Design for Drift and Lateral Stability

Abstract

This chapter deals with the problems of drift and lateral stability of building structures. Design for drift and lateral stability is an issue that should be addressed in the early stages of design development. In many cases, especially in tall buildings or in cases where torsion is a major contributor to structural response, the drift criteria can become a governing factor in selection of the proper structural system. The lateral displacement or drift of a structural system under wind or earthquake forces, is important from three different perspectives: 1) structural stability; 2) architectural integrity and potential damage to various non-structural components; and 3) human comfort during, and after, the building experiences these motions. In design of building structures, different engineers attribute various meanings to the term “stability”. Here, we consider only those problems related to the effects of deformation on equilibrium of the structure, as stability problems. Furthermore, we will limit the discussion to the stability of the structure as a whole. Local stability problems, such as stability of individual columns or walls, are discussed in Chapters 9,10, and 11 of the handbook. Several practical methods for inclusion of stability effects in structural analysis as well as simplified drift design procedures are presented. These approximate methods can be valuable in evaluation of the potential drift in the early stages of design. Numerical examples are provided to aid in understanding the concepts, and to provide the reader with the “hands-on” experience needed for successful utilization of the material in everyday design practice.