Numerical Model of Low Cost Rubber Isolators for Masonry Housing in High Seismic Regions

Housings in developing countries have often inadequate
seismic protection, particularly for masonry. People choose this type
of structure since the cost and application are relatively cheap.
Seismic protection of masonry remains an interesting issue among
researchers. In this study, we develop a low-cost seismic isolation
system for masonry using fiber reinforced elastomeric isolators. The
elastomer proposed consists of few layers of rubber pads and fiber
lamina, making it lower in cost comparing to the conventional
isolators. We present a finite element (FE) analysis to predict the
behavior of the low cost rubber isolators undergoing moderate
deformations. The FE model of the elastomer involves a hyperelastic
material property for the rubber pad. We adopt a Yeoh hyperelasticity
model and estimate its coefficients through the available experimental
data. Having the shear behavior of the elastomers, we apply that
isolation system onto small masonry housing. To attach the isolators
on the building, we model the shear behavior of the isolation system
by means of a damped nonlinear spring model. By this attempt, the
FE analysis becomes computationally inexpensive. Several ground
motion data are applied to observe its sensitivity. Roof acceleration
and tensile damage of walls become the parameters to evaluate
the performance of the isolators. In this study, a concrete damage
plasticity model is used to model masonry in the nonlinear range.
This tool is available in the standard package of Abaqus FE software.
Finally, the results show that the low-cost isolators proposed are
capable of reducing roof acceleration and damage level of masonry
housing. Through this study, we are also capable of monitoring the
shear deformation of isolators during seismic motion. It is useful to
determine whether the isolator is applicable. According to the results,
the deformations of isolators on the benchmark one story building are
relatively small.

Authors:

• Ahmad B. Habieb
• Gabriele Milani
• Tavio Tavio
• Federico Milani

Keywords:

• Masonry
• low cost elastomeric isolator
• finite element analysis
• hyperelasticity
• damped non-linear spring
• concrete damage plasticity.

References:

[1] R. P. Nanda, M. Shrikhande, and P. Agarwal, “Low-cost base-isolation
system for seismic protection of rural buildings,” Practice Periodical on
Structural Design and Construction, vol. 21, no. 1, p. 04015001, 2015.
[2] T. Boen, Yogya Earthquake 27 May 2006: Structural Damage Report.
EERI, 2006.
[3] J. M. Kelly, “Earthquake-resistant design with rubber,” 1993.
[4] A. Das, S. K. Deb, and A. Dutta, “Shake table testing of un-reinforced
brick masonry building test model isolated by u-frei,” Earthquake
Engineering & Structural Dynamics, vol. 45, no. 2, pp. 253–272, 2016.
[5] N. C. Van Engelen, P. M. Osgooei, M. J. Tait, and D. Konstantinidis,
“Experimental and finite element study on the compression properties
of modified rectangular fiber-reinforced elastomeric isolators (mr-freis),”
Engineering Structures, vol. 74, pp. 52–64, 2014.
[6] A. Turer and B. O¨ zden, “Seismic base isolation using low-cost scrap
tire pads (stp),” Materials and Structures, vol. 41, no. 5, pp. 891–908,
2008.
[7] M. Spizzuoco, A. Calabrese, and G. Serino, “Innovative low-cost
recycled rubber–fiber reinforced isolator: experimental tests and finite
element analyses,” Engineering Structures, vol. 76, pp. 99–111, 2014.
[8] H. Toopchi-Nezhad, M. J. Tait, and R. G. Drysdale, “Testing
and modeling of square carbon fiber-reinforced elastomeric seismic
isolators,” Structural Control and Health Monitoring, vol. 15, no. 6,
pp. 876–900, 2008.
[9] M. Kumar, A. S. Whittaker, and M. C. Constantinou, “An advanced
numerical model of elastomeric seismic isolation bearings,” Earthquake
Engineering & Structural Dynamics, vol. 43, no. 13, pp. 1955–1974,
2014.
[10] M. Shahzad, A. Kamran, M. Z. Siddiqui, and M. Farhan, “Mechanical
characterization and fe modelling of a hyperelastic material,” Materials
Research, vol. 18, no. 5, pp. 918–924, 2015.
[11] D. Simulia, “Abaqus 6.13 users manual,” Dassault Systems, Providence,
RI, 2013.
[12] S. Jerrams, M. Kaya, and K. Soon, “The effects of strain rate and
hardness on the material constants of nitrile rubbers,” Materials &
design, vol. 19, no. 4, pp. 157–167, 1998.
[13] A. Calabrese, M. Spizzuoco, G. Serino, G. Della Corte, and
G. Maddaloni, “Shaking table investigation of a novel, low-cost, base
isolation technology using recycled rubber,” Structural Control and
Health Monitoring, vol. 22, no. 1, pp. 107–122, 2015.
[14] H. K. Mishra, A. Igarashi, and H. Matsushima, “Finite element analysis
and experimental verification of the scrap tire rubber pad isolator,”
Bulletin of Earthquake Engineering, pp. 1–21, 2013.
[15] G. Milani and F. Milani, “Stretch–stress behavior of elastomeric seismic
isolators with different rubber materials: numerical insight,” Journal of
Engineering Mechanics, vol. 138, no. 5, pp. 416–429, 2011.
[16] T. Choudhury, G. Milani, and H. B. Kaushik, “Comprehensive numerical
approaches for the design and safety assessment of masonry buildings
retrofitted with steel bands in developing countries: The case of india,”
Construction and Building Materials, vol. 85, pp. 227–246, 2015.
[17] S. Tiberti, M. Acito, and G. Milani, “Comprehensive fe numerical
insight into finale emilia castle behavior under 2012 emilia romagna
seismic sequence: damage causes and seismic vulnerability mitigation
hypothesis,” Engineering Structures, vol. 117, pp. 397–421, 2016.