Structural Eccentricity Evaluation in Iranian 2800 Standard (Technical Note)

This paper assesses three definitions of eccentricity employed in the description of asymmetric multistory buildings. Other definitions of static eccentricity in multistory buildings fall essentially into one of the above categories. Using the three approaches, formulae are developed to evaluate the asymmetry of shear-type buildings where the deformation is governed by the lateral and rotational rigid-floor displacements arising from the seismic design loadings. Finally by modelling three concrete buildings according to Iranian concrete code (ABA) and investigating these three definitions and comparing them, the best method for representing Iranian 2800 Standard was selected. Simple comparisons and comments on the alternative approaches are presented with the aid of these appropriate examples. This clarification of the definition of eccentricity is needed for improved understanding of the application of codified torsional design procedures. It is also a prerequisite for advanced studies of the inelastic seismic response of multistory shear buildings.