Does ETABS amplify accidental torsional eccentricity by 1.5, as required by IS:1893?

Answer: ETABS does not automatically amplify accidental torsion. Dynamic analysis need not amplify the accidental torsion which results from eccentric application of lateral earthquake loading. For static analysis, accidental torsional eccentricity may be amplified manually through the following process:

• Compute geometric eccentricity by locating the centers of mass and rotation within a story.

• Locate the coordinate where enhanced eccentricity will be defined.

• Define an additional lateral load case of QUAKE type. Use only the User Load options, then in the dialog box, use the coordinate calculated as the point of load application, and enter the value of story shear.