Pseudo-dynamic testing of a 3D full-scale high ductile steel-concrete composite MR frame structure at ELSA

Composite moment resisting (MR) frame structures consisting of steel-concrete beams and reinforced concrete partially encased columns can provide efficient and economical alternatives to traditional steel or reinforced concrete constructions. In addition to economies achieved by effective use of different materials, this research shows the feasibility of composite MR frames with partially encased columns and partial strength beam-to-column joints to provide strength and ductility exceeding that in conventional steel or reinforced concrete MR frame structures. In detail, energy dissipation is concentrated both in column web panels which are not surrounded by concrete and in composite beam-to-column connections. A full-scale two-storey composite building was used to validate the system performance of composite MR frames with partial strength joints. The frame structure was subjected to pseudo-dynamic (PsD) tests at the European Laboratory for Structural Assessment (ELSA) of Joint Research Centre (JRC), in order to simulate the structural response under ground motions corresponding to earthquake hazards for a highseismicity site with 10 % and 2 % chance of exceedence in 10 years. The ground motion for 10 % chance of exceedence in 10 years earthquake hazard caused minor damage while the one for 2 % chance of exceedence in 10 years earthquake hazard entailed column web panel yielding, connection yielding and plastic hinging at column base joints. An earthquake level chosen to approach the collapse limit state induced more damage and was accompanied by further column web panel yielding, connection yielding and inelastic phenomena at column base joints without local buckling. Successively, the structure was subjected to a final quasi-static cyclic test with interstorey drift ratios up to 4.6 %. Extensive cracks in the slabs and failure of extended end plates at weld toes were observed. Moreover, test offered additional opportunities to examine construction methods and validate the performance of simulation FE models. Exploiting inelastic static pushover and time-history analysis procedures, behaviour factors, design overstrength factors and the ductility demand of the structure was estimated. Finally, behaviour factors and overstrength factors were identified and compared to code-specified assumptions.