Seismic behaviour and design of bracing members.

In this paper, shake table tests on single-storey concentrically braced frames, which were carried out to assess existing design approaches in Eurocode 8, are described. The stiffness and resistance of the frames tested are assessed, and recommendations for estimating key response parameters are outlined. In particular, several sources of member and frame overstrength, which play an important role in seismic performance and design, are identified based on the findings from the shake table tests. The tension-based design approach largely adopted in the design is examined together with the member slenderness limits imposed on the bracing members. It is shown that the overstrength factor specified in Eurocode 8 for the design of the non-dissipating members of the structure may underestimate the actual behaviour. It is also observed that the bracing members with slenderness exceeding the codified limits demonstrated generally satisfactory performance. Despite lower energy dissipation, a higher fracture resistance, coupled with other practical and design advantages points towards a need to reassess the codified slenderness limits.