Physics-Based, Nonlinear, Multi-scale, Topology Optimization Framework for Designing Additively Manufactured Energy Dissipating Structural Fuses for Steel Building Systems

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The long-term vision of this award is to render steel building systems in the United States to be more robust and resilient in their performance under extreme seismic events in order to reduce damage and loss of life, and thus enable continued national prosperity and welfare following such events. To achieve this vision, the research goal of this project is to create a physics-based, nonlinear, multi-scale, topology optimization (PB-NMSTO) framework for designing optimal energy dissipating structural components, within a building, using advanced additive manufacturing methods. This project will benefit the academic research community and practicing design engineers by providing an integrated PB-NMSTO design framework. The project will train undergraduate and graduate students in adopting and using additive manufacturing technologies for addressing complex civil infrastructure performance during natural hazard events. The project also will provide a springboard to educate future U.S. engineers through outreach activities at predominantly Native American and Hispanic serving middle and high schools and will foster increased participation of underrepresented groups in STEM areas. Data from this project will be made publicly available through the NSF-supported Natural Hazards Engineering Research Infrastructure Data Depot (https://www.designsafe-ci.org/). Dissipation of energy in building systems under extreme seismic events is a critical design concern. Steel building systems are designed such that plastic energy dissipation (PED) occurs in special components, called energy dissipating fuses (EDFs), while the remaining structural system stays elastic. In steel EDFs, energy is dissipated through multi-scale processes related to material plasticity and damage, and the PED capacity of an EDF depends on its topological design. At present, EDF designs are mostly experimental-based, and there is little insight on how/if these designs are optimal. More importantly, as the design space is constrained by manufacturability, this design methodology severely limits the performance levels that can be realized by full utilization of the material PED capacity. To focus the design efforts on functional optimality, multi-scale plastic-damage models, combined with topology optimization and additive manufacturing, will be introduced in the PB-NMSTO framework for the full exploration of the design space. This will be accomplished by: (a) developing a fundamental understanding of the multi-scale physics of PED in structural steel under cyclic loads, and then (b) using this understanding to solve the inverse problem of topology optimization with the goal of optimally controlling the physics of PED in optimized topologies. It is envisaged that the PB-NMSTO framework will provide the next generation state-of-the-art design paradigm for performance-based design optimization of EDFs that can be additively manufactured.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.