Displacement-based seismic design of braced steel structures

This paper discusses concepts and presents procedures for the development of a displacement-based seismic design methodology for chevron bracing. Both theoretically rigorous and simplified approximate methods for calculating frame displacements corresponding to significant limit states are proposed. In other words, analytical formulations are proposed for the calculation of inter-storey drift angles and associated displacements corresponding to brace buckling and the achievement of a given brace ductility demand. The aim of the displacement-based design (DBD) methodology developed is to control both elastic (pre-yield) and inelastic (post-yield) deformation modes, thus permitting control of damage distribution within the structure. The results gained from the application of the proposed methodology to a case study are then given. The structure designed was studied using dynamic time-history response analyses. The numerical results illustrate the good performance of the DBD-compliant structure which matches the performance objectives set at the design stage.