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Project Title Quantification of Seismic Performance Factors for Steel Staggered Truss and Eccentrically Braced Framing Systems
a Milek Fellowship project
Principal Investigator Shih-Ho Chao
Research Institution University of Texas at Arlington
Project Period 2011 - 2014

Overview and Objectives: Staggered truss frame (STF) system is currently identified as an “undefined structural system” per 2001 CBC section 1629.9.2 and subsequent editions (SEAOC, 2006). In order to confidently use STF in seismic areas, both experimental cyclic test data and analytical studies are required to quantify its seismic performance factors (R, Cd, and Ω0). While the experimental data can be obtained from an ongoing NEESR project (NEESR-CR: Steel Truss Systems with Enhanced Seismic Safety and Performance) that will be conducted by the PI, extensive analytical studies need to be carried out through reliable procedure to determine those seismic design parameters. This proposed study will utilize the recently developed FEMA P695 (FEMA, 2009) procedure for the analytical investigation. It is expected that combination of the NEES experimental results and the analytical studies sponsored by the AISC Fellowship will lead to the use of STFs in seismic zones with great confidence.

The second part of the proposed study will focus on the development of an economical design of eccentrically braced frame (EBF) system, through simpler stiffener detailing for short links and optimal design of non-yielding members. The seismic performance of EBFs under MCE level hazard has not been well studied, especially the stability of the overall system after fracture of the links. This is study will address this issue by conducting extensive analytical study

Work Description:

    • Task 1. Preliminary Analysis of Prototype Structures, including redesign of trusses by following the procedure for special truss moment frames
    • Task 2. Three-Dimensional Nonlinear Time-History Analysis
    • Task 3. Finite Element Analysis on the Connection Behavior
    • Task 4. Collapse Resistance Evaluation of EBFs and Optimization of the Design for Their Non-Yielding Members
    • Task 5. Proof-of-Concept Experimental Study to Verify the Proposed Stiffener Configuration


Deliverables:

    • Design recommendations for STFs
    • Articles in peer reviewed journals including AISCs Engineering Journal describing the work of the fellowship
    • Design recommendations for stiffeners in EBFs


Benefit: Steel STF systems are economical, efficient and accommodating of general architectural and structural requirements for multi-story buildings.

Steel STF systems are economical, efficient and accommodating of general architectural and structural requirements for multi-story buildings.

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