System Behavior Factors for Composite and Mixed Structural Systems
Aritra Chatterjee and Cristopher D. Moen
Yibing Xiang and Sanjay Arwade University of Massachusetts, Amherst Amherst, MA
Benjamin W. Schafer Johns Hopkins University Baltimore, MD
Structural design continues to be a component based process, typically check-ing beam, column and connection capacities against design demands. However, end-user safety in the event of natural hazards hinges on system performance. The challenges in casting structural design as a ‘system-based’ process stems from a fundamental lack of understanding how component level properties, namely component ductility and uncertainty, propagate to system behavior — redundancy, overstrength and system ductility.
This National Science Foundation sponsored Grant Opportunities for Academic Liaison with Industry (GOALI) project, coordinated through the Cold-Formed Steel Research Consortium , www.cfsrc.org, seeks to meet this challenge for typical building structural systems: roof, walls, and floors. Build-ings framed from cold-formed steel are targeted for initial application. The industry partner, the American Iron and Steel Institute (AISI), is working directly with the academic re-search team to insure the research has maximum impact on the practical design of cold-formed steel building sub-systems.
So far the focus has been on wood-sheathed cold-formed steel floor sub-systems under in-plane lateral loads (wind or seismic). High-fidelity finite element models have been developed in ABAQUS and shown to replicate real behavior previously seen in mon-otonic experiments. Surrogate models were generated to study system response in a computationally efficient manner, and dedicated experiments were used to determine component response and uncertainty. These were coupled together to generate system-level strength distributions at first yield and ultimate limit states, and it was shown that component load-deformation behavior has a great impact on system over-strength and ductility. The ongoing parallel efforts are focused on generalizing these methods, and building a full-scale experimental setup at Virginia Tech for testing floor diaphragm sub-systems in order to validate the computational models.