Nonlinear behavior of high‐damping rubber bearings under horizontal bidirectional loading: full‐scale tests and analytical modeling

Abstract

SUMMARY Horizontal bidirectional loading tests are conducted for real‐sized high‐damping rubber (HDR) bearings with diameters of 700 mm (HDR700) and 1300 mm (HDR1300). The hysteresis loops of these bearings under bidirectional horizontal loadings are compared with those under unidirectional loadings. The results show that the bearing force measurement in the primary direction of loading increases when there is displacement in the orthogonal direction. Unusually, the maximum restoring force in the orthogonal direction to the primary loading direction occurs near zero displacement. On the basis of the observations of the restoring forces, a rate‐independent model is proposed. This model simulates well the test results under both bidirectional loading and unidirectional loading. It can reproduce the irregular restoring forces characteristics around zero displacement as described above. Bidirectional loading induced twist deformation in the HDR bearings that increased local shear strains. This phenomenon results in an early failure as observed in HDR700. The additional shear strain is estimated based on the twist deformation measured by video image analysis. The comparison of the nominal total shear stress demonstrates that the increase of shear stress because of bidirectional loading occurs when the average shear strain is larger than about 200%. The larger the shear strain, the greater the bidirectional effect. It is shown that the nominal total shear stress of average strain of 350% under bidirectional circular loading pattern is approximately the same as the average shear strain of 400% under unidirectional loading. This means that the average shear strain of 350% under a bidirectional circular loading corresponds to a local shear strain of 400%. Copyright © 2012 John Wiley & Sons, Ltd.

Reliability sensitivity analysis of stochastic finite element models

“…On the basis of the test results the model assumes that the restoring force on the rubber bearing is composed of a force directed to the origin of the bearing (non-linear elastic component of the force), and another force approximately opposite to the direction of the movement of the bearing (elastoplastic component of the force). Validation calculations have shown that the analytical model is able to accurately simulate the test results for both bidirectional and unidirectional loading [39]. For a detailed description and implementation of the analytical model that describe the nonlinear behavior of the isolators the reader is referred to [40,39].…”

“…Validation calculations have shown that the analytical model is able to accurately simulate the test results for both bidirectional and unidirectional loading [39]. For a detailed description and implementation of the analytical model that describe the nonlinear behavior of the isolators the reader is referred to [40,39]. A typical displacementrestoring force curve of the rubber bearing is illustrated in Fig.…”

Mechanical behavior of lead rubber bearings under and after nonproportional plane loading

“…As the test setup shown in Figure , it is noted that the upper and lower flange plates of the tested bearings were not twisted during the tests. Taking clockwise positive, the torsional (or twisting) moment at time t exerted on the flange plates because of nonproportional plane loading M t ( t ), as shown in Figure , can be calculated by where F x ( t ) and F y ( t ) are the shear force components at time t measured in X and Y directions, respectively.…”

On rate-dependent mechanical model for adaptive magnetorheological elastomer base isolator

“…This behavior is often reported to be associated with high-damping rubber [31][32][33] and high-damping rubber bearings/isolators [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48]. A number of mathematical models, including rheological models (for rubber material) [38] and constitutive/mechanical models (for rubber devices) [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48], have been proposed to characterize the strain stiffening behavior (in some literatures, it is called strain hardening [33,[36][37]). One of the common techniques in modeling the strain stiffening behavior is to introduce nonlinear power function spring or element.…”