Efficiency of low-rise steel rocking frames founded on conventional and rocking foundations

• The performance of steel rocking frames is explored, using a 3-storey building as an example.
• Three design alternatives are compared, using a conventional steel-braced frame as reference.
• Rocking at the base-plate level is compared to foundation rocking, along with a hybrid solution.
• The finite element method is employed, accounting for geometric and material nonlinearities.
• Models are validated against published experimental results, thus offering credible insights.

Steel rocking frames have been proposed as an alternative to steel-braced frames, aiming to reduce seismic damage. Energy dissipation members, such as yielding base plates and “butterfly” fuses are introduced, while the restoring forces are provided by self-weight and post-tensioned cables. Rocking is constrained within the superstructure, with uplifting taking place at the base-plate level. An alternative is to allow rocking at the foundation level, simply by under-sizing the foundation. This paper explores the efficiency of such design alternatives, using a 3-storey building as an example. Three alternatives are compared, using a steel-braced frame as reference. The performance of a Base Plate Rocking Structure is compared to that of a Foundation Rocking Structure, along with a hybrid solution combining both mechanisms. The study is performed employing the finite element method, accounting for geometric and material nonlinearities. The models are validated against published experimental results, thus offering credible insights.