Tests and model calibration of high-strength steel tubular beam-to-column and column-base composite joints for moment-resisting structures

Performance-based engineering (PBE) methodologies allow for the design of more reliable earthquakeresistant structures. Nonetheless, to implement PBE techniques, accurate finite element models of critical components are needed. With these objectives in mind, initially, we describe an experimental study on the seismic behaviour of both beam-to-column (BTC) and column-base (CB) joints made of high-strength steel S590 circular columns filled with concrete. These joints belonged to moment-resisting frames (MRFs) that constituted the lateral-force-resisting system of an office building. BTC joints were conceived as rigid and of partial strength, whereas CB joints were designed as rigid and of full strength. Tests on a BTC joint composed of an S275 steel composite beam and high-strength steel concrete-filled tubes were carried out. Moreover, two seismic CB joints were tested with stiffeners welded to the base plate and anchor bolts embedded in the concrete foundation as well as where part of a column was embedded in the foundation with no stiffeners. A test programme was carried out with the aim of characterising these joints under monotonic, cyclic and random loads. Experimental results are presented by means of both force–interstory drift ratio and moment–rotation relationships. The outcomes demonstrated the adequacy of these joints to be used for MRFs of medium ductility class located in zones of moderate seismic hazard. Then, a numerical calibration of the whole joint subassemblies was successfully accomplished. Finally, non-linear time-history analyses performed on 2D MRFs provided useful information on the seismic behaviour of relevant MRFs.