Collaborative Research: Development of Innovative, Replaceable Coupling Beam Systems for Damage Mitigation in Coupled Walls

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Coupled walls (CWs) are complex yet attractive lateral force resisting systems that combine extraordinary lateral stiffness with architectural practicality. Despite being an increasingly common system for high rise structures, research on coupled walls is lagging significantly behind that on other structural systems, and the relatively scant body of knowledge for coupled walls cannot adequately address their complex behavior. This research will involve a multi-institutional group of researchers, educators, and practitioners who will synergistically collaborate to build on new and promising innovations for formulating the next generation of earthquake resistant, damage-tolerant coupling beams. The resulting system will balance lateral stiffness, ductility, and superior energy dissipation characteristics; will have replaceable energy dissipating components to reduce the level of damage that is predictable yet repairable with minimal intrusion; will be more architecturally and structurally versatile than current systems; and will exhibit the best overall seismic performance through the use of innovative structural systems designed using performance-based design (PBD) methodologies incorporating sound performance objectives. A closely integrated experimental program and model-based simulations will be used to accomplish these goals. Comprehensive simulations in conjunction with component and substructure testing of sixteen approximately 3/4-scale specimens will generate the fundamental data for development and evaluation of a number of innovative details, and will permit in situ assessment of post-event reparability of coupled walls with innovative coupling beam systems. Hybrid testing of two additional 3/4-scale substructures, using a comprehensive analytical engine, will further examine the performance and post-event reparability of damage-tolerant, replaceable coupling beams subjected to realistic loading histories and boundary conditions. Moreover, hybrid testing will allow an in-depth evaluation of higher mode effects, wall pier-coupling beam interaction, and outrigger action of out-of-plane members as well as other 3-D effectsThe successful project will have immediate and widespread tangible impact on the earthquake engineering community that continues to face major challenges with design of cost effective coupled walls with desirable performance characteristics. The research deliverables will result in more structurally and economically efficient designs and will mitigate post-event damage through the use of innovative energy dissipating coupling beams developed based on PBD methodologies. The multi-faceted dissemination, education, and outreach plan will allow practitioners, researchers, and policy makers to expand and implement the research results for adoption of innovative, damage-tolerant structural systems. The research team has a strong background in design and analysis of coupled walls, development of innovative systems for coupled walls, advanced computational and modeling techniques, testing of complex structural systems, innovative educational and outreach programs, and advancement of state-of-practice through dissemination of research embodied in building codes. Innovative energy dissipating systems combined with PBD concepts will become effective and rational strategies to reduce earthquake impacts on coupled walls. The experimental data, models, simulation tools, methodologies, and systems developed and made available as part of this research will produce new knowledge and advance the state-of-the-art and practice in earthquake engineering, increasing the competitiveness of U.S. firms in the global economy. Additionally, the research deliverables will be broadly applicable to a variety of structural systems, pave the way for additional innovations in damage tolerant structural systems, and serve as a steppingstone for future projects and the development of new concepts for high-rise structures. The research will not only help today's practitioners to more effectively deal with seismic hazard mitigation for a large class of structures but will also educate the next generation of engineers who will work in a rapidly changing technological world where traditional curricula will not be sufficient. This research also impacts training and development of underrepresented groups through outreach activities and involvement of students from inner city high schools.