Impact characterization of innovative seismically designed connections for robustness application

The objective of this thesis is the investigation, under static and impact loading, of a new beam-to-column connection called “FREEDAM” (an acronym for FREE from DAMage connections), which have been conceived and developed in the homonym RFCS European project. 

Project: FREEDAM-RFSR-CT-2015-00022. The research activity  has been supported by the European Community with the research grant RFSR-CT-2015-00022. The support of the European Commissionwithin RFCS Research & Innovation is gratefully acknowledged

Partners of the project: ULIEGE, UNISA, UNINA, UC, OFLEIZ, FIP Industriale

Supervisors: Prof. Jean-Pierre Jaspart, Dr. Jean-François Demonceau

Abstract

The modern codes and standards are nowadays requesting the design of resilient structures which means that ensuring the safeguard of the human life is not anymore sufficient. Inded, a resilient design includes the conception and the realization of a structure able to sustain accidental or exceptional events with limited and easy-to-repair damages.

The objective of this thesis is the investigation, under static and impact loading, of a new beam-to-column connection called “FREEDAM” (an acronym for FREE from DAMage connections), which have been conceived and developed in the homonym RFCS European project.

This innovative joint solution, designed to replace the dissipative zones in moment resisting frames (MRFs), is exploiting the concept of supplementary energy dissipation  (also known as passive control) integrated into the seismically designed structure using a friction damper. The main peculiarity relies on the mechanism of energy dissipation based on activation of this friction damper, whose high friction resistance is obtained with innovative coating materials and calibrated controlling the bolt dimension and preload. Thereby, these connections can withstand severe and frequent seismic events without suffering of almost any damage, which is cost-effective if compared with traditional connections where large plastic deformation are expected to occur. Moreover, this solution can also be effectively exploited to improve the robustness of steel buildings through the increase of the local joint ductility. The thesis investigates the impact behaviour in order to account for dynamic loading in simplified static analyses through the use of an amplification coefficient called DIF (Dynamic Increase Factor).