## 5 Conclusions  
In this paper, three rubber bearings (HDRB-LSF, TLRB, and LRB) were analyzed contrastively via comprehensive experimental studies. The properties of vertical stiffness, horizontal equivalent stiffness, horizontal equivalent damping ratio, and hysteretic curves were tested under different vertical pressures, loading frequencies, shear strain values, and pre-pressures. A corrected calculation for the vertical stiffness of the bearing is proposed based on the results of the study. The results show that the HDRB-LSF possesses stable and reliable performance in the rubber isolation system among all the bearing types. Its vertical stiffness could be accurately calculated by our proposed modified equation. The main conclusions are as follows:  
1. The vertical stiffness of the bearings increases with the growth of vertical pressure, loading frequency, and pre-pressure. Based on the premise of the equal total thickness of rubber, the vertical stiffness of LRB with thin rubber layer is much larger than that of TLRB and HDRB-LSF with thick rubber layers, and the ratio of LRB to TLRB for the vertical stiffness value reaches approximately 4. The vertical stiffness of TLRB is smaller than HDRB-LSF with equal conditions, which reflects that the material property and the thickness of the rubber material are equally crucial to the mechanical properties of the bearing. 2. The horizontal equivalent stiffness of LRB and TLRB with the lead core is greater than that of HDRB-LSF with high damping rubber. When the shear strain and the vertical pressure increase, the horizontal equivalent stiffness of the LRB and TLRB declines, and the gap of the stiffness between them and HDRB-LSF keeps narrowing. The hysteretic curves of HDRB-LSF and TLRB are sensitive to the change of pressure, while those of LRB show little difference. The horizontal mechanical properties of the bearings are affected by loading frequency in different degrees. The equivalent damping ratios of the bearings with lead cores remain above 30%, which is larger than those of HDRB-LSF, according to the designed damping ratios of the three bearings. However, the test results have already exhibited the good energy dissipation capacity of the three bearings. The follow-up study of HDRB-LSF will enhance its equivalent damping ratio, reaching the corresponding level of the bearings with a lead core. 3. The errors of the vertical stiffness of the thick rubber bearings between the test value and the theoretical value are exaggerated. Hence, the fitting modification of the theoretical vertical stiffness formula for the HDRB-LSF is carried out. The proposed modification method can better predict the vertical stiffness of the bearing under a certain vertical pressure. Figure 16: Comparison between theoretical value and test value of HDRB-LSF. * In summary, unlike the LRB, which is usually used for horizontal isolation, the application of thick rubber bearings including HDRB-LSF and TLRB can simultaneously help important buildings avoid suffering the adverse effects of horizontal and vertical earthquakes on the structure itself and indoor equipment, as well as to improve the post-earthquake recovery of building structures. Compared with TLRB, HDRB-LSF is better suited for the structures when considering their larger bearing capacity and more environmentally friendly characteristics. It should be noted that the surface pressure on the thick rubber bearings should be strictly limited in engineering applications. This paper presents the results of an analytical, parametric study that aimed to further explore the low shape factor concept applied in three-dimensional isolation for building structures. Conceptualization, Z.G. and V.W. ; Data curation, Z.G. and Y.W. ; Investigation, Y.L., W.Q. and F.H. ; Methodology, Z.G., Y.L. and W.Q. ; Project administration, W.Q. ; Resources, Z.G. and W.Q. ; Software, Z.X. and Y.W. ; Visualization, Z.X. and F.H. ; Writing--original draft, Z.G., Y.L., F.H. and Y.W. ; Writing--review & editing, Z.X.