Design of innovative friction damper devices for earthquake-resilient RC frames with Hybrid Steel-Trussed Concrete Beams

This thesis focuses on the design of innovative friction damper devices for earthquake-resilient Reinforced Concrete (RC) frames realized with Hybrid Steel-Trussed Concrete Beams (HSTCBs). These devices fall within the framework of the recently-proposed low-damage design strategy for structures built in earthquake-prone areas, on the basis of which the structures are designed to experience negligible damage when subjected to seismic events. The comprehensive solution proposed aims at introducing a feasible option for building earthquake-resilient RC Moment Resisting Frames (MRFs), having been proposed very few solutions for this structural scheme so far. Innovative solutions are proposed for both Beam-to-Column (BCC) and Column-to-Foundation (CFC) connections. For each connection, an analytical design procedure is proposed, and a 3D FEM model is developed and tested. The capability of the proposed connections in ensuring earthquake-resilient RC frames is assessed by comparing the seismic performance of traditional and innovative RC frames realized with HSTCBs. As a background to research on dissipative friction connections for MRFs with HSTC beams, two issues affecting the latter structural typology are investigated, namely shear capacity assessment and mechanical performance of HSTCB-column joints. With regard to the former issue, a design-oriented analytical model based on the truss mechanism with variable inclination of the concrete strut is proposed. Concerning the other issue, an approach is derived for the application, in FE software packages, of an-already-existing macro model developed to simulate the cyclic behavior of RC beam-column joints, extending it to the case of HSTC beams.