Original and Innovative Structural Concepts for Design, Non-Linear Analysis, and Construction of Multi-Story Base Isolated Buildings

Original and Innovative Structural Concepts for Design, Non-Linear Analysis, and Construction of Multi-Story Base Isolated Buildings

Mikayel G. Melkumyan (Armenian Association for Earthquake Engineering, Armenia)
DOI: 10.4018/978-1-5225-2089-4.ch008
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Abstract

Seismic isolation of structures is becoming a more common method of providing protection from earthquake damage. Starting from 1994, 53 buildings and structures have been designed by the author of this chapter with application of base or roof isolation systems. Of these designed buildings, the total number of already constructed and retrofitted buildings has reached 45. The number of seismically isolated buildings per capita in Armenia is one of the highest in the world. Together with that seismic isolation laminated rubber-steel bearings (SILRSBs) different by their shape and dimensions, as well as by damping (low, medium and high) were designed and about 5000 SILRSBs were manufactured in the country, tested locally and applied in construction. since 2003 seismic isolation technologies were designed and then extensively applied in construction of multi-story buildings. these are: base isolated residential complexes, business centers, hotels, schools, and hospital buildings. Original and innovative structural concepts, including the new approach on installation of seismic isolation rubber bearings by clusters, were developed and designed for construction of these base isolated buildings and they are described in the given chapter. The advantages of this approach are listed and illustrated by the examples. It is mentioned that suggested new structural solutions in seismic isolation are bringing to significant savings in construction cost. The earthquake response comparative analyses were carried out for some of the considered buildings in two versions (i.e., when the buildings are base isolated and when they are fixed base). Several histories were used in the analyses and for both cases the buildings were analyzed also according to the requirements of the Armenian Seismic Code. Comparison of the obtained results indicates the high effectiveness of the proposed structural concepts of isolation systems and the need for further improvement of the Seismic Code provisions regarding the values of the reduction factors. A separate section in the chapter dedicated to the design of high damping laminated rubber-steel bearings and to results of their tests.
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1. Introduction

The mentioned in the Abstract number of buildings where seismic isolation systems were successfully implemented during a period of the last 21 years is illustrated in Figure 1. Among these buildings there were:

  • Bath-houses,

  • Private residences,

  • School buildings,

  • Clinic and hospital buildings,

  • Business centers,

  • Hotels, and

  • Apartment buildings.

Actually more than two buildings per year in average with seismic isolation systems were constructed or retrofitted in Armenia. Also the mentioned above great number of manufactured in the country SILRSBs is illustrated in Figure 2.

Figure 1.

Number of base and roof isolated buildings newly constructed or retrofitted in Armenia by years

Figure 2.

Number of rubber bearings installed in the newly constructed or retrofitted buildings in Armenia by years

Success in implementation of seismic isolation became possible due to applied significant efforts by the author of this chapter, his permanent struggle and overcoming of the invisible barriers caused by envious and conservative community of so called “scientists/engineers”.

It should be mentioned that seismic isolation in the country initially (1994-2001) developed mainly through the projects financed by international institutions (World Bank, UNIDO, Huntsman Corporation, Caritas Switzerland). However, the advantages of seismic isolation were so obvious that in the subsequent years great interest in application of this technology has been shown by private companies and even by the Government of Armenia. Therefore, further development of seismic isolation continued (2002-2016) through the projects financed by the Hayastan All-Armenian Fund, private companies such as PCG International, LLC (USA), Elite Group, CJSC (Armenia), Tufenkian Hospitality, LLC (Armenia), ITARCO Construction CJSC (Armenia) as well as individuals who constructed their own houses and also by the governmental program for providing apartments for young families. Given the local manufacturing of different types of rubber bearings, the developed seismic isolation techniques lead to significant savings in construction costs. Construction of ordinary (apartment) buildings and critical facilities (schools, hospitals, etc.) using seismic isolation costs 30-35% cheaper in comparison with the conventionally designed buildings. These facts attract the attention of the international professional community, of different institutions and private investors (The World Bank Implementation Completion Report 1997). Many experts in the field started to stress and underline the achieved progress. As it is mentioned in Martelli et al.(2001):

…the number of new applications of innovative anti-seismic techniques, especially seismic isolation, is particularly large in Japan, P.R. China and Armenia. Some other countries are beginning to follow the excellent example of Armenia where seismic isolators are locally manufactured also for foreign markets. An existing bank building at Irkutsk-City in Russia was retrofitted by applying the technology invented by Prof. Melkumyan in Armenia.

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