Elastomeric rubber-steel insulators C.M.M. EL. ISO. HDRB
This is the simplest typology of steel-rubber isolator: it consists in a rubber pad (usually circular) reinforced with inner vulcanised steel layers, equipped with external anchor plates. C.M.M. EL.ISO. (ELastomeric ISOlators) are rubber-steel bearing devices designed to have required values of horizontal stiffness and equivalent damping, in order to provide the appropriate isolation system for the design structure.
The isolator body consists of a series of horizontal rubber layers reinforced with vulcanised steel plates: the dimensions and number of these rubber layers give to the isolators the horizontal stiffness.
The device is completed with upper and lower anchor plates equipped with suitable systems of anchoring to the external structures (pins, screws, anchor bars).
The rubber used is made of compounds provided with dissipative properties (during shear strain cycles) which give the whole device the capacity to dissipate the seismic energy.
C.M.M. has three types of certified compounds to tune the performances of EL.ISO isolators, which differ according to the value of Shore A hardness and of shear modulus G (such values directly influence the horizontal stiffness of the isolator):
The isolator body consists of a series of horizontal rubber layers reinforced with vulcanised steel plates: the dimensions and number of these rubber layers give to the isolators the horizontal stiffness.
The device is completed with upper and lower anchor plates equipped with suitable systems of anchoring to the external structures (pins, screws, anchor bars).
The rubber used is made of compounds provided with dissipative properties (during shear strain cycles) which give the whole device the capacity to dissipate the seismic energy.
C.M.M. has three types of certified compounds to tune the performances of EL.ISO isolators, which differ according to the value of Shore A hardness and of shear modulus G (such values directly influence the horizontal stiffness of the isolator):
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The damping capacity of the isolator during shear strain cycles is completely or partially provided by the specific composition of rubber compounds: for each compound the guaranteed minimum equivalent damping corresponding to a shear strain of 100% is b=15%.
Mechanical behaviour and mathematical modelling
The typical behaviour of an EL.ISO. HDRB isolator during a horizontal deformation test is shown in the following figure:
Mechanical behaviour and mathematical modelling
The typical behaviour of an EL.ISO. HDRB isolator during a horizontal deformation test is shown in the following figure:
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The horizontal load applied and the displacement are related by shear stiffness through the following formula:
Fh = kh · d Fh: horizontal load kh: horizontal shear stiffness d: horizontal displacement |
Experimental cycles of C.M.M. isolator EL.ISO. HDRB to different displacements
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