The Relative Stiffness of Steel Eccentric Braced Frame with Dual Vertical Links

Document Type : Research Article


Civil Engineering Faculty, K. N. Toosi University of Technology, Tehran, Iran


The most important characteristics of building frames can be abbreviated in stiffness, strength and ductility. Moment frames have ductile behavior and low stiffness; therefore, the main reason in using the lateral bracing systems is their considerable stiffness. Eccentric bracing systems are considered as ductile frames, while satisfying the required stiffness. The lateral stiffness of conventional eccentric configurations have been calculated previously. In this research, the lateral relative stiffness of eccentrically braced frame with dual vertical links (EBF-DVL) is calculated analytically. EBF-DVL has two parallel vertical links which are welded to the floor beam at the top and to one horizontal link at the bottom. In order to provide the required equations for obtaining the stiffness, the slope-deflection equations are used by considering the effects of shear deformations. The results show that EBF-DVL has a high relative stiffness and by adjusting the lengths of vertical and horizontal links, it is possible to achieve the stiffness even more than the stiffness of eccentric bracing with horizontal link between two diagonal braces. Although an increase in either the moment of inertia or shear area of the vertical link leads to an increase in the lateral stiffness of the system, the effective interval for increasing the moment of inertia of the vertical links is to be limited to approximately half of the column moment of inertia and the corresponding value for increasing the shear area is approximately 60% of the shear area of the column.


[1] T., Hisatoku; T., Segawa; H., Mukai; Experimental Study on the Static Behaviour of the Y-typed Bracings, Report No. 12, Takenaka Technichal Institute, 1974.
[2] S. M., Zahrai; A., Moslehi-Tabar; Cyclic Behaviour of Steel Braced Frames Having Shear Panel System, Asian Journal of Civil Engineering (Building and Housing),Vol. 7, No. 1,pp. 13‑26, 2006.
[3] M., Dicleli; A., Mehta; Efficient Energy Dissipating Steel-Braced Frame to Resist Seismic Loads, Journal of Structural Engineering, Vol. 133, No. 7, pp. 969‑981,2007.
[4] S. M., Zahrai; A., Moslehi-Tabar; Analytical Study on Cyclic Behavior of Chevron Braced Frames with Shear Panel System Considering Post-yield Deformation,Canadian Journal of Civil Engineering, Vol. 40, pp.633‑643, 2013.
[5] A., Ghobarah; H., Abou-Elfath; Rehabilitation of a Reinforced Concrete Frame Using Eccentric Steel Bracing, Engineering Structures, Vol. 23, pp. 745‑755,2001.
[6] F. M., Mazzolani; Innovative Metal Systems for Seismic Upgrading of RC Structures, Journal of Constructional Steel Research, Vol. 64, pp. 882‑895, 2008.
[7] S., Sabouri-Ghomi; C., Ventura; M., Kharrazi; Shear Analysis and Design of Ductile Steel Plate Walls, Journal of Structural Engineering, Vol. 131, No. 6, pp. 878‑889,2005.
[8] K. D., Hjelmstad; E. P., Popov; Cyclic Behavior and Design of Link Beams, Journal of Structural Engineering,ASCE, Vol. 109, pp. 2387‑2403, 1983.
[9] K. D., Hjelmstad; E. P., Popov; Characteristics of Eccentrically Braced Frames, Journal of Structural Engineering, ASCE, Vol. 110, No. 2, pp. 340‑353, 1984.
[10] S. M., Zahrai; H. R., Shahab; The investigation of Using Double Shear Panel to Upgrade the Seismic Behavior of Eccentrically Braced Frames, 1st National Conference of Steel and Structure, 2010 (In Persian).
[11] S., Sabouri-Ghomi; B., Saadati; Numerical Modeling of Vertical Links Behavior in Eccentrically Braced Frames wth Dual Vertical Links, 7th National Congress on Civil Engineering, 2013 (In Persian).
[12] S. M., Zahrai; Study of Using Double Shear Panel to Upgrade the Seismic Behavior of Eccentrically Braced Frames, Modares Civil Engineering Journal, Vol. 13,No. 1, pp. 59-73, 2013 (In Persian).
[13] M. A., Shayanfar; A. R., Rezaeian; S., Taherkhani; Introduction and Study of Seismic Behavior of Eccentrically Braced Frames With Double Vertical Link (DV-EBFs), Journal of Structure and Steel, Vol. 4, No. 3,pp. 74-84, 2008 (In Persian).
[14] M. A., Shayanfar; M. A., Barkhordari; A. R., Rezaeian; Experimental Study of Cyclic Behavior of Composite Vertical Shear Link in Eccentrically Braced Frames,Steel and Composite Structures, Vol. 12, No. 1, pp.13‑29, 2011.