RESPONSE OF PURE-FRICTION SLIDING STRUCTURES TO BIDIRECTIONAL HARMONIC GROUND MOTION

The response of structures with sliding support to bi-directional (i.e . two horizontal components) harmonic ground motion is investigated. T he frictional forces mobilized at the sliding support are assumed to h ave the ideal coulomb-friction characteristics. The coupled differenti al equations of motion of the sliding structure in two orthogonal dire ctions are solved in the incremental form using Newmark's method with iterations. The iterations are required due to dependence of the frict ional forces on the response of the system. The responses of the syste m with bi-directional interaction are compared with those without inte raction (2D idealization in two orthogonal directions) in order to inv estigate the effects of bi-directional interaction of frictional force s at the sliding supports. It has been shown that effects of bi-direct ional interaction are significant and should be included for the effec tive design of sliding structures. Further, if the effects of bi-direc tional interaction of frictional forces are neglected then the sliding base displacement will be underestimated which is crucial from the de sign point of view. In addition to harmonic ground motion the signific ant effects of bi-directional interaction are also observed for select ed real earthquake ground excitations. Copyright (C) 1996 Elsevier Sci ence Ltd.