Evaluation of Shear Tab Connections as Supplemental Energy Dissipators

Abstract

As structural engineering practice moves from life-safety to functional recovery after a significant seismic event, taking advantage of structural components to enhance the energy dissipation of a structure will be important. Based on current design criteria, lateral loads are resisted only by the lateral force resisting system. The energy generated by seismic events is designed to be dissipated through plastic deformation in specific ductile components to meet life-safety requirements. Shear tab connections designed as part of gravity load system are assumed as pinned and ignored as contributors to the lateral load resisting system. However, previous research shows that the shear tab connections in the gravity load system can carry moment and dissipate energy as rotation occurs at the end of beam. Including the shear tab connections in the model improves the performance of structure in the seismic analysis as supplemental dissipators. Two modifications to the shear tab connections, adding a Bottom Flange Friction Device (BFFD) and increasing the connection depth (wider bolt spacing), were proposed to improve the performance of shear tab connections. Both modifications provide larger moment strength and stiffness of connection and dissipate more energy. This dissertation is divided into three phases (manuscripts). The first phase of the research project is to experimentally evaluate the shear tab connection with different configurations. The second phase of the research project is to evaluate the shear tab connection with different configurations numerically at the component level. A simplified method of modelling the shear tab connection was proposed for use in numerical building models. The third project phase is to investigate the impact of shear tab connections on the seismic response of steel structures. The findings of the work presented in this dissertation are expected to be useful for performance-based design and seismic analysis of steel structures.