Dual-Steel Eccentrically Braced Frames with Bolted Links – Simulation of Safe Removal Process

Current seismic design philosophy is based on dissipative structural response, which implicitly accepts damage to the main structure and significant economic losses. Repair of the structure is often impeded by the permanent (residual) drifts of the structure. The proposed research aims at reducing the repair costs and downtime of a structure hit by an earthquake, and consequently more rational design approach in the context of sustainability. These objectives are to be attained through removable dissipative members and re-centring capability of the structure, concepts that are to be implemented in a dual structure, obtained by combining steel eccentrically braced frames with removable bolted links with moment resisting frames. The bolted links are intended to provide the energy dissipation capacity and to be easily replaceable, while the more flexible moment resisting frames would provide the necessary re-centring capability to the structure. The columns of the structure are to be realised from high strength steel, in order to keep these members in the elastic range even under strong seismic input. Practical solutions regarding order in which bolted links need to be replaced are proposed. In order that the link removal process to be a safe one, there is analyzed and chosen a solution that uses tension rods with viscous dampers mounted on the structure during link removal. Once the seismic link is removed from the structure, this system slowly releases the accumulated forces and the structure comes back to its initial position.