Framed-Tube Structures for High-Rise Buildings

The framed-tube system is regarded as an economic solution for high-rise buildings. However, in view of the shear lag which occurs as a result of the flexibility of the spandrel beams, it is essential to predict accurately the structural behavior of the system. A simplified yet accurate method is presented for the analysis of framed-tube structures subjected to wind loads. By recognizing the dominant modes of structural action, the three-dimensional system is replaced by an equivalent plane frame by the addition at the corners of fictitious horizontal members with specially prescribed properties. The plane frame can be analyzed by conventional methods, and it enables larger problems to be treated on a given computer. The accuracy of the method is examined by comparing the results with those from tests on a 15-story perspex model, and from an analysis carried out by a standard three-dimensional space frame computer program.