- Volume 9 Issue 1
DOI QR Code
Ratio of Torsion (ROT): An index for assessing the global induced torsion in plan irregular buildings
- Stathi, Chrysanthi G. (Institute of Structural Analysis & Antiseismic Research Department of Structural Engineering, School of Civil Engineering, National Technical University) ;
- Bakas, Nikolaos P. (Institute of Structural Analysis & Antiseismic Research Department of Structural Engineering, School of Civil Engineering, National Technical University) ;
- Lagaros, Nikos D. (Institute of Structural Analysis & Antiseismic Research Department of Structural Engineering, School of Civil Engineering, National Technical University) ;
- Papadrakakis, Manolis (Institute of Structural Analysis & Antiseismic Research Department of Structural Engineering, School of Civil Engineering, National Technical University)
- Received : 2014.07.14
- Accepted : 2015.04.06
- Published : 2015.07.25
Due to earthquakes, many structures suffered extensive damages that were attributed to the torsional effect caused by mass, stiffness or strength eccentricity. Due to this type of asymmetry torsional moments are generated that are imposed by means of additional shear forces developed at the vertical resisting structural elements of the buildings. Although the torsional effect on the response of reinforced concrete buildings was the subject of extensive research over the last decades, a quantitative index measuring the amplification of the shear forces developed at the vertical resisting elements due to lateral-torsional coupling valid for both elastic and elastoplastic response states is still missing. In this study a reliable index capable of assessing the torsional effect is proposed. The performance of the proposed index is evaluated and its correlation with structural response quantities like displacements, interstorey drift, base torque, shear forces and upper diaphragm's rotation is presented. Torsionally stiff, mass eccentric single-story and multistory structures, subjected to bidirectional excitation, are considered and nonlinear dynamic analyses are performed using natural records selected for three hazard levels. It was found that the proposed index provides reliable prediction of the magnitude of torsional effect for all test examples considered.
torsional effect;mass eccentric;torsionally stiff;center of rigidity;nonlinear dynamic analyses
Supported by : European Research Council
- Anagnostopoulos, S.A., Alexopoulou, Ch. and Stathopoulos, K.G. (2010), "An answer to an important controversy and the need for caution when using simple models to predict inelastic earthquake response of buildings with torsion", Earthq. Eng. Struct. Dyn., 39(5), 521-540. https://doi.org/10.1002/eqe.957
- Anagnostopoulos, S.A., Kyrkos, M.T. and Stathopoulos, K.G. (2015), "Earthquake induced torsion in buildings: critical review and state of the art", Earthq. Struct., 8(2), 305-377. https://doi.org/10.12989/eas.2015.8.2.305
- Bosco, M., Ferrara, G.A.F., Ghersi, A., Marino, E.M. and Rossi, P.P. (2015), "Seismic assessment of existing r.c. framed structures with in-plan irregularity by nonlinear static methods", Earthq. Struct., 8(2), 401-422. https://doi.org/10.12989/eas.2015.8.2.401
- Bosco, M., Marino, E.M. and Rossi, P.P. (2013), "An analytical method for the evaluation of the in-plan irregularity of non-regularly asymmetric buildings", Bull. Earthq. Eng., 11(5), 1423-1445. https://doi.org/10.1007/s10518-013-9438-3
- Chandler, A.M. and Duan, X.N. (1997), "Performance of asymmetric code-designed buildings for serviceability and ultimate limit states", Earthq. Eng. Struct. Dyn., 26(7), 717-736. https://doi.org/10.1002/(SICI)1096-9845(199707)26:7<717::AID-EQE672>3.0.CO;2-X
- Chandler, A.M., Duan, X.N. and Rutenberg, A. (1996), "Seismic torsional response: assumptions, controversies and research progress", Eur. Earthq. Eng., 10(1), 37-51.
- Cheung, V.W.-T. and Tso, W.K. (1986), "Eccentricity in irregular multistory buildings", Can. J. Civ. Eng., 13(1), 46-52. https://doi.org/10.1139/l86-007
- Chopra, A.K. and Goel, R.K. (1991), "Evaluation of torsional provisions in seismic codes", J. Struct. Eng., 117(12), 3762-3782. https://doi.org/10.1061/(ASCE)0733-9445(1991)117:12(3762)
- De La Colina, J. (1999), "Effects of torsion factors on simple non-linear systems using fully bidirectional analyses", Earthq. Eng. Struct. Dyn., 28(7), 691-706. https://doi.org/10.1002/(SICI)1096-9845(199907)28:7<691::AID-EQE834>3.0.CO;2-U
- De La Llera, J.C. and Chopra, A.K. (1995), "A simplified model for analysis and design of asymmetric plan buildings", Earthq. Eng. Struct. Dyn., 24(4), 573-594. https://doi.org/10.1002/eqe.4290240408
- De La Llera, J.C. and Chopra, A.K. (1995), "Understanding the inelastic seismic behaviour of asymmetric plan buildings", Earthq. Eng. Struct. Dyn., 24(4), 549-572. https://doi.org/10.1002/eqe.4290240407
- EC8-Eurocode 8 (2004), Design provisions for earthquake resistance of structures, European StandardEN1998-1.
