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In this paper, the isolation performance of truss string structure on rubber bearings considering relative rotation between the upper and lower surfaces of the bearings is studied. Through the test and finite element analysis, the following conclusions are obtained: the initial rotation angle has a great influence on the horizontal stiffness of the isolation bearing. In practical engineering, the loss of prestress, the change of temperature and general vertical loads will produce rotation angle between upper and lower surfaces of the bearings. Therefore, the numerical analysis of the truss which consider rotation angle of the rubber bearings is carried out. The results show that the horizontal acceleration responses of the truss decreases, and the displacement of the isolation bearing exceeds the code limit. Therefore, the practical engineering structure should consider the influence of the rotation angles.

In view of the differences between Chinese and German regulations of bolt end distance, experiments for connection specimens with different bolt end distances were designed and conducted. The finite element models took into account the material nonlinearities, geometry nonlinearities and contact nonlinearities. The major factors were selected, and parametric studies were performed. It is found that FEA (finite element analysis) were in good agreement with the experimental results. The ultimate carrying capacity increases with the increase of bolt end distance. It is recommended to extend the minimum allowable bolt end distance to within 1.2d0, but it’s carrying capacity should be appropriately decreased. When the bolt end distance e1 is less than 1.2d0, the bolts were torn off at the end. When the bolt end distance e1 is greater than or equal to 1.2d0, the specimens damaged of their ultimate carrying capacities. The increase of bolt diameter and number has little influence on the ultimate carrying capacities of specimens, but all of them indicate good ductility. Finally, using the analysis data and combining with the calculation method of the ultimate bearing capacity of the bolt connection in Chinese codes, the proposed formula when the bolt end distance e1 is in the range of 1.2d0 to 4d0 were proposed, and the finite element calculation verification is carried out.

In order to analysis the bearings rotation of large-span spatial structures, the horizontal mechanical properties of the rubber bearings with relative rotation between upper and lower faces are discussed. Firstly, horizontal mechanical properties of rubber bearings without rotation are analyzed by finite element software ABAQUS. Then their horizontal mechanical properties along same direction of horizontal displacements, and the varying trends of horizontal stiffness and shear strains are obtained. Finally, the finite element analysis results are compared with experimental results. The analysis results show that, when shear strains are small, the horizontal stiffness of bearings decreases with the increases of the rotation, when shear strains are great, horizontal stiffness of bearings increases with the increases of the rotation, and finally tends to equal. The horizontal stiffness increases with the increases of the rotation. The vertical pressure has little effect on the horizontal stiffness in the engineering stress range.