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Hybrid Steel Frames

The buildings that are designed according to the building codes generally perform well at severe performance objectives (like life safety) under high earthquake hazard levels. However, the building performance at low performance objectives (like immediate occupancy) under low earthquake hazards is uncertain. The motivation of this research is to modify the design and detailing rules to make the traditional systems perform better at multi-level hazards.

This research introduces two new structural steel systems: hybrid Buckling Restrained Braced Frames (BRBF) and hybrid steel Moment Frames (MF). The "hybrid" term for the BRBF system comes from the use of different steel material including carbon steel (A36), high-performance steel (HPS) and low yield point (LYP) steel. The hybridity of the moment frames is related to the sequence in the plastification of the system which is provided by using weaker and stronger girder sections. Alternative moment frame connections incorporating the use of LYP steel plates are also investigated.

The hybrid BRBF approach was evaluated on seventeen regular (standard) frames with different story heights, seismic design categories and building plans. By varying the steel areas and materials in the BRB cores, three hybrid BRBFs were developed for each regular (standard) frame and their behavior was compared against each other through pushover and incremental dynamic analyses. The benefits of the hybridity were presented using different damage measures such as story accelerations, interstory drifts, and residual displacements. Collapse performance evaluation was also provided.

The performance of hybrid moment frames was investigated on a design space including forty-two moment frame archetypes. Two different hybrid combinations were implemented in the designs with different column sections and different strong column-weak beam (SC/WB) ratios. The efficiency of the hybrid moment frame in which only the girder sizes were changed to control the plastification was compared with regular moment frame designs with higher SC/WB ratios. As side studies, the effect of shallow and deep column sections and SC/WB ratios on the moment frame behavior were also investigated.  

In order to provide adequate ductility in the reduced capacity bays with special detailing, alternative hybrid moment frame connections adapting the use of low strength steel were also studied. / PhD

Identiferoai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/50562
Date22 April 2013
CreatorsAtlayan, Ozgur
ContributorsCivil and Environmental Engineering, Charney, Finley A., Eatherton, Matthew R., Chapman, Martin C., Easterling, William Samuel
PublisherVirginia Tech
Source SetsVirginia Tech Theses and Dissertation
Detected LanguageEnglish
TypeDissertation
FormatETD, application/pdf, application/pdf
RightsIn Copyright, http://rightsstatements.org/vocab/InC/1.0/

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