Research Articles | Challenge Journal of Structural Mechanics

Soft-story effects on the behaviour of seismically isolated buildings under near and far-fault earthquakes

Savaş Erdem, Khalid Saifullah


DOI: https://doi.org/10.20528/cjsmec.2016.12.038
View Counter: Abstract | 1278 times |, Full Article | 301 times |

Abstract


In this study, the effects of soft-story on the seismic behaviour of 3-story and 8-story isolated buildings under near and far-fault earthquakes were investigated. Four different structural models with two different 1st story height were designed: One with 1st story height of 3m and 2nd with 1st story height of 4.5m to capture soft story effect. The prototype fixed base buildings were converted to seismically isolated buildings by introducing rubber isolators at base level. Analyses were conducted by using two different isolation systems (QW7.5Tb3 and QW7.5Tb4). The modelling of conventional fixed base prototype seismically isolated buildings and their modal analyses were conducted on finite-element program SAP2000, whereas, modelling of seismically isolated buildings and nonlinear time-history analyses were conducted using 3D-BASIS program. The four accelerations records has been used for the time-history analysis. Floor accelerations, story shears and inter-story drift ratios were the key structural responses considered. The analysis results showed seismic isolations can be used as a viable mitigation method for the buildings with soft-stories under near and far-fault earthquakes. Based on the results obtained, it is interesting to note that all types of buildings whether with soft story or with typical story height show the same acceleration trend and close values (except top floor) for all types of isolation systems and earthquakes considered. In addition, both 3 and 8-story buildings suffered increase in interstory drifts beyond the limits defined UBC 97 under earthquakes containing long period pulses.


Keywords


soft-story; seismic response; seismic isolation; near and far-fault earthquakes

Full Text:

PDF

References


Alekar JN, Jain S, Murty CVR (1997). Seismic response of RC frame buildings with soft first storeys. Proceedings of Central Building Research Institute Golden Jubilee Year Conference on Natural Hazard in the Urban Habitat, New Dehli, India, 13-24.

Bayraktar A, Altunisik AC, Sevim B, Kartal ME, Turker T, Bilici Y (2009). Comparison of near-and far-fault ground motion effect on the nonlinear response of dam-resorvoir-foundation systems. Nonlinear Dynamics, 58, 655-673.

https://doi.org/10.1007/s11071-009-9508-x

Berton S, Bolander JE, Pasian A (2008). Bi-directional response of base isolated structures subjected to near-fault ground motions. Proceedings of the 14th World Conference on Earthquake Engineering, Beijing, China.

Chopra AK, Chintanapakdee C (2001). Comparing response of SDF systems to near-fault and far-fault earthquake motions in the context of spectral regions. Earthquake Engineering and Structural Dynamics, 30, 1769–1789.

https://doi.org/10.1002/eqe.92

Hejazi F, Jilani S, Noorzaei J, Chieng CY, Jaafar MS, Ali AAA (2011). Effect of soft story on structural response of high rise buildings. IOP Conference Series: Material Science Engineering, 17(1), 012034.

https://doi.org/10.1088/1757-899X/17/1/012034

Kanitkar R, Kanitkar V (2004). Seismic performance of conventional multi-story building with open ground floors for vehicular parking. The Indian Concrete Journal, 78, 99-104.

Komur MA (2015). Soft-story effects on the behaviour of fixed base and LRB base-isolated reinforced concrete buildings. Arabian Journal for Science and Engineering, 41 (2), 381-391.

https://doi.org/10.1007/s13369-015-1664-3

Lee HS, Ko DW (2007). Seismic response characteristics of high-rise RC wall buildings having different irregularities in lower stories. Journal of Engineering Structures, 29 (11), 3149– 3167.

https://doi.org/10.1016/j.engstruct.2007.02.014

Li S, Zhang F, Wang J, Alam MS, Zhang J (2016). Effects of near-fault motions and artifical pulse-type ground motions on super-span cable-stayed bridge systems. Journal of Bridge Engineering, (in press).

https://doi.org/10.1061/(ASCE)BE.1943-5592.0001008

Mastrandrea L, Piluso V (2009). Plastic design of eccentrically braced frames, II: Failure mode control. Journal of Constructional Steel Research, 65 (5), 1015-1028.

https://doi.org/10.1016/j.jcsr.2008.10.001

Pant DR, Wijeyewickrema AC (2012). Structural performance of a base-isolated reinforced concrete building subjected to seismic pounding. Earthquake Engineering and Structural Dynamics, 1709-1716.

https://doi.org/10.1002/eqe.2158

Pinarbasi S, Konstantinidis D (2007). Seismic isolation for soft storey buildings. 10th World Conference on Seismic Isolation, Energy Dissipation and Active Vibrations Control of Structures, İstanbul, Turkey.

Providakis CP (2012). Effect of supplemental damping on LRB and FPS seismic isolators under near-fault ground motions. Soil Dynamics and Earthquake Engineering, 29(1), 80-90.

https://doi.org/10.1016/j.soildyn.2008.01.012

Ribakov Y (2010). Reduction of structural response to near fault earthquakes by seismic isolation columns and variable friction dampers. Earthquake Engineering and Engineering Vibration, 9(1), 113–122.

https://doi.org/10.1007/s11803-010-9059-7

Setia S, Sharma V (2012). Seismic response of R.C.C building with soft storey. International Journal of Applied Energy, 7 (11), 1335-1339.

Tavakoli HR, Naghavi F, Goltabar AR (2014). Dynamic response of the base-fixed and isolated building frames under far- and near-fault earthquakes. Arabian Journal for Science and Engineering, 39(4), 2573-2585.

https://doi.org/10.1007/s13369-013-0891-8


Refbacks

  • There are currently no refbacks.