PSEUDO-DYNAMIC TESTS ON SERVICEABLE AND ROBUST STEEL FRAMES WITH THE COMBINATION OF HYSTERETIC DAMPERS AND SEMI-RIGID CONNECTIONS

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This research is to investigate earthquake response characteristics of steel frames with the combination of earthquake resisting elements and semi-rigid connections by quasi-static and dynamic loading tests, pseudo-dynamic tests and earthquake response analysis. In this research, we adopted low-yield-point steel dampers (abbreviated LYP dampers) as earthquake resisting elements and split-tees as semi-rigid connections.1. Earthquake resistant ability of steel frames with low-yield-point steel dampersAt first the results of the quasi-static and dynamic loading tests on LYP dampers show that the shear yield resistance is increased more than two times of quasi-static one. Second, a series of sub-structuring pseudo-dynamic tests on LYP damper inserted studs are performed to examine the ability to reduce seismic responses. Third, seismic monitoring are performed on a 3-story steel building model structure, the original seismic strength of which was intentionally reduced but retrofitted by th … More e damper inserted studs. And these response behaviors simulated by the pseudo-dynamic tests are used to check the validity of constitutive modeling proposed for the dampers.2. Earthquake resistant ability of semi-rigidly jointed steel frames and steel frames with the combination of LYP dampers and semi-rigid connectionsAt first the results of quasi-static loading tests on semi-rigidly jointed steel frames with varying axial load are presented that pinching effect on hysteresis loop under high axial load is different with under no axial load. Damping effect of semi-rigid parts is confirmed by sub-structuring pseudo-dynamic tests, and calculated equivalent damping factors of semi-rigid parts are up to about 1%. Second, the result of sub-structuring pseudo-dynamic tests on steel frames with the combination of LYP dampers and semi-rigid connections are presented the good performance to earthquake in comparison with completed numerical analysis considering plastic deformation capacity of beam member and brittle fracture of welded connection instead of semi-rigid connection.It is demonstrated by a series of sub-structuring pseudo-dynamic tests that a combination of semi-rigid frame and inter-story hysteretic damper creates a fairly good structural system that satisfies not only the serviceability requirement under moderate earthquakes but also the robustness requirement under unexpected severe earthquakes. Less