INELASTIC BEHAVIOR OF STEEL FRAMES WITH ADDED VISCOELASTIC DAMPERS

This paper presents the results of shaking table studies on the inelas tic behavior oi two identical 2/5-scale three-story steel structures, one with and the other without viscoelastic (VE) dampers. The VE dampe rs were designed to provide the test structure with 8% and 15% critica l damping ratios, respectively, at an ambient temperature of 28 degree s C. Test results show that the VE dampers were effective in reducing the overall response and ductility demand on the test, structure under strong earthquake ground motions, The structure with dampers sustaine d much stronger earthquake ground motions and experienced less damage than did the structure without dampers. During the tests, the VE dampe rs experienced large shear strains far beyond their design value of 60 % strain and the usual design limit such as 100% strain. Analytical re sults show that damping ratios of the viscoelastically damped structur e can be accurately predicted by the modal strain energy method. The i nelastic seismic response can also be well described-by using bilinear elements for the structural members. Results from this study suggest that a viscoelastically damped structure with sufficiently large dampi ng may remain elastic under strong earthquake ground motions.