Accidental Torsion in Buildings: Analysis versus Earthquake Motions

Abstract

A simplified analysis procedure has been developed to consider accidental torsion in building design that is rational and convenient relative to building codes. This procedure is extended and evaluated in this paper against measured accidental torsion determined from motions of 12 buildings—with nominally-symmetric plan—recorded during Northridge (1994), Loma Prieta (1989), Whittier (1987), and Upland (1990) earthquakes. The selected buildings include structures in reinforced concrete and in steel that cover a wide range of structural systems, including moment resisting frames, shear walls, braced frames, and hybrid systems. After the measured torsion is interpreted and compared to analytical estimates, it is demonstrated that this procedure is sufficiently accurate to be used in design applications.