An evaluation of the inelastic response of systems under biaxial seismic excitations

A more realistic evaluation of the effects of earthquakes on building structures should account for the contemporaneous action of the two horizontal components of the ground motion. In this paper, the effects of biaxial seismic excitations are evaluated by analysing the inelastic response of a hysteretic model having an elliptical yield domain subjected to two-component real and artificial earthquakes. Increments in damage due to the biaxiality of the seismic input are estimated as the system stiffness configuration and the experienced level of inelasticity vary. The increase in strength needed under biaxial excitation to reduce the values of the damage parameters to those accepted under uniaxial excitation is evaluated in order to provide design recommendations.