A Comparative Study of Torsionally Unbalanced Multi-Storey Structures under Seismic Loading


Abstract: After a short review of the torsional irregularity requirements of the new Turkish Earthquake Code (TEC'97), a parametric study is carried out on various ten-storey shear-wall frames with rather high torsional irregularities. The internal member forces are computed and compared in the solutions with 5% accidental eccentricity and with increased eccentricities, under seismic loading, according to TEC'97. Torsional amplification factors are introduced and calculated along the height of the buildings. The numerical solutions of the investigated buildings show that the maximum increase in the bending moments at the most critical beams and columns is about 10%. The torsional irregularity coefficients of the sample structures evaluated according to Uniform Building Code'97 and TEC'97 are also compared in the study, the computations of which are based on absolute and relative displacements, respectively. The UBC'97 coefficients are rather high with respect to the TEC'97 values.

Keywords: Torsional irregularity, Seismic design, Seismic Codes, Asymmetric buildings, Irregular structures.

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