-1; **(b)** SJ-2.  
According to the ABAQUS calculation results, the following conclusions can be drawn:  
1. Regarding shear capacity, the results of the \(FEA\) were compared with the average values of the five groups of specimens, and Figure 20b was obtained. The trends of the two graphs of the simulated and experimental values were different. The experimental load-displacement curve increased slowly in the middle of the loading period, while the load-displacement curve obtained by the finite element method increased linearly throughout the experiment, which indicated the necessity of establishing the welding unit when studying the shear capacity of the sleeve. However, the \(FEA\) results for the ultimate shear capacity were very accurate, which verified the accuracy of the finite element model to predict the ultimate shear capacity of the sleeve.
2. Regarding stress distribution, according to the simulation analysis and experimental results, when the sleeve was sheared, the stress concentration area was located mainly in the main material near the connection between the sleeve and the vertical pole. The results were consistent for the simulation analysis and experiment.
3. Regarding failure mode, according to the simulation analysis and experimental results, the sleeve shear failure mode was the result of stress concentration that led to different degrees of plastic buckling deformation of the vertical pole and the sleeve; this buckling eventually led to the loss of bearing capacity by the specimen. The results showed that the bearing capacity of the sleeve was stronger under shear force.  
and corner poles. The variation in the stability bearing capacity of the vertical pole was studied, and the buckling form of the vertical pole was determined.