The Earthquake Engineering Online Archive

Analysis and design of tube-type tall building structures

DeClercq, Hendrick; Powell, Graham H.

UCB/EERC-76/05, Earthquake Engineering Research Center, University of California, Berkeley, 1976-02, 207 pages (710.1/C572/1976)

Tube-type structures for tall buildings generally consist of large numbers of members connected at an equally large number of joints. This causes the exact analysis of such structures to be expensive and manual sizing of members during design to be tedious. In this report, a method called the "Macroelement Method," is presented for the approximate analysis of three-dimensional tube-type frames consisting of horizontal beams and vertical columns connected at rigid joints. A linear elastic three-dimensional analysis can be performed very economically by this method for buildings of arbitrary plan, including such structures as bundled tube frames. The macroelement method is a variation of the finite element method, in which a single element embraces a rectangular portion of frame consisting of several columns and several beams. Elements are connected at a small number of nodes. Shape functions are assumed over the region of each element to express the displacements of the beam-column joints in terms of the displacements of the nodes. Numerical results are presented to show that an analysis by this method can yield results which are close to those obtained by an exact analysis, using a fraction of the computer time. In the second part of the report a method for automated design and optimization is presented. This method is a combination of the "Optimality Criterion Method," which ensures satisfaction of displacement constraints, and the fully stressed design process. The cost, area and other properties of a member are expressed in terms of its moment of inertia through families of linear functions. This allows complex relationships to be treated. Numerical examples indicate that the proposed method is well suited for obtaining feasible and inexpensive designs. Convergence to the final design essentially occurs in the first three iteration steps, and each step entails only a few calculations beyond those required for a static analysis. When used with the macroelement method, an optimized design can be obtained for less than the cost of a single exact analysis.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-76-05.pdf (11 MB)