Seismic Steel Design 12/9/2012 Type MD-Brace Connections R0) shear or bending Eccentrically Braced Frames Buckling-Restrained Braced Frames (BRBFs) Type of concentrically braced frame. ”583oeay1o er时2 c Link beam to coum -Min.rotation capa -Detailing oco -Higher loads in top 2 floors System cominesighsifesshigh ductility. Buckling-Restrained Brace Bucking-Restrained Brace 三 by Dr.Carlos E.Ventura,UBC 10Seismic Steel Design 12/9/2012 by Dr. Carlos E. Ventura, UBC 10 9 December 2012 55 Type MD - Brace Connections Design Brace Axial Forces: • Tension = Ry A Fy • Compression 1.2 Cu Rotation: • Allow rotation to develop upon buckling, or • Design for 1.1 Ry Mpb 9 December 2012 56 27. Seismic Design Requirements Ductile Eccentrically Braced Frames ( R = 4.0 ) Energy dissipation through yielding in links: shear or bending 9 December 2012 57 Eccentrically Braced Frames • Higher capacity for stiffener welds • Link beam to column connections: – Min. rotation capacity – Detailing • Columns – Higher loads in top 2 floors – Moments included in design – Splices designed for shear  = L/e p p L Buckling-Restrained Braced Frames (BRBFs) • Type of concentrically braced frame. • Beams, columns and braces arranged to form a vertical truss. Resist lateral earthquake forces by truss action. • Special type of brace members used: Buckling-Restrained Braces (BRBs). BRBS yield both in tension and compression - no buckling !! • Develop ductility through inelastic action (cyclic tension and compression yielding) in BRBs. • System combines high stiffness with high ductility. Buckling-Restrained Brace Buckling￾Restrained Brace: Steel Core + Casing Casing Steel Core Buckling-Restrained Brace Buckling￾Restrained Brace: Steel Core + A Casing A Section A-A Steel Core Debonding material Casing Steel jacket Mortar