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Earthquakes and Structures
  Volume 9, Number 3, September 2015 , pages 603-623
DOI: https://doi.org/10.12989/eas.2015.9.3.603
 


Retrofitting of vulnerable RC structures by base isolation technique
A. B. M. Saiful Islam, Mohd Zamin Jumaat, Rasel Ahmmad and Kh. Mahfuz ud Darain

 
Abstract
    The scale and nature of the recent earthquakes in the world and the related earthquake disaster index coerce the concerned community to become anxious about it. Therefore, it is crucial that seismic lateral load effect will be appropriately considered in structural design. Application of seismic isolation system stands as a consistent alternative against this hazard. The objective of the study is to evaluate the structural and economic feasibility of reinforced concrete (RC) buildings with base isolation located in medium risk seismic region. Linear and nonlinear dynamic analyses as well as linear static analysis under site-specific bi-directional seismic excitation have been carried out for both fixed based (FB) and base isolated (BI) buildings in the present study. The superstructure and base of buildings are modeled in a 3D finite element model by consistent mass approach having six degrees of freedom at each node. The floor slabs are simulated as rigid diaphragms. Lead rubber bearing (LRB) and High damping rubber bearing (HDRB) are used as isolation device. Change of structural behaviors and savings in construction costing are evaluated. The study shows that for low to medium rise buildings, isolators can reduce muscular amount of base shears, base moments and floor accelerations for building at soft to medium stiff soil. Allowable higher horizontal displacement induces structural flexibility. Though incorporating isolator increases the outlay, overall structural cost may be reduced. The application of base isolation system confirms a potential to be used as a viable solution in economic building design.
 
Key Words
    aseismic building; base isolation; nonlinear dynamics; linear dynamic analysis; seismic excitation; structural insinuation; economic insin
 
Address
A. B. M. Saiful Islam, Mohd Zamin Jumaat, Rasel Ahmmad and Kh. Mahfuz ud Darain: Department of Civil Engineering, University of Malaya, Kuala Lumpur, Malaysia

Kh. Mahfuz ud Darain: Architecture discipline, Khulna University, Khulna, Bangladesh
 

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