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Three-segment steel brace for seismic design of concentrically braced frames Onur Sekera, Bulent Akbasb, Pinar Toru Sekera, Mahmoud Faytarounia, Jay Shena,⁎, Mustafa Mahamidc a Department of Civil, Construction and Environmental Engineering, Iowa State University, USA b Department of Earthquake and Structural Engineering, Gebze Institute of Technology, Turkey c Department of Civil and Materials Engineering, University of Illinois at Chicago, USA Keywords: Three-segment steel brace Seismic design Braced frame Non-linear time history analysis Hysteresis A B S T R A C T A three-segment steel brace has been developed and investigated by means of numerical and experimental studies. The objective of the development was to develop a brace member that exhibits stable and symmetrical cyclic response under cyclic loading. The concept was conceived by extending a conventional elastic buckling of a column with variable sections to include post-buckling deformation. The concept was first examined using FEM-based simulations, and tested experimentally with an ensemble of small-scale brace specimens under cyclic loads. Seismic response of CBFs with conventional buckling braces and the three-segment braces were compared and results are discussed in terms of drift, brace and beam ductility demands. The results indicate that the tested three-segment braces specimens were capable of exhibiting stable and symmetrical hysteretic response, as well as dissipating a greater amount of energy compared to conventional buckling braces. Further, the dynamic analyses results point out that substituting the conventional buckling braces with the three-segment braces substantially mitigates the seismic demand on the braced frames. منبع دانلود از پیوست seker2017.pdf

Design and seismic response of modified suspended zipper braced frames Haifeng Yu ⁎, Yaran Guo, Yan Zhang, Xin Wang Hebei University of Science and Technology, Shijiazhuang 050018, China a b s t r a c t In a conventional suspended zipper braced frame (SZBF), the required strength of zipper columns and top story braces increases rapidly with the number of stories, resulting in unacceptable cross sections for these members. To overcome these drawbacks, a new modified suspended zipper braced frame (RZBF) is proposed in this paper. Compared with SZBF, the two central ideas of RZBF are that the unbalanced vertical forces at each story do not reach the maximum values simultaneously, and that the braced beams can transfer part of the unbalanced vertical forces during earthquakes. In order to understand better the seismic performance and design advantages of RZBF, nonlinear time history analyses were conducted on 3, 6, 10, 15, and 18-story RZBF and SZBF models. Comparison of the results obtained demonstrates the efficiency and viability of RZBF. Moreover, it is shown that the RZBF saves more steel material as the number of stories increases. © 2015 Elsevier Ltd. All rights reserved. Keywords: Braced frame Seismic design Zipper column Nonlinear time history analysis Seismic performance 10.1016_j.jcsr.2015.12.025-Design-and-seismic-response-of-modified-suspended-zipper-braced-frames.pdf