INTERNATIONAL CONGRESS ON ENGINEERING AND LIFE SCIENCE, Kastamonu, Turkey, 26 April 2018, vol.1, no.1, pp.296
Elastomeric bearings, which are generally made of rubber and lamine steel, have been used actively
for about 60 years. These bearings have evolved with technology and become an important subject in civil
engineering by providing significant improvements in the earthquake performance of structures.
This study’s goal is to investigate the behaviour of elastomeric bearings under continuously impacted fatigue
loads. The first thing to do to reach that goal is to determine of shear modulus. The process of determination of
shear modulus is clarified with ASTM D4014 standard. This norm was used to determine shear modulus in this
study. Secondly, elastomeric bearings were continuously forced to make displacement equal to half of their
thickness to get information about their behavior.
Dimensions of elastomeric bearings that were used for experiments are 100 mm x 100 mm, and their thickness is
60 mm. Bearings have 4 steel and 3 rubber layers. The total thickness of rubber layers is 42 mm.
As a start, the shear modulus of elastomeric bearings was calculated according to ASTM D4014 norm. Six
successive loading and release cycles were carried out during the experiment with a deformation equal to the
bearing thickness. After result data were obtained, shear modulus was determined from the extension curve that
occurred after the sixth cycle.
In the continuation of the study, these bearings were forced to a deformation equal to half of their thickness.
1000 cycles were carried out under 0.5 Hz frequency. As a result of these deformations, the force-displacement
hysteresis loops were obtained. This shows whether the lateral stiffness of the bearings was affected by this
scenario. Axial loads were not applied to the bearings in this scenario.
The results data that were obtained shows that the stiffness of the elastomeric bearings under repeated loading is
reduced over time and the shear modulus is not stable. As a result of this study, the softening curves in the
elastomeric bearings, which depend on the number of cycles, were obtained.