MODELLING OF LAMINATED ELASTOMERIC PASSIVE-CONTROL BEARINGS FOR SEISMIC ANALYSIS

O. SALOMON; S. OLLER; A. BARBAT

Conferencia; 4th World Congress on Computational Mechanics; 1998

This paper presents a nite element formulation to model hiper-elastic quasi-incompressible rubber-like materials (elastomers), taking into account large displacementsand large elastic strains as well as inelastic eects. The capacity of rubber-like materials tosupport high loads in compression and large displacements in shear is the principal reasonfor its use in devices for seismic isolation. The possibility of rubber to bulge can be reducedby inserting steel layers to increase the vertical stiness of the bearing. The shear sti-ness is not altered signicantly by the presence of these layers. Energy-dissipation devicesare obtained by using high damping rubber, elastomer improved by carbon-black particles,as well as inserting a lead-plug into them. The Ogden strain energy function have beenused as the basis for the material model implemented in a total Lagrangian formulation,decomposing the strain in its deviatory and volumetric parts and condensing the pressurevariable at element level. Mooney-Rivlin and neo-Hooke strain energy functions can beused just changing the parameters of the model. The stress-strain hysteresis, which ap-pear when these devices are subjected to dynamic or quasi-static cyclic loading, have beenmodelled by frequency dependent visco-elasticity and plasticity constitutive models. Thebearings have been simulated using an equivalent single element model capable to describethe composite behaviour of the actual isolation system. The proposed model is validatedusing experimental results and it is proofed to be a powerful tool in dealing with dierentbearing.