Effects of Torsional Coupling on Earthquake Forces in Buildings

The elastic response of torsionally coupled one-story buildings to earthquake ground motion, characterized by idealized shapes for the response spectrum, is studied. Influence of the basic system parameters on the response is investigated. The relationship between the forces— base shears and torque— in a torsionally coupled system and the base shear in a corresponding torsionally uncoupled system is established, and the effects of torsional coupling on earthquake forces are identified. Useful upper and lower bounds are presented for the base shears and torque due to simultaneous action of two horizontal components of ground motion of equal intensity.