Design of friction connections in RC structures with hybrid steel-trussed-concrete beams

In this work a feasibility study on the use of friction devices within beam-to-column joints of RC structures is conducted. The connection is made between RC columns cast in-situ and semi-prefabricated steel-concrete beams, named Hybrid Steel-Trussed-Concrete Beams (HSTCBs). Nowadays, HSTCBs are widely adopted in civil and industrial buildings and, therefore, it is required to evaluate their compliance with the capacity design criteria and their seismic energy dissipation capability. However, the design of the reinforcement of such beams usually lead to the adoption of large amount of steel within the panel zone which becomes potentially vulnerable to the effects of seismic cyclic actions and dramatically reduce the dissipation capacity of the entire structure. Therefore, the introduction of friction dampers in the HSTCB-to-column joints is investigated in order to evaluate the ability of the device in preventing the main structural elements from damage and limiting the cracking of the panel zone, thanks to the increase of the bending moment lever arm, which reduces the shear forces in the joint. The feasibility study is firstly conducted through the development of design criteria for the pre-dimensioning of the device and, successively, the proposed solution is validated through the generation of finite element models.