APPLICATION OF IMPROVED DAMAGE INDEX FOR DESIGNING OFEARTHQUAKE RESISTANT STRUCTURES

摘要

The paper presents the application of methodology for designing of earthquake resistant structures basedon damage assessment. The necessary balance among strength capacity, stiffness and ductility isdetermined to keep the damage level within prescribed limits. This procedure can be applied to determinenecessary deformation or strength capacity for which damage degree of the structure after earthquake iswithin acceptable (prescribed) limits. The improved damage index proposed in the paper is based onplastic deformation and hysteretic energy dissipation. It is obtained by modifying the well-known Park-Ang model through eliminating some of its deficiencies connected with physical meaning of damageindex. With the introduction of corrective coefficient the influence of hysteretic energy undermonotonically increasing lateral deformation is eliminated. Through this is also included the influence ofaccumulation of inelastic deformations connected with the history of cyclic deformations duringearthquake. The proposed damage index is presented in generalized form, in the function of maximumamplitudes of plastic deformations, available ductility capacity and function including cumulative damageeffects due to the dissipation of hysteretic energy. This function, besides the parameter including influenceof deterioration, depends on achieved plastic deformations during earthquake and normalized hystereticenergy, on cyclic ductility (maximum plastic excursion) and also on accumulated ductility. By introducingthis function it is possible to include not only the structural properties, but also the characteristics of theearthquake and the effects of duration of ground oscillations. The application of this design method isgiven through the analysis of a larger number of examples. The analysis of results shows that currentdesign concept in Eurocode and other seismic codes do not provide uniform risk.