The principal aims of this research thesis were to assess the degree of improvement in performance achieved through the use of energy dissipative devices in the design of steel frame structures under seismic loading.
The first part of the research reports on a series of monotonic and cyclic tests performed on the energy dissipative device mounted in a single-storey, planar K-braced frame. The device consists of a short length of square hollow section with a diaphragm plate of thickness either 2mm or 3mm welded inside it. It is installed between the bracing and the top member of the braced frame, with the diaphragm lying in the plane of the frame, so that it is loaded in pure shear as the frame undergoes lateral deformation.
The devices can be easily fitted, remove and replace. In addition, the devices are cheap to manufacture. All the devices which were tested yielded at very low deformations and sustained very large ductility without failure. From the cyclic test results, it is shown that a device with 3mm is recommended as offering the best combination of dissipative capacity and robustness.
For the second part of the research, an extensive analysis of 10-storey frames, both undamped moment-resisting frames and retrofitted with energy dissipative devices has been performed. This 10-storey building was modeled using the finite element program Strand 7 and was analyzed using linear time history analysis and non-linear static analysis. Upon comparison of the analysis, it was found that the dissipative system lead to a substantial improvement in frame performance, in terms of plastic hinge formation and deformations.
Therefore it is concluded that these devices offer a simple, cheap and robust way of dissipating significant amounts of energy in seismically loaded frames.