FRICTION DISSIPATIVE DEVICES FOR MITIGATING SEISMIC VULNERABILITY IN REINFORCED CONCRETE FRAMES

This thesis explores the application of friction-dissipative devices in Reinforced Concrete (RC) structures to mitigate seismic vulnerability. The research mainly focuses on designing and testing a friction dissipative device for a Hybrid Steel Trussed Concrete Beam (HSTCB) to RC column connection for new RC Moment Resisting Frames (MRFs).HSTCBs have been used in buildings for the last 30 years. Still, despite their functionality, they are vulnerable to seismic activity, especially in the beam-to-column connection due to the large amount of reinforcement in that zone. To mitigate it, some structural modifications are proposed for the HSTCB and device connection.A uniaxial friction-dissipative device is designed and tested to choose the appropriate friction materials for sliding surfaces, assess the application of bolt preload, and explore the effectiveness of disc spring in mitigating the variation of bolt load during sliding. These are key issues in determining the behavior of the HSTCB to RC column dissipative connection.Thus, the appropriate use of HSTCB to RC column dissipative connection for mitigating the seismic vulnerability of MRFs is investigated. To this aim, a literature review on the use of friction-dissipative devices for beam-to-column connection is also discussed in detail. The hybrid steel trussed concrete beam to the reinforced concrete column connection is analyzed in detail, providing some modification to the design of the friction dissipative connection proposed in previous research.FEM analyses are performed on the uniaxial friction-dissipative device to verify the effectiveness of the device and the different parameters affecting its performance. An experimental campaign is conducted using different friction materials and bolt loads. The results of these tests were the main source for the selection of friction material for the friction dissipative device of HSTCB. The tests on the HSTCB to RC column connection are performed and discussed in detail.The tested uniaxial friction-dissipative device is suitable for use with bracing for seismic retrofitting of existing structures. Thus, additional research work has been done regarding the retrofitting of RC MRFs using bracings equipped with uniaxial friction dissipative devices. However, in order to keep focus on the main argument of the thesis (HSTCB to RC column dissipative connection) this research work is provided in Appendix A.