Effective numerical implementations of low-cost rubber seismic isolation system for masonry housing in developing countries
In developing countries, masonry is generally employed in the construction of residential buildings due to its relatively cheap cost. However, these structures are often provided with inadequate seismic protection. A low-cost base isolation aimed at decreasing the seismic vulnerability of masonry buildings is studied in this work from a numerical standpoint. The studied isolator is an unbonded fiber-reinforced elastomeric isolator (UFREI). With fewer rubber pads than conventional isolators, the proposed UFREI is a cheaper option. A 3D finite element (FE) analysis is performed to predict the behavior of the UFREI under large displacements, capturing the softening and hardening event of the isolator.
The isolation system is then implemented into a two-story masonry building prototype, where the 3D model of a single UFREI is substituted by a nonlinear spring and a damper. A full-scale time-history analysis is performed to evaluate the performance of the isolation system applied in a high-seismic region. During simulation, the inter-story drift and tensile damage of the masonry element are monitored. The results show a promising performance of the proposed isolation with favorable base displacement.
In the other section, a newly Abaqus user-element (UEL) is introduced to predict all 3D behaviors of the UFREIs, based on macroscale computation. The UEL consists of two nodes and 12 degrees of freedom, connecting the foundation to the upper structure. The validation of the UEL is performed through a detailed 3D FE simulation on an isolated rigid slab, employing four different isolators to generate torsion and rotation during seismic motion. Finally, the representative UEL decreases significantly the computational costs of the analysis with an excellent accuracy, compared to the detailed 3D model.
In the end, an experimental study on recycled rubber materials is discussed. The recycled rubber is considered here as a main substance of the UFREIs, to reduce the fabrication cost. The experiment consists of tensile test and relaxation test to characterize the hyperelastic and damping behavior of the recycled rubber. Furthermore, mechanical properties of the rubber are estimated for numerical modeling purpose.