## 1 Introduction  
Elastomeric bearings for FPSO are located at the interfaces between topside modules and support tools on the deck of the offshore platform. Their major function is to minimize the structural interactions of the two bodies. Particularly, they shall reduce the shear loads and bending moments in the module plate girders supported on the stools. These bearings are manufactured by intersecting an elastomer made of neoprene and reinforcing steel plates in the same way as for land use [1, 2]. Land elastomeric bearings are used in bridges and buildings so that they support high-frequency repetitive loads caused by earthquakes [3, 4, 5]. Unlike those land elastomeric bearings subjected to repeated loads, the offshore elastomeric bearings are to firmly support the heavy upper module from the wind load and motion of hull in various sea environments including towing, operating, and extreme conditions [6, 7, 8]. So, an offshore elastomeric bearing is larger in size and stronger in rigidity than that for land use, and it tends to have a square block shape to effectively support the translational and rotational movements of upper topside modules caused by 6 DOF (degree of freedom) hull motions (surge, sway, heave, roll, pitch, yaw) [9]. In addition, since loads vary with types of modules on the platform, offshore elastomer bearings should have adequate shear stiffness to minimize their horizontal movements while elastically supporting the vertical loads [10]. The most important item when indicating the mechanical properties of such offshore elastomeric bearings is the shear modulus, and the method of measuring this is shown in EN 1337-3 [11], a regulation related to offshore elastomeric bearings. In the previous study [12] that analyzed the effect of reinforcing plate on the stiffness of elastomer bearing, the influence of reinforcing plate was dominant on compressive stiffness and bending stiffness. It was confirmed that the height ratio to the cross-sectional area mainly is affected. In addition, according to the EN 1337-3 regulation, it can be seen that the shore hardness of the elastomer is closely related to the shear modulus of the bearing. Many experimental and numerical studies have been reported on the effect of various parameters on the mechanical behavior of elastomeric bearings [13; 14; 15; 16; 17]. [PERSON] et al. [13] performed an experimental analysis on the seismic response of three types of steel-reinforced elastomeric bearings (SREBs) used in bridges. They concluded that all SREBs they analyzed performed exceptionally well under seismic loading. [PERSON] et al. [14] conducted experiments on SREBs attached to a concrete layer on one side and bounded on the other side. They observed that shear strain increases nonlinearly with vertical load (compressive pressure). [PERSON] and [PERSON] [15] experimentally studied the ultimate state of shear failure and the friction sliding performance of SREBs in bridges. [PERSON] et al. [16] performed experimental tests on natural rubber-laminated bearings for bridges to investigate the effects of vertical load and peak acceleration of ground motion. They also performed numerical simulations using a finite element method and proposed an accurate method for calculating seismic responses of bridges with laminated bearings. Recently, [PERSON] et al. [17] investigated the effect of various parameters on the mechanical properties of SREBs under large shear deformations numerically and experimentally. In all the literature mentioned above, experimental and/or numerical studies were conducted on elastomeric bridge-bearings only. However, till now, there have been no studies on finding the shear modulus of an offshore elastic bearing by using the EN 1337-3 regulation procedure to the authors' knowledge. The reason is that the size of marine elastomer bearings is significantly larger than that for land use, and the applied load reaches thousands of tons, so experiments cannot be carried out with existing equipment.