- Fragiadakis, M. and Papadrakakis, M. (2008), "Modelling, analysis and reliability of seismically excited structures: Computational issues", Int. J. Comput. Meth., 5(4), 483-511. https://doi.org/10.1142/S0219876208001674
- Georgoussis, G.K. (2014), "Modified seismic analysis of multistory asymmetric elastic buildings and suggestions for minimizing the rotational response", Earthq. Struct., 7(1), 39-55. https://doi.org/10.12989/eas.2014.7.1.039
- Humar, J. and Kumar, P. (1998), "A new look at torsion design provisions in seismic building codes", 12th World Conference on Earthquake Engineering.
- Humar, J.L. (1984), "Design for seismic torsional forces", Can. J. Civ. Eng., 11(2), 150-163. https://doi.org/10.1139/l84-027
- Jeong, S.-H. and Elnashai, A.S. (2005), "Analytical assessment of an irregular RC frame for full-scale 3D pseudo-dynamic testing part I: Analytical model verification", J. Earthq. Eng., 9(1), 95-128. https://doi.org/10.1080/13632460509350535
- Karimiyan, S., Moghadam, A.S., Karimiyan, M. and Kashan, A.H. (2013), "Seismic collapse propagation in 6-story RC regular and irregular buildings", Earthq. Struct., 5(6), 753-779. https://doi.org/10.12989/eas.2013.5.6.753
- Kent, D.C. and Park, R. (1971), "Flexural members with confined concrete", J. Struct. Div., 97(7), 1969-1990.
- Kyrkos, M.T. and Anagnostopoulos, S.A. (2011a), "An assessment of code designed, torsionally stiff, asymmetric steel buildings under strong earthquake excitations", Earthq. Struct., 2(2), 109-126. https://doi.org/10.12989/eas.2011.2.2.109
- Kyrkos, M.T. and Anagnostopoulos, S.A. (2011b), "Improved earthquake resistant design of torsionally stiff asymmetric steel buildings", Earthq. Struct., 2(2), 127-147. https://doi.org/10.12989/eas.2011.2.2.127
- Kyrkos, T.M. and Anagnostopoulos, A.S. (2013), "Improved earthquake resistant design of eccentric steel buildings", Soil Dyn. Earthq. Eng., 47, 144-156. https://doi.org/10.1016/j.soildyn.2012.07.011
- Lagaros, N.D., Papadrakakis, M. and Bakas, N. (2006), "Automatic minimization of the rigidity eccentricity of 3D reinforced concrete buildings", J. Earthq. Eng., 10(3), 1-32.
- Lucchini, A., Monti, G. and Kunnath, S. (2009), "Seismic behavior of single-storey asymmetric-plan buildings under uniaxial excitation", Earthq. Eng. Struct. Dyn., 38(9), 1053-1070. https://doi.org/10.1002/eqe.881
- Makarios, T. (2008), "Practical calculation of the torsional stiffness radius of multi-storey tall buildings", Struct. Des. Tall Spec. Build., 17(1), 39-65. https://doi.org/10.1002/tal.316
- Makarios, T. and Anastassiadis, A. (1998a), "Real and fictitious elastic axes of multi-storey buildings: theory", Struct. Des. Tall Spec. Build., 7(1), 33-55. https://doi.org/10.1002/(SICI)1099-1794(199803)7:1<33::AID-TAL95>3.0.CO;2-D
- Makarios, T. and Anastassiadis, A. (1998b), "Real and fictitious elastic axes of multi-storey buildings: applications", Struct. Des. Tall Spec. Build., 7(1), 57-71. https://doi.org/10.1002/(SICI)1099-1794(199803)7:1<57::AID-TAL96>3.0.CO;2-0
- Marino, E.M. and Rossi, P.P. (2004), "Exact evaluation of the location of the optimum torsion axis", Struct. Des. Tall Spec. Build, 13(4), 277-290. https://doi.org/10.1002/tal.252
- Marusic, D. and Fajfar, P. (2005), "On the inelastic seismic response of asymmetric buildings under bi-axial excitation", Earthq. Eng. Struct. Dyn., 34(8), 943-963. https://doi.org/10.1002/eqe.463
- McKenna, F. and Fenves, G.L. (2001), The OpenSees Command Language Manual - Version 1.2, Pacific Earthquake Engineering Research Centre, University of California, Berkeley.
