||Seismic Applications of Hollow Structural Sections in Moment Resisting Frames|
a Milek Fellowship project
||University of Michigan|
||2010 - 2014|
Overview and Objectives: In conjunction with an NSF grant, this research will focus on developing innovative connection methods and concepts for HSS members in high seismic structures. Design of connections for these members using existing common configurations and prevalent engineering concepts is very difficult. The fundamental goal of this project is to investigate and develop innovative HSS moment connection configurations that will provide adequate performance under seismic loads. Prevalent engineering concepts and restrictions in the design of steel frames will be evaluated with regard to their applicability to various HSS frame types. New concepts of modification to current concepts will be provided as part of the project.
Work Description: Initially, a detailed study of the behavior of HSS, CFT, and modified HSS members under large deformations will be undertaken to ensure the formation of a plastic hinge under cyclic flexural loading. Connection details for the various HSS-to-HSS, HSS-to-CFT, and CFT-to-CFT moment connections will then be developed with particular attention paid to design parameters with respect to weld/bolt details, continuity plates, configuration, and other capacity and ductility controlling factors. Upon testing the most promising connection configurations, HSS and CFT-based moment connection design guidelines for use in both IMF and SMF systems will be developed.
- Limits for the development of plastic hinges with adequate ductility for square and rectangular CFT members undergoing bending are determined with respect to the width-to-thickness ratio, depth-to-thickness, and span-to-depth ratio of the HSS member and the strength of the concrete fill
- Development of a collection of viable HSS-to-HSS, HSS-to-CFT, and CFT-to-CFT moment connection configurations
- Data from small-scale tests providing limiting parameters for various tube-based moment connection detail
- Detailed design guidelines for HSS and CFT moment connections developed based on full-scale connection tests
Benefit: These results will initiate efforts towards qualifying these moment connections for IMF and SMF systems. Both a detailed finite element model and practitioner friendly macro-model will be developed in order to explore the behavior of the developed moment frame systems and to aid in their future design.
- Eleven cyclic bending tests conducted on HSS members
- Limits for width-thickness and depth-thickness ratios established
- Design of a seismic moment frame using HSS or CFT members completed
(images courtesy of Dr. McCormick)