Experimental Investigation of a Combined System in Steel Braced Frames

Document Type : Structural Earthquake Engineering

Authors

IIEES

Abstract

In general, the analysis and design of buildings must satisfy two criteria. First, under frequently occurring low to moderate earthquakes, the structure should have sufficient strength and stiffness to control deflection and to prevent any structural damage. Second, under rare, severe earthquakes, the structure must have sufficient ductility to prevent collapse. In this case, significant damage to the structure and nonstructural elements is acceptable. In this paper, the performance of an innovative, eccentric and knee bracing system called Eccentrically Knee Brace (EKB) is discussed and the behavior is investigated. A combination of eccentrically braced steel frames and knee braced steel frames has been assessed, and the concepts of the design of defined schemes are reviewed. As the structural fuse of the frame, the knee element will yield first during a moderate earthquake. In large earthquakes, both of them contribute in dissipating energy. Two half-scale EKBs were tested using the SAC loading protocol and an innovative loading protocol. The performance evaluation procedure includes laboratory and computer simulations. Cyclic loading tests were conducted to study the behavior of EKB.

Keywords


American Institute of Steel Construction, AISC (2010) Seismic Provisions for Sstructural Steel Buildings. Chicago.
Roeder, C.W. and Popov, E.P. (1978) Eccentrically braced steel frames for earthquakes. ASCE Journal of Structural Division, 104(3), 391-412.
Hjelmstad, K.D. and Popov, E.P. (1983) Cyclic behavior and design of link beams. ASCE Journal of Structural Engineering, 109(10), 2387-2403.
Kasai, K. and Popov, E.P. (1986) General behavior of WF steel shear link beams. ASCE Journal of Structural Engineering, 112(2), 362-382.
Hjelmstad, K.D. and Popov, E.P. (1983) Seismic Behavior of Active Beam Link in Eccentrically Braced Frames. EERC Report No. 83-15, Berkeley: Earthquake Engineering Research Center, University of California.
Popov, E.P. and Engelhardt, M.D. (1988) Seismic eccentrically braced frames. Journal of Constructional Steel Research, 10, 321-354.
Balendra, T., Sam, M.T., Liaw, C.Y., and Lee, S.L. (1991) Preliminary studies into the behavior of knee braced frames subjected to seismic loading. Engineering Structures, 13(1), 67-74.
FEMA 356 (2000) Prestandard and Commentary for the Seismic Rehabilitation of Buildings, prepared by the American Society of Civil Engineers for the Federal Emergency Management Agency, Washington, D.C.
ASTM (2003) Standard Test Methods and definitions for Mechanical Testing of Steel Products. A370-03a. ASTM International.
SAC Joint Venture (1997) SAC. Protocol for Fabrication, Inspection, Testing and Documentation of Beam-Column Connection Test and Other Experimental Specimens. SAC Rep. SAC/BD-97/02, Sacramento, California.