FEA Validation of the Moment-Rotation Relationship of Unbonded Fiber-Reinforced Elastomeric Bearings
Lecture Notes in Civil Engineering
Elastomeric bearings are widely used for base isolation as well as accommodating displacements in bridges. Fiber-reinforced elastomeric bearings (FREBs) have been shown to have similar performance as steel-reinforced elastomeric bearings (SREBs). In addition, they are lighter, and potentially cheaper and easier to manufacture. Unbonded FREBs exclude the stiff and heavy steel end plates used to mechanically fasten the bearing to the top and the bottom surfaces. Due to the lack of a connection, lift-off (i.e. the separation between the superstructure and the bearings) could occur under certain combinations of large rotations and relatively low axial stress. This causes the superstructure to partially lose contact with the bearing and thus makes the effective load supporting part of the bearing decrease. As a result, some nonlinearities are developed in this process which renders the problem to be more complex than the bonded case. Canadian and American bridge design codes (CSA S6 and AASHTO) have different regulations on if lift-off is allowed to occur. In this paper, finite element analysis (FEA) models are developed to validate an existing analytical model describing the lift-off behaviour of FREBs. Note that the validation of the analytical lift-off model with FEA has yet to be investigated. Three infinite strip-shaped bearings with different number of elastomeric layers (5, 8 and 11) are simulated using ABAQUS. The moment-rotation relationships are compared and the results show good agreement between the analytical and the numerical models.
Bai, Junfu; Van Engelen, N.; and Cheng, Shaohong. (2023). FEA Validation of the Moment-Rotation Relationship of Unbonded Fiber-Reinforced Elastomeric Bearings. Lecture Notes in Civil Engineering, 241, 253-264.