Performance based design using force reduction factor and displacement amplification factors for BFS

In performance based design, the hazard levels and relevant acceptable damages are clearly specified. Structural and non-structural performances are controlled by limiting stiffness, strength and members ductility characteristics. Using displacement amplification factors (Cd) and force reduction factors (R) related to hazard levels, this paper present a method for determination of the stiffness and strength demands needed for BFs (Braced Frames) design. It means that two force reduction factors and two displacement amplification factors are introduced for moderate and major earthquake levels (Immediate Occupancy and Life Safety performances) for determination of stiffness and strength demands. These factors depend on ductility factor, force reduction factor due to ductility and overstrength factor. The procedure for determination of R and Cd factors and value of these factors for Io and LS performance level will be presented in this paper. The results indicate that force reduction factors and displacement amplification factors may be easily used in performance based design methodology.