Periodic Reporting for period 1 - RFFD (Recentering Friction Floor Dissipater for Resilient-based Design of Steel Structures)
Période du rapport: 2021-10-01 au 2023-09-30
The current built environment, especially in southern European countries, is sensitive to natural hazards, such as earthquakes. As stated by the Press Release of the European Parliament, earthquakes that occurred between August 2016 and January 2017 in Italy led to 333 fatalities, with over 30,000 people displaced and in need of financial assistance. The cost of the earthquake was estimated to be approximately €21.9 billion (1% of Italy’s GDP), and Italy received €1.2 billion of EU aid. Since earthquakes will continue to occur, it is necessary to develop more efficient solutions to improve the resilience of European countries in the aftermath of natural disasters.
Within such a context, the goal of the proposed research is to develop a novel steel building system device, named Recentring Friction Floor Dissipater (RFFD), which can minimize damage and earthquake-induced economic losses in enhanced steel concentrically braced frame buildings while also providing recentring. The novel concept behind the RFFD is that inelastic structural displacements are absorbed by the device between the diaphragm and the lateral load resisting system, rather than only relying on this last as traditionally occurs.
To achieve such an ambitious goal, the following research objectives are proposed:
O1. Simulation-based design of RFFD for inertial force control: The RFFD will be developed by leveraging optimally selected materials for friction applications and durability.
O2. Component-level experimental validation and development of macro-model simulation tools: The macro-scale force-deformation response of the proposed device will be characterized through large-scale cyclic testing coupled with ageing testing (including accelerated corrosion).
O3. System-level experimental validation: Large scale hybrid testing of an 8-storey enhanced steel CBF will be conducted for benchmarking the system performance and the associated simulation models.
O4. Collapse simulations of enhanced CBF buildings under uncertainty: Rigorous earthquake-induced time dependent nonlinear collapse simulations of enhanced versus conventional CBF buildings will be conducted by considering the epistemic and aleatory uncertainties due to friction forces and the ground motion hazard, respectively.
O5. Development of graphics-based design tool for enhanced life-cycle performance: A web-based tool will be developed that integrates multiple structural and non-structural response quantities into a graphical format that satisfy different seismic performance objectives based on rigorous earthquake-induced loss assessment.
Within such a context, the goal of the proposed research is to develop a novel steel building system device, named Recentring Friction Floor Dissipater (RFFD), which can minimize damage and earthquake-induced economic losses in enhanced steel concentrically braced frame buildings while also providing recentring. The novel concept behind the RFFD is that inelastic structural displacements are absorbed by the device between the diaphragm and the lateral load resisting system, rather than only relying on this last as traditionally occurs.
To achieve such an ambitious goal, the following research objectives are proposed:
O1. Simulation-based design of RFFD for inertial force control: The RFFD will be developed by leveraging optimally selected materials for friction applications and durability.
O2. Component-level experimental validation and development of macro-model simulation tools: The macro-scale force-deformation response of the proposed device will be characterized through large-scale cyclic testing coupled with ageing testing (including accelerated corrosion).
O3. System-level experimental validation: Large scale hybrid testing of an 8-storey enhanced steel CBF will be conducted for benchmarking the system performance and the associated simulation models.
O4. Collapse simulations of enhanced CBF buildings under uncertainty: Rigorous earthquake-induced time dependent nonlinear collapse simulations of enhanced versus conventional CBF buildings will be conducted by considering the epistemic and aleatory uncertainties due to friction forces and the ground motion hazard, respectively.
O5. Development of graphics-based design tool for enhanced life-cycle performance: A web-based tool will be developed that integrates multiple structural and non-structural response quantities into a graphical format that satisfy different seismic performance objectives based on rigorous earthquake-induced loss assessment.
During the 3 months period at EPFL, the following tasks were carried out:
1) Literature review regarding dissipation friction devices in steel structures
2) Experimental testing to characterise the tensile and compression mechanical properties of the friction pads. Five different materials were tested in tension and compression. Results were summarised in an internal research report that can be provided upon request
3) The design of the experimental setup to test the RFFD at high speed was carried out. It involved the design of the reaction frame structure supporting the actuator and the RFFD. The 3d model of the experimental setup as well as the calculation report is available upon request.
1) Literature review regarding dissipation friction devices in steel structures
2) Experimental testing to characterise the tensile and compression mechanical properties of the friction pads. Five different materials were tested in tension and compression. Results were summarised in an internal research report that can be provided upon request
3) The design of the experimental setup to test the RFFD at high speed was carried out. It involved the design of the reaction frame structure supporting the actuator and the RFFD. The 3d model of the experimental setup as well as the calculation report is available upon request.
Results are currently limited to a preliminary investingation about new materials to be used for the friction pads.