Torsion design implications from shake-table responses of an RC low-rise building model having irregularities at the ground story

Han Seon Lee, Kyung Ran Hwang

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

A 1:5 scale five-story RC building model having the irregularities of a soft/weak story and torsion at the ground story was subjected to a series of earthquake simulation tests. The test results reveal the following: The eccentricity varied from zero to infinity with the values of base shear and torque bounded by some limits. As the intensity of table excitations increased, representing earthquakes with return periods from 50 to 2500years in Korea, the range of eccentricities at the peak values in the time histories of drift and base shear decreased from approximately ±30% to within ±10% of the transverse dimension of the model. The inertial torque was resisted by both longitudinal and transverse frames, in proportion to their instantaneous rigidity. Yielding of the longitudinal frames under severe table excitations caused a substantial loss in their instantaneous torsional resistance and thereby transferred most of the large torque to the transverse frames, resulting in a significantly degraded torsional stiffness with an enlarged torsional deformation despite almost zero eccentricity. From these observations, it is clear that the eccentricity in itself cannot represent the critical torsional behaviors. To overcome this problem, the demand in torque shall be determined in a direct relationship with the base or story shear, given as an ellipse constructed with the maximum points in its principal axes located by the two adjacent torsion-dominant modal spectral values. This approach provides a simple but transparent design tool by enabling comparison between demand and supply in shear force-torque diagrams.

Original languageEnglish
Pages (from-to)907-927
Number of pages21
JournalEarthquake Engineering and Structural Dynamics
Volume44
Issue number6
DOIs
Publication statusPublished - 2015 May 1

Fingerprint

torsion
torque
Torsional stress
Torque
eccentricity
Earthquakes
earthquake
ellipse
return period
rigidity
Rigidity
stiffness
diagram
Stiffness
history
simulation

Keywords

  • Earthquake simulation test
  • Eccentricity
  • Irregular
  • RC building
  • Torsion

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Geotechnical Engineering and Engineering Geology

Cite this

@article{1d7978b39f274b0c931e53c16b70bce5,
title = "Torsion design implications from shake-table responses of an RC low-rise building model having irregularities at the ground story",
abstract = "A 1:5 scale five-story RC building model having the irregularities of a soft/weak story and torsion at the ground story was subjected to a series of earthquake simulation tests. The test results reveal the following: The eccentricity varied from zero to infinity with the values of base shear and torque bounded by some limits. As the intensity of table excitations increased, representing earthquakes with return periods from 50 to 2500years in Korea, the range of eccentricities at the peak values in the time histories of drift and base shear decreased from approximately ±30{\%} to within ±10{\%} of the transverse dimension of the model. The inertial torque was resisted by both longitudinal and transverse frames, in proportion to their instantaneous rigidity. Yielding of the longitudinal frames under severe table excitations caused a substantial loss in their instantaneous torsional resistance and thereby transferred most of the large torque to the transverse frames, resulting in a significantly degraded torsional stiffness with an enlarged torsional deformation despite almost zero eccentricity. From these observations, it is clear that the eccentricity in itself cannot represent the critical torsional behaviors. To overcome this problem, the demand in torque shall be determined in a direct relationship with the base or story shear, given as an ellipse constructed with the maximum points in its principal axes located by the two adjacent torsion-dominant modal spectral values. This approach provides a simple but transparent design tool by enabling comparison between demand and supply in shear force-torque diagrams.",
keywords = "Earthquake simulation test, Eccentricity, Irregular, RC building, Torsion",
author = "Lee, {Han Seon} and Hwang, {Kyung Ran}",
year = "2015",
month = "5",
day = "1",
doi = "10.1002/eqe.2492",
language = "English",
volume = "44",
pages = "907--927",
journal = "Earthquake Engineering and Structural Dynamics",
issn = "0098-8847",
publisher = "John Wiley and Sons Ltd",
number = "6",

}

TY - JOUR

T1 - Torsion design implications from shake-table responses of an RC low-rise building model having irregularities at the ground story

AU - Lee, Han Seon

AU - Hwang, Kyung Ran

PY - 2015/5/1

Y1 - 2015/5/1

N2 - A 1:5 scale five-story RC building model having the irregularities of a soft/weak story and torsion at the ground story was subjected to a series of earthquake simulation tests. The test results reveal the following: The eccentricity varied from zero to infinity with the values of base shear and torque bounded by some limits. As the intensity of table excitations increased, representing earthquakes with return periods from 50 to 2500years in Korea, the range of eccentricities at the peak values in the time histories of drift and base shear decreased from approximately ±30% to within ±10% of the transverse dimension of the model. The inertial torque was resisted by both longitudinal and transverse frames, in proportion to their instantaneous rigidity. Yielding of the longitudinal frames under severe table excitations caused a substantial loss in their instantaneous torsional resistance and thereby transferred most of the large torque to the transverse frames, resulting in a significantly degraded torsional stiffness with an enlarged torsional deformation despite almost zero eccentricity. From these observations, it is clear that the eccentricity in itself cannot represent the critical torsional behaviors. To overcome this problem, the demand in torque shall be determined in a direct relationship with the base or story shear, given as an ellipse constructed with the maximum points in its principal axes located by the two adjacent torsion-dominant modal spectral values. This approach provides a simple but transparent design tool by enabling comparison between demand and supply in shear force-torque diagrams.

AB - A 1:5 scale five-story RC building model having the irregularities of a soft/weak story and torsion at the ground story was subjected to a series of earthquake simulation tests. The test results reveal the following: The eccentricity varied from zero to infinity with the values of base shear and torque bounded by some limits. As the intensity of table excitations increased, representing earthquakes with return periods from 50 to 2500years in Korea, the range of eccentricities at the peak values in the time histories of drift and base shear decreased from approximately ±30% to within ±10% of the transverse dimension of the model. The inertial torque was resisted by both longitudinal and transverse frames, in proportion to their instantaneous rigidity. Yielding of the longitudinal frames under severe table excitations caused a substantial loss in their instantaneous torsional resistance and thereby transferred most of the large torque to the transverse frames, resulting in a significantly degraded torsional stiffness with an enlarged torsional deformation despite almost zero eccentricity. From these observations, it is clear that the eccentricity in itself cannot represent the critical torsional behaviors. To overcome this problem, the demand in torque shall be determined in a direct relationship with the base or story shear, given as an ellipse constructed with the maximum points in its principal axes located by the two adjacent torsion-dominant modal spectral values. This approach provides a simple but transparent design tool by enabling comparison between demand and supply in shear force-torque diagrams.

KW - Earthquake simulation test

KW - Eccentricity

KW - Irregular

KW - RC building

KW - Torsion

UR - http://www.scopus.com/inward/record.url?scp=84961323342&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84961323342&partnerID=8YFLogxK

U2 - 10.1002/eqe.2492

DO - 10.1002/eqe.2492

M3 - Article

AN - SCOPUS:84961323342

VL - 44

SP - 907

EP - 927

JO - Earthquake Engineering and Structural Dynamics

JF - Earthquake Engineering and Structural Dynamics

SN - 0098-8847

IS - 6

ER -