SEISMIC TORSIONAL EFFECTS ON BUILDINGS.

Abstract

The paper gives the background to the seismic torsional provisions of the New Zealand NZS 4203 ″Code of Practice for General Structural Design and Design Loadings″ . These provisions attempt to deal with three effects: accidental eeccentricity, torsional ground motion, and coupling between torsional and translational modes. The first two effects lead to an effective eccentricity of one-tenth of the width of a building, while the third leads to a parabolic function of the calculated eccentricity: this was obtained by applying existing results for torsional amplification to a number of typical building structures.