Techno Press
Techno Press

Earthquakes and Structures   Volume 15, Number 6, December 2018, pages 639-654
DOI: http://dx.doi.org/10.12989/eas.2018.15.6.639
 
Mushroom skeleton to create rocking motion in low-rise steel buildings to improve their seismic performance
Vahid Mahdavi, Mahmood Hosseini and Alireza Gharighoran

 
Abstract     [Full Text]
    Rocking motion have been used for achieving the \'resilient buildings\' against earthquakes in recent studies. Lowrise buildings, unlike the tall ones, because of their small aspect ratio tend to slide rather than move in rocking mode. However, since rocking is more effective in seismic response reduction than sliding, it is desired to create rocking motion in low-rise buildings too. One way for this purpose is making the building\'s structure rock on its internal bay(s) by reducing the number of bays at the lower part of the building\'s skeleton, giving it a mushroom form. In this study \'mushroom skeleton\' has been used for creating multi-story rocking regular steel buildings with square plan to rock on its one-by-one bay central lowest story. To show if this idea is effective, a set of mushroom buildings have been considered, and their seismic responses have been compared with those of their conventional counterparts, designed based on a conventional code. Also, a set of similar buildings with skeleton stronger than code requirement, to have immediate occupancy (IO) performance level, have been considered for comparison. Seismic responses, obtained by nonlinear time history analyses, using scaled three-dimensional accelerograms of selected earthquakes, show that by using appropriate \'mushroom skeleton\' the seismic performance of buildings is upgraded to mostly IO level, while all of the conventional buildings experience collapse prevention (CP) level or beyond. The strong-skeleton buildings mostly present IO performance level as well, however, their base shear and absolute acceleration responses are much higher than the mushroom buildings.
 
Key Words
    resilient building; directed-damage design; mushroom skeleton; energy dissipators; seismic performance level; nonlinear time history analyses
 
Address
Vahid Mahdavi: Department of Civil Engineering, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran
Mahmood Hosseini: Structural Engineering Research Center, International Institute of Earthquake Engineering and Seismology (IIEES),Tehran, Iran
Alireza Gharighoran: Faculty of Civil and Transportation Engineering, University of Isfahan, Isfahan, Iran
 

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