- Myslimaj, B. and Tso, W.K. (2005), "A Design-oriented approach to strength distribution in single-story asymmetric systems with elements having strength dependent stiffness", Earthq. Spectra, 21(1), 197-212. https://doi.org/10.1193/1.1854152
- Myslimaj, B. and Tso, W.K. (2002), "A strength distribution criterion for minimizing torsional response of asymmetric wall-type systems", Earthq. Eng. Struct. Dyn., 31(1), 99-120. https://doi.org/10.1002/eqe.100
- Palermo, M., Silvestri, S., Gasparini, G. and Trombetti, T. (2013), "Physically-based prediction of the maximum corner displacement magnification of one-storey eccentric systems", Bull. Earthq. Eng., 11(5), 1467-1491. https://doi.org/10.1007/s10518-013-9445-4
- Papachristidis, A., Fragiadakis, M. and Papadrakakis, M. (2010), "A 3D fiber beam-column element with shear modeling for the inelastic analysis of steel structures", Comput. Mech., 45(6), 553-572. https://doi.org/10.1007/s00466-010-0470-8
- Papazachos, B.C., Papaioannou, Ch.A. and Theodulidis, N.P. (1993), "Regionalization of seismic hazard in Greece based on seismic sources", Nat. Hazards, 8(1), 1-18. https://doi.org/10.1007/BF00596232
- Paulay, T. (1997), "Displacement-based design approach to earthquake induced torsion in ductile buildings", Eng. Struct., 9(9), 699-707.
- Paulay, T. (1998), "Torsional mechanisms in ductile building systems", Earthq. Eng. Struct. Dyn., 27(10), 1101-1121. https://doi.org/10.1002/(SICI)1096-9845(199810)27:10<1101::AID-EQE773>3.0.CO;2-9
- Perus, I. and Fajfar, P. (2005), "On the inelastic torsional response of single-storey structures under bi-axial excitation", Earthq. Eng. Struct. Dyn., 34(8), 931-941. https://doi.org/10.1002/eqe.462
- Poole, R.A. (1977), "Analysis for torsion employing provisions of NZRS 4203", Bull. NZ. Soc. Earthq. Eng., 10(4), 219-225.
- Reem, H. and Chopra, A.K. (1987), Earthquake Response of Torsionally-Coupled Buildings, Earthquake Engineering Research Centre, College of Engineering, University of California at Berkeley.
- Riddel, R. and Vasquez, J. (1984), "Existence of centres of resistance and torsional uncoupling of earthquake response of buildings", Proceedings of 8thWorld Conference on Earthquake Engineering, 4, 187-194.
- Rutenberg, A. (2002), "EAEE Task Group (TG) 8: Behaviour of irregular and complex structures-progress since 1998", Proceedings of the 12th European Conference in Earthquake Engineering, London.
- Scott, B.D., Park, R. and Priestley, M.J.N. (1982), "Stress-Strain behavior of concrete confined by overlapping hoops at low and high strain rates", ACI J., 79, 13-27.
- Smith, B.S. and Vezina, S. (1985), "Evaluation of centers of resistance in multistorey building structures", Proceedings Of Institution Of Civil Engineers, Part 2, Institution of Civil Engineers, 79(4), 623-635. https://doi.org/10.1680/iicep.1985.761
- Somerville, P. and Collins, N. (2002), "Ground motion time histories for the Humboldt bay bridge", Pasadena, CA, URS Corporation.
- Stathi, Ch.G. (2014), "Optimum design of earthquake resistant structures implementing computational methods", Ph.D. Dissertation, NTUA, Athens, Greece.
- Stathopoulos, K.G. and Anagnostopoulos, S.A. (2003), "Inelastic earthquake response of single-story asymmetric buildings: an assessment of simplified shear-beam models", Earthq. Eng. Struct. Dyn., 32(12), 1813-1831. https://doi.org/10.1002/eqe.302
- Trombetti, T.L. and Conte, J.P. (2005), "New insight into and simplified approach to seismic analysis of torsionally coupled one-story, elastic systems", J. Sound Vib., 286(1), 265-312. https://doi.org/10.1016/j.jsv.2004.10.021
- Tso, W.K. (1990), "Static eccentricity concept for torsional moments estimations", J. Struct. Eng., 116(5), 1199-1212. https://doi.org/10.1061/(ASCE)0733-9445(1990)116:5(1199)
- Design aspects for minimizing the rotational behavior of setbacks buildings vol.10, pp.5, 2016, https://doi.org/10.12989/eas.2016.10.5.1049
- Evaluating contradictory relationship between floor rotation and torsional irregularity coefficient under varying orientations of ground motion vol.11, pp.6, 2016, https://doi.org/10.12989/eas.2016.11.6.1027