A high displacement metallic yielding device for passive energy dissipation
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Earthquake protective systems have been developed in recent decades to minimize the damage occurring to civil engineering structures, especially to buildings and bridges during an earthquake. The technology of earthquake protective systems can be further subcategorized into fields of passive, semi active and active energy dissipation systems. The aim of this dissertation is to develop a passive energy dissipation system for earthquake resistant structures. An effort was made to develop a metallic yielding device which could sustain large displacement demands during an earthquake. In the field of metallic energy dissipation, research conducted in the past had most of its concentration in developing devices for buildings where the drifts are relatively small. Metallic yielding devices have been developed in the past using mild steel because of low carbon content and good ductility. This study involved cyclic coupon testing of mild steel which was followed by analytical modeling of the yielding device using the coupon test results. Before predicting the hysteretic behavior of the yielding device, a previous experimental study conducted on inelastic bending behavior of mild steel rods was also validated analytically using the coupon test results. The presentation of this thesis starts with a background information on energy dissipation technology in the field of earthquake engineering followed by a research objective and plan for this study, literature review and theoretical approaches all presented in chapter 1. Chapter 2 includes various sub topics on analytical modeling concluding with analytical results. Chapter 3 presents the design of the damping device and its working along with a small discussion on the parameters governing the shape and the design of the device. This is concluded by a summary on the final design. Chapter 4 presents a brief discussion on the significance of the targeted coupon testing followed in this study, equipment used and a sub chapter 4.4 which explains as to how the material parameters have been defined for the material model used in chapter 2 for analytical modeling. Chapter 5 presents a brief discussion on the results of the effective damping achieved under different constant amplitude displacements and presents a numerical result which addresses the effect of damping for a base isolated structure. Chapter 6 concludes this study with summary and future work.