000009673 001__ 9673
000009673 005__ 20141205153142.0
000009673 04107 $$aeng
000009673 046__ $$k2008-10-12
000009673 100__ $$aChao, Shih-Ho
000009673 24500 $$aPerformance-Based Plastic Design of Steel Concentric Braced Frames for Enhanced Confidence Level

000009673 24630 $$n14.$$pProceedings of the 14th World Conference on Earthquake Engineering
000009673 260__ $$b
000009673 506__ $$arestricted
000009673 520__ $$2eng$$aConcentrically braced steel frames (CBFs) are very efficient and commonly used steel structures for resisting seismic loads because they provide complete truss action. Based on research performed during the last twenty years or so, current U.S. seismic codes now include provisions to design ductile concentric braced frames called Special Concentrically Braced Frames (SCBFs). When designed by conventional elastic design methods, these structures can undergo excessive story drifts after buckling and yielding of bracing members. That can lead to early fractures of the bracing members, especially in those made of popular rectangular tube sections. Recent analytical studies have indicated that the confidence level to achieve collapse prevention performance objectives for typical SCBF can be extremely and unacceptably low when compared with special moment frames (SMFs). This paper presents results of a study in which a newly developed performance-based based plastic design (PBPD) methodology was applied to CBF with buckling type braces. Originally the method was developed and successfully applied to moment frames and more recently extended to other steel framing systems as well. The design concept uses pre-selected target drifts and yield mechanisms as performance limit states. The design lateral forces are derived by using an energy balance equation where the energy needed to push the structure up to the target drift is calculated as a fraction of elastic input energy which is obtained from the selected elastic design velocity spectra. Plastic design is then performed to detail the frame members and connections in order to achieve the intended yield mechanism and behavior. Results of extensive inelastic dynamic analyses carried out on example frames designed by the PBPD method showed that the frames met all the desired performance objectives, including the intended yield mechanisms and the story drifts. Reliability-based evaluation in accordance with FEMA 351 indicated that the PBPD frames have confidence levels against global collapse much higher than those of corresponding SCBFs designed by current practice.

000009673 540__ $$aText je chráněný podle autorského zákona č. 121/2000 Sb.
000009673 653__ $$aConcentrically Braced Frames, Performance-Based Design, PBPD, Plastic Design, Target Drift, Yield Mechanism 

000009673 7112_ $$a14th World Conference on Earthquake Engineering$$cBejing (CN)$$d2008-10-12 / 2008-10-17$$gWCEE15
000009673 720__ $$aChao, Shih-Ho$$iBayat, Mohammad Reza$$iGoel, Subhash C.
000009673 8560_ $$ffischerc@itam.cas.cz
000009673 8564_ $$s398399$$uhttps://invenio.itam.cas.cz/record/9673/files/05-01-0033.pdf$$yOriginal version of the author's contribution as presented on CD, Paper ID: 05-01-0033.
000009673 962__ $$r9324
000009673 980__ $$aPAPER