Analysis of high-rise braced frames with outriggers

A graphical method of analysis for the preliminary design of tall building structures comprising braced frames with outrigger trusses subjected to horizontal loading is presented. For this method of analysis it is necessary to determine five stifnesses for the uniform structure: bending and racking shear stiffnesses of the braced frame and outriggers in addition to a stiffness parameter representing the axial lengthening and shortening of the exterior columns. The analysis allows a simple procedure for obtaining the optimum location of the outrigger up the height of the structure and a rapid assessment of the impact of the outrigger on the behaviour of the high-rise structure. It is concluded that all five stiffnesses should be included in the preliminary analysis of a proposed tall building structure as the reductions in horizontal deflections and bending moments of the braced frame are influenced by all stiffness parameter